Effect of ovarian stimulation with recombinant follicle-stimulating hormone, gonadotropin releasing hormone antagonists, and human chorionic gonadotropin on endometrial maturation on the day of oocyte pick-up

The prevalence of late-follicular phase progesterone elevation and impact on the ongoing pregnancy rate after fresh and frozen blastocyst transfer. Sub-study of an RCT

The effect of late-follicular phase progesterone elevation (LFPE) during ovarian stimulation on reproductive outcomes in ART treatment remains controversial, but recent studies indicate lower pregnancy rates with rising progesterone levels. This study aims to investigate the prevalence of late-follicular phase progesterone elevation (LFPE) and possible impact on ongoing pregnancy rate after fresh or frozen blastocyst transfer in a sub-study setting of a randomised controlled trial. A total of 288 women were included (n=137 and n=151 in the fresh transfer and freeze-all group, respectively). Among these 11(3.8%) had a progesterone level ≥1.5 ng/ml, and 20(6.9%) had a progesterone level ≥1.2 ng/ml on trigger day. Spline regression analysis showed no significant effect of late follicular phase progesterone levels on ongoing pregnancy. In the multivariate regression analysis (n = 312) only age, but not progesterone level on trigger day was significantly associated with ongoing pregnancy. In conclusion, in a clinical setting with moderate gonadotrophin stimulation and well-defined trigger and fresh transfer cancellation criteria, the prevalence of women with LFPE ≥1.5 ng/ml was low and did not indicate the clinical value of routine measurement of progesterone in the late follicular phase.

Fatty acid supplementation during warming improves pregnancy outcomes after frozen blastocyst transfers: a propensity score-matched study

This study aimed to examine the viability of human blastocysts after warming with fatty acids (FAs) using an in vitro outgrowth model and to assess pregnancy outcomes after a single vitrified-warmed blastocyst transfer (SVBT). For the experimental study, we used 446 discarded vitrified human blastocysts donated for research purposes by consenting couples. The blastocysts were warmed using FA-supplemented (FA group) or non-FA-supplemented (control group) solutions. The outgrowth area was significantly larger in the FA group (P = 0.0428), despite comparable blastocyst adhesion rates between the groups. Furthermore, the incidence of outgrowth degeneration was significantly lower in the FA group than in the control group (P = 0.0158). For the clinical study, we retrospectively analyzed the treatment records of women who underwent SVBT in natural cycles between January and August 2022. Multiple covariates that affected the outcomes were used for propensity score matching as follows: 1342 patients in the FA group were matched to 2316 patients in the control group. Pregnancy outcomes were compared between the groups. The rates of implantation, clinical pregnancy, and ongoing pregnancy significantly increased in the FA group after SVBTs (P = 0.0091-0.0266). These results indicate that warming solutions supplemented with FAs improve blastocyst outgrowth and pregnancy outcomes after SVBTs.

Fertility care for all: impact of New York State's Medicaid expansion on infertility care

PURPOSE

To assess whether the New York State (NYS) mandate expanding Medicaid coverage of fertility diagnostic testing and treatment is successfully increasing patient access to and utilization of fertility care.

METHODS

A retrospective chart review was performed of NYS Medicaid patients who presented for fertility services to a large academic reproductive endocrinology and infertility (REI) clinic. Information on patient demographics, medical history, diagnostic testing, treatments, and outcomes was collected. Patients presenting to the clinic in the 1 year prior to the mandate (October 1, 2018-September 30, 2019) were compared to patients presenting in the 1 year after the mandate (October 1, 2019-September 30, 2020). Primary outcomes of the study were differences in presentation to the clinic between the two cohorts and differences in utilization of infertility diagnostic testing and treatment. Secondary outcomes were differences in treatment outcomes.

RESULTS

A significantly larger percentage of Medicaid patients presented to the clinic for fertility assessment post-mandate (22%) as compared to pre-mandate (9%, p < 0.05). There were no demographic differences between the pre- and post-mandate patient groups. A similar percentage of patients completed diagnostic testing pre- vs. post-mandate. Post-mandate patients underwent more treatment cycles with ovulation induction medications compared to natural treatment cycles. There was no significant difference in pregnancy rates pre- vs. post-mandate.

CONCLUSION

The NYS Medicaid mandate allowed a significantly larger percentage of Medicaid patients to present for fertility evaluation. The patients in the post-mandate cohort underwent more treatment cycles with ovulation induction medications compared to natural cycles.

Individualised gonadotropin dose selection using markers of ovarian reserve for women undergoing in vitro fertilisation plus intracytoplasmic sperm injection (IVF/ICSI)

BACKGROUND

During a stimulated cycle of in vitro fertilisation or intracytoplasmic sperm injection (IVF/ICSI), women receive daily doses of gonadotropin follicle-stimulating hormone (FSH) to induce multifollicular development in the ovaries. A normal response to stimulation (e.g. retrieval of 5 to 15 oocytes) is considered desirable. Generally, the number of eggs retrieved is associated with the dose of FSH. Both hyper-response and poor response are associated with an increased chance of cycle cancellation. In hyper-response, this is due to increased risk of ovarian hyperstimulation syndrome (OHSS), while poor response cycles are cancelled because the quantity and quality of oocytes is expected to be low. Clinicians often individualise the FSH dose using patient characteristics predictive of ovarian response. Traditionally, this meant women's age, but increasingly, clinicians use various ovarian reserve tests (ORTs). These include basal FSH (bFSH), antral follicle count (AFC), and anti-Müllerian hormone (AMH). It is unclear whether individualising FSH dose improves clinical outcomes. This review updates the 2018 version.

OBJECTIVES

To assess the effects of individualised gonadotropin dose selection using markers of ovarian reserve in women undergoing IVF/ICSI.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, and two trial registers in February 2023.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared (a) different doses of FSH in women with a defined ORT profile (i.e. predicted low, normal, or high responders based on AMH, AFC, and/or bFSH) or (b) an individualised dosing strategy (based on at least one ORT measure) versus uniform dosing or a different individualised dosing algorithm.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures. Primary outcomes were live birth/ongoing pregnancy and severe OHSS.

MAIN RESULTS

We included 26 studies, involving 8520 women (6 new studies added to 20 studies included in the previous version). We treated RCTs with multiple comparisons as separate trials for the purpose of this review. Meta-analysis was limited due to clinical heterogeneity. Evidence certainty ranged from very low to low, with the main limitations being imprecision and risk of bias associated with lack of blinding. Direct dose comparisons according to predicted response in women Due to differences in dose comparisons, caution is required when interpreting the RCTs in predicted low responders. All evidence was low or very low certainty. Effect estimates were very imprecise, and increased FSH dosing may or may not have an impact on rates of live birth/ongoing pregnancy, OHSS, and clinical pregnancy. Similarly, in predicted normal responders (10 studies, 4 comparisons), higher doses may or may not impact the probability of live birth/ongoing pregnancy (e.g. 200 versus 100 international units (IU): odds ratio (OR) 0.88, 95% confidence interval (CI) 0.57 to 1.36; I2 = 0%; 2 studies, 522 women) or clinical pregnancy. Results were imprecise, and a small benefit or harm remains possible. There were too few events for the OHSS outcome to enable inferences. In predicted high responders, lower doses may or may not affect live birth/ongoing pregnancy (OR 0.98, 95% CI 0.66 to 1.46; 1 study, 521 women), severe OHSS, and clinical pregnancy. It is also unclear whether lower doses reduce moderate or severe OHSS (Peto OR 2.31, 95% CI 0.80 to 6.67; 1 study, 521 participants). ORT-algorithm studies Eight trials compared an ORT-based algorithm to a non-ORT control group. It is unclear whether live birth/ongoing pregnancy and clinical pregnancy are increased using an ORT-based algorithm (live birth/ongoing pregnancy: OR 1.12, 95% CI 0.98 to 1.29; I2 = 30%; 7 studies, 4400 women; clinical pregnancy: OR 1.04, 95% CI 0.91 to 1.18; I2 = 18%; 7 studies, 4400 women; low-certainty evidence). However, ORT algorithms may reduce moderate or severe OHSS (Peto OR 0.60, 95% CI 0.42 to 0.84; I2 = 0%; 7 studies, 4400 women; low-certainty evidence). There was insufficient evidence to determine whether the groups differed in rates of severe OHSS (Peto OR 0.74, 95% CI 0.42 to 1.28; I2 = 0%; 5 studies, 2724 women; low-certainty evidence). Our findings suggest that if the chance of live birth with a standard starting dose is 25%, the chance with ORT-based dosing would be between 25% and 31%. If the chance of moderate or severe OHSS with a standard starting dose is 5%, the chance with ORT-based dosing would be between 2% and 5%. These results should be treated cautiously due to heterogeneity in the algorithms: some algorithms appear to be more effective than others.

AUTHORS' CONCLUSIONS

We did not find that tailoring the FSH dose in any particular ORT population (low, normal, high ORT) affected live birth/ongoing pregnancy rates, but we could not rule out differences, due to sample size limitations. Low-certainty evidence suggests that it is unclear if ORT-based individualisation leads to an increase in live birth/ongoing pregnancy rates compared to a policy of giving all women 150 IU. The confidence interval is consistent with an increase of up to around six percentage points with ORT-based dosing (e.g. from 25% to 31%) or a very small decrease (< 1%). A difference of this magnitude could be important to many women. It is unclear if this is driven by improved outcomes in a particular subgroup. Further, ORT algorithms reduced the incidence of OHSS compared to standard dosing of 150 IU. However, the size of the effect is also unclear. The included studies were heterogeneous in design, which limited the interpretation of pooled estimates. It is likely that different ORT algorithms differ in their effectiveness. Current evidence does not provide a clear justification for adjusting the dose of 150 IU in poor or normal responders, especially as increased dose is associated with greater total FSH dose and cost. It is unclear whether a decreased dose in predicted high responders reduces OHSS, although this would appear to be the most likely explanation for the results.

Psychosocial wellbeing shortly after allocation to a freeze-all strategy compared with a fresh transfer strategy in women and men: a sub-study of a randomized controlled trial

STUDY QUESTION

Is the psychosocial wellbeing affected in women and men shortly after allocation to a freeze-all strategy with postponement of embryo transfer compared to a fresh transfer strategy?

SUMMARY ANSWER

In general, psychosocial wellbeing (i.e. emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit) was similar in women and men allocated to a freeze-all versus those allocated to a fresh-transfer strategy 6 days after disclosure of treatment strategy (i.e. 4 days after oocyte retrieval), although women in the freeze-all group reported a slightly higher degree of depressive symptoms and mood swings compared to women in the fresh transfer group.

WHAT IS KNOWN ALREADY

The use of a freeze-all strategy, i.e. freezing of the entire embryo cohort followed by elective frozen embryo transfer in subsequent cycles has increased steadily over the past decade in assisted reproductive technology (ART). This strategy essentially eliminates the risk of ovarian hyperstimulation syndrome and has proven beneficial regarding some reproductive outcomes in subgroups of women. However, patients experience a longer time interval between oocyte retrieval and embryo transfer, hence a longer time to pregnancy, possibly adding additional stress to the ART treatment. So far, little focus has been on the possible psychosocial strains caused by postponement of embryo transfer.

STUDY DESIGN, SIZE, DURATION

This is a self-reported questionnaire based sub-study of a multicentre randomized controlled trial (RCT) including 460 women and 396 male partners initiating their first, second, or third treatment cycle of invitro fertilisation or intracytoplasmic sperm injection (ICSI) from May 2016 to September 2018. This sub-study was included in the primary project protocol and project plan for the RCT, as psychosocial wellbeing was considered a secondary outcome.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women from eight public fertility clinics in Denmark and Sweden and one private clinic in Spain were randomized in a 1:1 ratio on the day of inclusion (menstrual cycle day 2 or 3) to either a freeze-all strategy with postponement of embryo transfer to a subsequent modified natural menstrual cycle or a fresh transfer strategy with embryo transfer in the hormone stimulated cycle. Treatment allocation was blinded until the day of the ovulation trigger. Women and their male partners were asked to complete a validated self-reported questionnaire 6 days after unblinding of treatment group allocation, corresponding to 4 days after oocyte retrieval, investigating their psychosocial wellbeing related to the treatment defined as emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit. The questionnaire included items from the Copenhagen Multi-Centre Psychosocial Infertility (COMPI) Fertility Problem Stress Scales and the COMPI Marital Benefit Measure.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline characteristics were comparable between the two groups for both women and men. In total, response rates were 90.7% for women and 90.2% for men. In the freeze-all group, 207 women and 179 men completed the questionnaire compared with 204 women and 178 men in the fresh transfer group. Men in the two treatment groups did not differ in any of the explored aspects of psychosocial wellbeing (i.e. emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit) 6 days after disclosure of treatment strategy. Women in the freeze-all group reported a slightly higher degree of depressive symptoms (P = 0.045) and mood swings (P = 0.001) (i.e. variables included in 'emotional reactions to treatment') compared to women in the fresh transfer group. When adjusted for multiple testing, depressive symptoms were no longer significantly different between the two groups. No additional differences in psychosocial wellbeing were found. Self-reported quality-of-life during treatment was also rated as similar between the two groups in both women and men, but was slightly lower than they would rate their quality-of-life when not in fertility treatment.

LIMITATIONS, REASONS FOR CAUTION

Although response rates were high, selection bias cannot be excluded. As this study was an RCT, we assume that psychosocial characteristics of the participants were equally distributed in the two groups, thus it is unlikely that the identified psychosocial differences between the freeze-all and fresh transfer group were present already at baseline. Furthermore, the questionnaire was completed as a one-time assessment 4 days after oocyte retrieval, thus not reflecting the whole treatment process, whereas an assessment after the full completed treatment cycle is needed to draw firm conclusions about the psychosocial consequences of the whole waiting period. However, a question posted that late would be highly biased on whether or not a pregnancy had been achieved.

WIDER IMPLICATIONS OF THE FINDINGS

The results indicate that individuals in the freeze-all group exhibited slightly higher levels of depressive symptoms and mood swings compared to those in the fresh transfer group. Nevertheless, it is important to note that any worries related to potential emotional strains stemming from delaying embryo transfer should not overshadow the adoption of a freeze-all approach in cases where it is clinically recommended. As long as patients are provided with comprehensive information about the treatment strategy before initiating the process, it is worth emphasising that other aspects of psychosocial wellbeing were comparable between the two groups.

STUDY FUNDING/COMPETING INTEREST(S)

The study is part of the Reprounion collaborative study, co-financed by the European Union, Interreg V Öresund-Kattegat-Skagerrak. L.P. reports financial support from Merck A/S. H.S.N. reports grants from Freya Biosciences ApS, Ferring Pharmaceuticals, BioInnovation Institute, Ministry of Education, Novo Nordic Foundation, Augustinus Fonden, Oda og Hans Svenningsens Fond, Demant Fonden, Ole Kirks Fond and Independent Research Fund Denmark and personal fees from Ferring Pharmaceuticals, Merck A/S, Astra Zeneca, Cook Medical, IBSA Nordic and Gedeon Richter. H.S.N is founder and chairman of the Maternity Foundation and co-developed the Safe Delivery App (non-profit). N.C.F. reports grants from Gedeon Richter, Merck A/S, Cryos International and financial support from Ferring Pharmaceuticals, Merck A/S and Gedeon Richter. N.C.F. is chairman in the steering committee for the guideline groups for The Danish Fertility Society (non-profit). P.H. reports honoraria from Merch A/S, IBSA Nordic and Gedeon Richter. A.L.M.E. reports grants and financial support from Merck A/S and Gedeon Richter. A.P. reports grants from Gedeon Richter, Ferring Pharmaceuticals, Merck A/S and personal fees from Preglem S.A., Novo Nordic Foundation, Ferring Pharmaceuticals, Gedeon Richter, Cryos International, Merch A/S, Theramex and Organon and the lend of embryoscope to the institution from Gedeon Richter. All other authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT02746562.

Effects of reduced follicle-stimulating hormone dosage before human chorionic gonadotropin trigger on in vitro fertilization outcomes

OBJECTIVE

To determine whether a reduced dose of follicle-stimulating hormone (FSH) before human chorionic gonadotropin (hCG) trigger during ovarian stimulation can affect in vitro fertilization (IVF) outcomes.

METHODS

This study included 347 patients with a normal ovarian response who received a reduced dose of FSH before hCG trigger for 2-3 days (Group A) and 671 patients who did not receive a reduced dose (Group B) from a university-affiliated IVF center between January 2021 and December 2022. The primary endpoint was estrogen (E2) and progesterone (P) levels on the day of hCG trigger, fresh embryo transfer cycles, laboratory outcomes, and clinical outcomes between the two groups.

RESULTS

On the day of hCG trigger, Group A had significantly lower E2 and P levels than those in Group B (3454.95 ± 1708.14 pg/mL versus 3798.70 ± 1774.26 pg/mL, p = 0.003; and 1.23 ± 0.53 ng/mL versus 1.37 ± 0.59 ng/mL, p < 0.001, respectively). The proportion of patients with P levels ≥ 1.5 ng/mL was 22.48% in Group A compared to 34.58% in Group B (p < 0.001), while the proportion of patients with E2 ≥ 5000 pg/mL was 15.27% in Group A compared to 25.93% in Group B (p < 0.001). The fresh embryo-transfer cycle rate in Group A was higher than that in group B (54.47% and 32.64%, respectively; p < 0.001). Despite the reduction in FSH dosage, there were no significant differences between groups regarding the number of oocytes retrieved, total number of mature oocytes, normal fertilization rate, cleavage rate, Day 3 top-quality rate, implantation rate, pregnancy rate per cycle, and early pregnancy loss rate.

CONCLUSION

While a reduced dose of FSH prior to hCG trigger during ovarian stimulation did not significantly affect IVF outcomes, it was associated with lower E2 and P levels, resulting in fewer cycles with E2 ≥ 5000 pg/mL and P ≥ 1.5 ng/mL on the day of the hCG trigger.

Elevated estradiol levels on hCG trigger day adversely effects on the clinical pregnancy rates of blastocyst embryo transfer but not cleavage-stage embryo transfer in fresh cycles: a retrospective cohort study

Background

Elevated estradiol (E₂) levels are an inevitable outcome of the controlled ovulation hyperstimulation. However, the effect of this change on pregnancy is still uncertain. Our study aimed to analyze the impact of increased serum E₂ at the day of human chorionic gonadotropin (hCG) administration on the clinical outcomes of women with fresh embryo transfer (ET) cycles.

Methods

This study included 3,009 fresh ET cycles from October 2015 to September 2021. Based on the stage of embryos transferred, these cycles were categorized into the cleavage group and blastocyst group. Both groups were then divided into four sets according to E₂ levels when hCG was administered: set 1 (E₂ ≤ 2,000 pg/ml), set 2 (E₂ = 2,001-3,000 pg/ml), set 3 (E₂ = 3,001-4,000 pg/ml), and set 4 (E₂ > 4,000 pg/ml). The primary outcome was the clinical pregnancy rate (CPR). Binary logistics regression analysis was established to explore the association between CPR and E2 levels. Specifically, the threshold effect of serum E2 on CPR was revealed using the two-piecewise linear regression analyses.

Results

The multivariate regression model in the cleavage group showed that patients' CPR in set 4 was 1.59 times higher than those in reference set 1, but the statistical difference was insignificant (P = 0.294). As for the blastocyst group, patients in set 4 had a lower CPR with adjusted ORs of 0.43 (P = 0.039) compared to patients in set 1. The inflection point for the blastocyst group was 39.7 pg/dl according to the results of the two-piecewise linear regression model. When E₂ levels were over the point, the CPR decreased by 17% with every 1 pg/dl increases in serum E₂ (adjusted OR = 0.83, 95% CI [0.72-0.96], P = 0.012).

Conclusions

Elevated E₂ levels (>39.7 pg/dl) on hCG trigger day were associated with decreased CPR in patients with fresh blastocyst ET. However, it had no similar effect on the CPR of patients with fresh cleavage-stage ET.

The effect of peak serum estradiol level during ovarian stimulation on cumulative live birth and obstetric outcomes in freeze-all cycles

Objective

To determine whether the peak serum estradiol (E2) level during ovarian stimulation affects the cumulative live birth rate (CLBR) and obstetric outcomes in freeze-all cycles.

Methods

This retrospective cohort study involved patients who underwent their first cycle of in vitro fertilization followed by a freeze-all strategy and frozen embryo transfer cycles between January 2014 and June 2019 at a tertiary care center. Patients were categorized into four groups according to quartiles of peak serum E2 levels during ovarian stimulation (Q1-Q4). The primary outcome was CLBR. Secondary outcomes included obstetric and neonatal outcomes of singleton and twin pregnancies. Poisson or logistic regression was applied to control for potential confounders for outcome measures, as appropriate. Generalized estimating equations were used to account for multiple cycles from the same patient for the outcome of CLBR.

Results

A total of 11237 patients were included in the analysis. Cumulatively, live births occurred in 8410 women (74.8%). The live birth rate (LBR) and CLBR improved as quartiles of peak E2 levels increased (49.7%, 52.1%, 54.9%, and 56.4% for LBR; 65.1%, 74.3%, 78.4%, and 81.6% for CLBR, from the lowest to the highest quartile of estradiol levels, respectively, P<0.001). Such association remained significant for CLBR after accounting for potential confounders in multivariable regression models, whereas the relationship between LBR and peak E2 levels did not reach statistical significance. In addition, no significant differences were noticed in adverse obstetric and neonatal outcomes (gestational diabetes mellitus, pregnancy-induced hypertension, preeclampsia, placental disorders, preterm birth, low birthweight, and small for gestational age) amongst E2 quartiles for either singleton or twin live births, both before and after adjustment.

Conclusion

In freeze-all cycles, higher peak serum E2 levels during ovarian stimulation were associated with increased CLBR, without increasing the risks of adverse obstetric and neonatal outcomes.

Impact of progesterone concentration on human chorionic gonadotropin trigger day on clinical outcomes with one top-quality cleavage-stage embryo or blastocyst transfer in fresh in vitro fertilization cycles

Objective

To investigate the impact of the progesterone concentration on the human chorionic gonadotropin (hCG) trigger day on clinical outcomes with an antagonist protocol.

Methods

The retrospective cohort study included a total of 1,550 fresh autologous ART cycles with one top-quality embryo transfer. Multivariate regression analysis, curve fitting, and threshold effect analysis were performed.

Results

A significant association was found between the progesterone concentration and clinical pregnancy rate (adjusted OR, 0.77; 95% CI, 0.62-0.97; P = 0.0234), especially in blastocyst transfer (adjusted OR, 0.56; 95% CI, 0.39-0.78; P = 0.0008). The association between the progesterone concentration and the ongoing pregnancy rate was insignificant. The clinical pregnancy rate showed a linear relationship with an increased progesterone concentration in cleavage-stage embryo transfer. In blastocyst transfer, as the progesterone concentration increased, the clinical and ongoing pregnancy rates showed a parabolic reverse-U curve; the curve initially increased before declining at high progesterone concentrations. The clinical pregnancy rate increased with a progesterone concentration up to 0.80 ng/mL rather than tended to be stable. The clinical pregnancy rate significantly decreased when the progesterone concentration was ≥0.80 ng/mL.

Conclusion

The progesterone concentration on the hCG trigger day exhibits a curvilinear relationship with pregnancy outcomes in blastocyst transfer cycles, and the optimal threshold of the progesterone concentration is 0.80 ng/mL.

Efficacy of long-term pituitary down-regulation pretreatment prior to in vitro fertilization in infertile patients with endometriosis: A meta-analysis

Controversial conclusions have been made in previous studies regarding the influence of ultra-long gonadotropin-releasing hormone agonist (GnRH-a) in the reproductive outcomes of women with endometriosis who are undergoing in vitro fertilization/ intracytoplasmic sperm injection embryo transfer (IVF/ICSI-ET). An electronic search was conducted through PubMed, Embase, Cochrane Library, Web of Science, Elsevier ScienceDirect and Medline from inception until 10 September 2022. Only randomized studies were included. After the selection process, seven articles were eventually included in the meta-analysis. The pooling of the results showed the adverse effect of ultra-long protocol in terms of live birth rate (risk ratio (RR) = 0.53, 95% confidence intervals (CI): 0.31-0.9, P=0.02) and fertilization rate (RR = 1.18, 95% CI: 1.02-1.36, P=0.02). There was no statistical significance between the ultra-long protocol and long protocol of the rest outcome Indicators. The findings of this meta-analysis suggest that ultra-long GnRH-a does not appear to improve the results of IVF/ICSI treatment outcomes in patients with endometriosis.

LH level on ovulation trigger day has a different impact on the outcomes of agonist and antagonist regimens during in vitro fertilization

BACKGROUND

To assess the impact of the luteinizing hormone level on ovulation trigger day (LHOTD) on in vitro fertilization (IVF) outcomes in gonadotropin-releasing hormone (GnRH) agonist and antagonist regimens during fresh embryo transfer cycles.

METHODS

A stepwise, progressive multivariate regression model was introduced to assess the effect of the LHOTD on clinical pregnancy and live birth rates. Mantel‒Haenszel stratification analysis was used to examine the association between the LHOTD and clinical outcomes with the antagonist regimen.

RESULTS

The LHOTD had different distributions in the agonist and antagonist regimens. The cycles were assigned into three LHOTD tertile groups. In the agonist regimen, compared with the 1^st tertile (T1), in the 2^nd (T2) and 3^rd (T3) tertiles, the adjusted odds ratios (ORs) (95% confidence intervals [CIs], P value) were 1.187 (1.047-1.345, 0.007) and 1.420 (1.252-1.610, < 0.001) for clinical pregnancy, respectively, and 1.149 (1.009-1.309, 0.036) and 1.476 (1.296-1.681, < 0.001) for live birth. In the antagonist regimen, there was no significant difference in clinical pregnancy and live birth rates among the tertiles. However, in the stratified group of patients aged less than 35 years, the ORs (95% CIs, P value) of T2 and T3 were 1.316 (1.051-1.648, 0.017) and 1.354 (1.077-1.703, 0.009) for clinical pregnancy, respectively, and 1.275 (1.008-1.611, 0.043) and1.269 (0.999-1.611, 0.051) for live birth. Moreover, there was a discrepancy in the results among the subdivided LHOTD T1 groups adopting the antagonist regimen. Compared with that of the < 1.06 mIU/mL subgroup, the ORs (95% CIs, P value) of the > 1.5 mIU/mL subgroup were 1.693 (1.194-2.400, 0.003) for clinical pregnancy and 1.532 (1.057-2.220, 0.024) for live birth after eliminating potential confounders.

CONCLUSIONS

The LHOTD was profoundly suppressed in the agonist regimen, and its level was positively correlated with clinical pregnancy and live birth rates. In contrast, in the flexible antagonist regimen, the LHOTD was significantly higher than that in the agonist regimen and did not correlate with the outcome, except for women in the nonadvanced age group and those with an excessively suppressed LHOTD. Further investigation is required to determine the rationale for these findings.

Premature timing of progesterone luteal phase support initiation did not negatively impact live birth rates in modified natural frozen thawed embryo transfer cycles

Study question

In a modified natural cycle frozen-thawed embryo transfer (mNC-FET), does the premature timing of progesterone luteal phase support (LPS) initiation 24 h following human chorionic gonadotropin (hCG) trigger impact live birth?

Summary answer

Premature LPS initiation did not negatively affect the live birth rate (LBR) in mNC-FET cycles compared with conventional LPS initiation 48 h after hCG triggering.

What is known already

During natural cycle FET, human chorionic gonadotropin is routinely used to mimic endogenous luteinizing hormone (LH) surge to induce ovulation, which allows more flexibility in embryo transfer scheduling, thus relieving the burden of multiple visits by patients and laboratory workloads, which is also known as mNC-FET. Moreover, recent data demonstrates that ovulatory women undergoing natural cycle FETs have a lower risk of maternal and fetal complications due to the essential role of the corpus luteum in implantation, placentation and pregnancy maintenance. While several studies have confirmed the positive effects of LPS in mNC-FETs, the timing of progesterone LPS initiation is still unclear, as compared with fresh cycles where robust research has been conducted. To the best of our knowledge, no clinical studies comparing different beginning days in mNC-FET cycles have been published.

Study design size duration

This retrospective cohort study involved 756 mNC-FET cycles performed at a university-affiliated reproductive center between January 2019 and August 2021. The primary outcome measured was the LBR.

Participants/materials setting methods

Ovulatory women ≤42 years of age who were referred for their autologous mNC-FET cycles were included in the study. According to the timing of progesterone LPS initiation following the hCG trigger, patients were assigned into two categories: premature LPS group (progesterone initiation 24 h after hCG trigger, n = 182) versus conventional LPS group (progesterone initiation 48 h after hCG trigger, n = 574). Multivariate logistic regression analysis was used to control for confounding variables.

Main results and the role of chance

There were no differences in background characteristics between the two study groups, except for the proportion of assisted hatching (53.8% in premature LPS group versus 42.3% in conventional LPS group, p = 0.007). In the premature LPS group, 56 of 182 patients (30.8%) had a live birth, compared to 179 of 574 patients (31.2%) in the conventional LPS group, with no significant difference observed between groups (adjusted odds ratio [aOR] 0.98, 95% confidence interval [CI] 0.67-1.43, p = 0.913). In addition, there was no significant difference between the two groups in other secondary outcomes. A sensitivity analysis for LBR according to the serum LH and progesterone levels on hCG trigger day also confirmed the aforementioned findings.

Limitations reasons for caution

In this study, retrospective analysis was conducted in a single center and was therefore prone to bias. Additionally, we did not anticipate monitoring the patient's follicle rupture and ovulation after hCG triggering. Future prospective clinical trials remain necessary to confirm our results.

Wider implications of the findings

While exogenous progesterone LPS was added 24 h after hCG triggering, embryo-endometrium synchrony would not be adversely affected so long as sufficient time was allowed for endometrial exposure to exogenous progesterone. Our data support promising clinical outcomes following this event. As a result of our findings, clinicians and patients will be able to make better informed decisions.

Study funding/competing interests

No specific funding was available for this study. The authors have no personal conflicting interests to declare.

Trial registration number

N/A.

Fatty acid supplementation into warming solutions improves pregnancy outcomes after single vitrified-warmed cleavage stage embryo transfers

Purpose

This study aimed to examine the embryonic development of human 4-cell stage embryos after warming with fatty acids (FAs) and to assess the pregnancy outcomes after single vitrified-warmed cleavage stage embryo transfers (SVCTs).

Methods

Experimental study: A total of 217 discarded, vitrified human 4-cell stage embryos donated for research by consenting couples were used. The embryos were warmed using the fatty acid (FA)-supplemented solutions (FA group) or nonsupplemented solutions (control group). The developmental rate, morphokinetics, and outgrowth competence were analyzed. Clinical study: The treatment records of women undergoing SVCT in natural cycles between April and September 2022 were retrospectively analyzed (April-June 2022, control group; July-September 2022, FA group).

Results

Experimental study: The rate of morphologically good blastocysts was significantly higher in the FA group than in the control group (p = 0.0302). The morphokinetics during cleavage, morula, and blastocyst stages were comparable between the groups. The outgrowth was significantly increased in the FA group (p = 0.0438). Clinical study: The rates of implantation, clinical pregnancy, and ongoing pregnancy after SVCTs were significantly increased in the FA group (p = 0.0223-0.0281).

Conclusions

Fatty acid-supplemented warming solutions effectively improve embryo development to the blastocyst stage and pregnancy outcomes after SVCTs.

A novel role of follicle-stimulating hormone (FSH) in various regeneration-related functions of endometrial stem cells

Follicle-stimulating hormone (FSH) promotes the production and secretion of estrogen, which in turn stimulates the growth and maturation of ovarian follicles. Therefore, consecutive FSH treatment to induce ovarian hyperstimulation (superovulation) is still considered the most cost-effective option for the majority of assisted reproductive technologies (ARTs). However, a relatively high cancellation rate and subsequent low pregnancy outcomes (approximately 15%) are the most challenging aspects of this FSH-based ART. Currently, the main cause for this low implantation rate of FSH-based ART has not yet been revealed. Therefore, we hypothesized that these high cancellation rates with FSH-based superovulation protocols might be associated with the harmful effects of consecutive FSH treatment. Importantly, several recent studies have revealed that tissue-resident stem cell deficiency can significantly reduce cyclic endometrial regeneration and subsequently decrease the pregnancy outcome. In this context, we investigated whether FSH treatment could directly inhibit endometrial stem cell functions and consequently suppress endometrial regeneration. Consistent with our hypothesis, our results revealed for the first time that FSH could inhibit various regeneration-associated functions of endometrial stem cells, such as self-renewal, migration, and multilineage differentiation capacities, via the PI3K/Akt and ERK1/2 signaling pathways both in vitro and in vivo.

Follicle-stimulating hormone (FSH) is commonly administered to treat female infertility by stimulating the ovaries, but FSH treatment can also inhibit key cellular and physiological processes required for successful pregnancy. In the light of pregnancy outcomes as low as 15 percent after FSH-based assisted reproduction technologies, In-Sun Hong at Gachon University, Incheon, South Korea, and colleagues investigated the effects of FSH. Working with cultured human stem cells from the lining of the uterus, they found that FSH could inhibit multiple cellular regenerative functions that normally maintain this lining. They also identified a specific molecular signaling pathway involved in mediating these inhibitory effects. Studies in mice supported the cell culture results. The findings could help improve infertility treatment strategies by guiding research into methods to alleviate the unwanted effects of FSH.

Current Biomarkers for Endometrial Receptivity

Implantation and the continuation of pregnancy occur through a complicated and sophisticated dialogue, called “cross-talk,” which starts between the embryo and the endometrium in the early stages of oocyte maturation. This dialogue provides synchronization of the journey of the embryo to be implanted with the receptive endometrium. Understanding the activity and function of the hormones and factors involved in this dialogue will provide an understanding of endometrial receptivity, which plays a key role in implantation, and the determination of biomarkers specific for this period. As a result of the development of omics technology, it has become possible to identify biomarkers specific to endometrial receptivity by performing genomic, proteomic, and lipidomic analyses of these hormones and factors. The determination of these biomarkers, their optimization, and making them usable in the clinic will allow increased success in ART.

The Impact of Suppressing Estradiol During Ovarian Stimulation on the Unsupported Luteal Phase: A Randomized Controlled Trial

CONTEXT

Supraphysiological sex steroid levels at the follicular-luteal phase transition are implicated as the primary cause of luteal insufficiency after ovarian stimulation (OS) for in vitro fertilization.

OBJECTIVE

We aimed to determine the impact of suppressing estradiol levels during OS of multiple dominant follicles on the unsupported luteal phase and markers of endometrial maturation.

METHODS

At 2 university hospitals, 25 eligible egg donors were randomized to undergo OS using exogenous gonadotropins with or without adjuvant letrozole 5 mg/day. Final oocyte maturation was triggered with a GnRH agonist. No luteal support was provided. The primary outcome was the duration of the luteal phase. Secondary outcomes were luteal phase hormone profiles and the endometrial transcriptomic signature 5 days after oocyte pick up (OPU + 5).

RESULTS

The median (interquartile range [IQR]) luteal phase duration was 8.0 (6.8-11.5) days compared with 5.0 (5.0-6.8) days in the intervention and control group, respectively (P < 0.001). Estradiol levels were effectively suppressed in the letrozole group with a median of 0.86 (0.23-1.24) nmol/L at OPU compared to 2.82 (1.34-3.44) nmol/L in the control group. Median (IQR) progesterone levels at OPU + 5 were 67.05 (15.67-101.75) nmol/L in the letrozole group vs 2.27 (1.05-10.70) nmol/L in the control group (P < 0.001). In the letrozole group, 75% of participants revealed endometrial transcriptomic signatures interpreted as post-receptive. In the control group, 40% were post-receptive and 50% noninformative.

CONCLUSION

Suppressing estradiol levels in the follicular phase with adjuvant letrozole significantly reduces the disruption of the unsupported luteal phase after OS.

Differences in Ectopic Pregnancy Rates between Fresh and Frozen Embryo Transfer after In Vitro Fertilization: A Large Retrospective Study

Ectopic pregnancy (EP) is increasingly found in women treated with in vitro fertilization and embryo transfer (IVF−ET). With the development of the freeze-all policy in reproductive medicine, it is controversial whether frozen embryo transfer (FET) could reduce the rate of EP. In this single-center, large-sample retrospective study, we analyzed 16,048 human chorionic gonadotrophin (hCG)-positive patients who underwent fresh embryo transfer (ET) or FET cycles between January 2013 and March 2022. Throughout the study, the total EP rate was 2.09% (336/16,048), 2.16% (82/3803) in the ET group, and 2.07% (254/12,245) in the FET group. After adjustment for age, infertility causes, and other confounding factors, logistic regression results showed no statistical difference in EP rates between FET and ET groups (odds ratio (OR) 0.93 (0.71−1.22), p > 0.05). However, among the 3808 patients who underwent fresh ET cycles, the OR for EP was significantly lower in the long agonist protocol group than in the gonadotropin-releasing hormone antagonist (GnRH-ant) protocol group (OR 0.45 (0.22−0.93), p < 0.05). Through a large retrospective study, we demonstrated a slightly lower EP rate in FET cycles than in fresh ET cycles, but there was no significant difference. The long agonist protocol in ET cycles had a significantly lower risk of EP than the GnRH-ant protocol.

Non-Invasive and Mechanism-Based Molecular Assessment of Endometrial Receptivity During the Window of Implantation: Current Concepts and Future Prospective Testing Directions

Suboptimal endometrial receptivity and altered embryo-endometrial crosstalk account for approximately two-thirds of human implantation failures. Current tests of the window of implantation, such as endometrial thickness measurements and the endometrial receptivity assay, do not consistently improve clinical outcomes as measured by live birth rates. Understanding the mechanisms regulating the endometrial receptivity during the window of implantation is a critical step toward developing clinically meaningful tests. In this narrative review, the available literature is evaluated regarding mechanisms that regulate the endometrial receptivity during the window of implantation and the current tests developed. Overall, both animal and human studies point to five possible and interrelated mechanisms regulating the endometrial window of implantation: suitable synchrony between endometrial cells, adequate synchrony between the endometrium and the embryo, standard progesterone signaling and endometrial responses to progesterone, silent genetic variations, and typical morphological characteristics of the endometrial glands. The biological basis of current clinical markers or tests of window of implantation is poor. Future studies to elucidate the mechanisms shaping the window of implantation and to investigate the potential markers based on these mechanisms are required. In addition, molecular testing of the endometrium at single-cell resolution should be an initial step toward developing clinically meaningful tests for the optimal window of implantation. As understanding of the optimal window of implantation continues to evolve, one can envision the future development of non-invasive, mechanism-based testing of the window of implantation.

Towards an Improved Understanding of the Effects of Elevated Progesterone Levels on Human Endometrial Receptivity and Oocyte/Embryo Quality during Assisted Reproductive Technologies

Ovarian stimulation is an indispensable part of IVF and is employed to produce multiple ovarian follicles. In women who undergo ovarian stimulation with gonadotropins, supraphysiological levels of estradiol, as well as a premature rise in progesterone levels, can be seen on the day of hCG administration. These alterations in hormone levels are associated with reduced embryo implantation and pregnancy rates in IVF cycles with a fresh embryo transfer. This article aims to improve the reader’s understanding of the effects of elevated progesterone levels on human endometrial receptivity and oocyte/embryo quality. Based on current clinical data, it appears that the premature rise in progesterone levels exerts minimal or no effects on oocyte/embryo quality, while advancing the histological development of the secretory endometrium and displacing the window of implantation. These clinical findings strongly suggest that reduced implantation and pregnancy rates are the result of a negatively affected endometrium rather than poor oocyte/embryo quality. Understanding the potential negative impact of elevated progesterone levels on the endometrium is crucial to improving implantation rates following a fresh embryo transfer. Clinical studies conducted over the past three decades, many of which have been reviewed here, have greatly advanced our knowledge in this important area.

Maternal and obstetric outcomes are influenced by developmental stage and cryopreservation of transferred embryos after clomiphene citrate-based minimal stimulation IVF

STUDY QUESTION

Is the embryo transfer (ET) method associated with maternal and perinatal outcomes after minimal stimulation IVF using clomiphene citrate (CC)?

SUMMARY ANSWER

The incidence of pregnancy complications and adverse perinatal outcomes was influenced by the developmental stage (cleavage versus blastocyst stages) and cryopreservation (fresh versus vitrified) of the transferred embryos.

WHAT IS KNOWN ALREADY

Pregnancies resulting from IVF are associated with higher risks of adverse perinatal outcomes compared to natural conceptions; therefore, the next focus in reproductive medicine should be to assess whether these increased risks are attributable to IVF. Pregnancy complications and perinatal outcomes should be considered in addition to pregnancy outcomes when selecting the ET method, however, studies that describe the influence of transfer methods on perinatal and maternal outcomes are limited.

STUDY DESIGN, SIZE, DURATION

This study retrospectively analysed a large single-centre cohort. The clinical records of 36 827 women who underwent oocyte retrieval (during a CC-based minimal stimulation cycle) followed by their first ET at the fertility treatment centre between January 2008 and December 2017 were retrospectively analysed. The patients underwent a single fresh cleavage-stage ET (SFCT), single vitrified-warmed cleavage-stage ET (SVCT) or single vitrified-warmed blastocyst transfer (SVBT). This study only included one cycle per patient.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Oocyte retrieval was performed following CC-based minimal ovarian stimulation. The embryos were transferred 2–3 days after retrieval or vitrified at the cleavage or blastocyst stage. The vitrified embryos were then warmed and transferred within the natural cycles. Pregnancy complications and perinatal outcomes were stratified according to the transfer methods used. Multivariate logistic regression analysis was performed to evaluate the effect of ET methods on the prevalence of pregnancy complications and congenital anomalies.

MAIN RESULTS AND THE ROLE OF CHANCE

The rates of clinical pregnancy and delivery were significantly different among the groups. We analysed pregnancy complications in 7502 singleton births (SFCT, 3395 cycles; SVCT, 586 cycles; and SVBT, 3521 cycles). Multivariate logistic regression analysis revealed that the adjusted odds ratio (AOR) for hypertensive disorders in pregnancy was significantly lower in the SVBT group than in the SFCT group [AOR, 0.72; 95% CI, 0.56–0.92]. The AOR for low-lying placenta was lower in the SVBT group than in the SFCT group (AOR, 0.34; 95% CI, 0.19–0.60). The AOR for placenta previa was lower in the SVCT and SVBT groups than in the SFCT group (AOR, 0.21; 95% CI, 0.07–0.58 versus AOR, 0.53; 95% CI, 0.38–0.75, respectively). A total of 7460 follow-up data on neonatal outcomes was analysed. The AOR for preterm delivery was lower in the SVBT group than in the SFCT group (AOR, 0.78; 95% CI, 0.64–0.94). The AOR for low birthweight was significantly lower after SVCT and SVBT than after SFCT (AOR, 0.68; 95% CI, 0.46–0.98 versus AOR, 0.57; 95% CI, 0.48–0.66, respectively). The AOR for small for gestational age was lower in the SVCT and SVBT groups than in the SFCT group (AOR, 0.68; 95% CI, 0.46–0.98 versus AOR, 0.44; 95% CI, 0.36–0.55, respectively). The AOR for large for gestational age babies was higher in the SVBT group than in the SFCT group (AOR, 1.88; 95% CI, 1.62–2.18). The incidence of each congenital anomaly was similar among the groups.

LIMITATIONS, REASONS FOR CAUTION

The study data were collected through self-reported parental questionnaires on maternal and neonatal outcomes. Our findings were not compared with the incidence of pregnancy complications and congenital anomalies in natural pregnancies. Furthermore, this study was retrospective in nature; therefore, further studies are required to ascertain the generalizability of these findings to other clinics with different protocols and/or different patient demographics.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrated reassuring outcomes for SVBT (in terms of a lower incidence of pregnancy complications) compared to SFCT. Our findings provide valuable knowledge that will help improve perinatal and maternal outcomes in CC-based stimulation and inform couples of the possible benefits and risks of each type of ET method.

STUDY FUNDING/COMPETING INTEREST(S)

This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Evolution of serum progesterone levels in the very early luteal phase of stimulated IVF/ICSI cycles post hCG trigger: a proof of concept study

BACKGROUND

Studies have suggested that controlled ovarian hyperstimulation adversely affects endometrial receptivity due to advanced endometrial maturation. This adverse effect is mainly attributed to supraphysiological levels of both estrogen and progesterone identified in stimulated cycles. There is a paucity of published data investigating the very early luteal steroid profile following hCG trigger.

AIM OF THE STUDY

This prospective, observational study was undertaken to determine the increase in serum progesterone levels after human chorionic gonadotrophin (hCG) trigger in stimulated IVF/ICSI cycles.

MATERIALS AND METHODS

This proof-of-concept study included 11 patients requiring ovarian stimulation for IVF/ICSI and who planned to avail of pre-implantation genetic screening with embryo vitrification of their biopsied embryos at blastocyst stage. For each study participant, five additional blood samples were drawn at the following specific times in the stimulation cycle, on the morning (10.00-12.00) of the assigned day to induce final oocyte maturation with hCG trigger, immediately prior to administration of hCG for final oocyte maturation, 1 h, 2 h, and 36 h post hCG trigger. A prediction model, the Gompertz curve, was used to determine serum progesterone levels at intervals between the 2 h post hCG trigger sample and the day of oocyte retrieval.

RESULTS

Statistically significant increases in serum progesterone levels were identified following hCG administration as early as 1 h following trigger (P4 0.57 ng/ml, p < 0.05), 2 h following trigger (P4 0.88 ng/ml, p < 0.001) and on the day of oocyte retrieval (P4 9.68 ng/ml, p < 0.001). According to our prediction model, the Gompertz curve, the projected serum progesterone level at 4 h post trigger would have achieved a level of 1.45 ng/ml, 8 h post trigger of 3.04 ng/ml, and 12 h post trigger of 4.8 ng/ml. The very early and significant increases in serum progesterone following hCG trigger are clearly demonstrated in this study.

CONCLUSION

The endometrium is undoubtedly exposed to rapidly increasing serum progesterone levels post hCG trigger that would not be identified until much later in natural menstrual cycles.

TRIAL REGISTRATION NUMBER

This study is registered with clinicaltrials.gov under the identifier NCT04417569.

Ovarian Stimulation in Assisted Reproductive Technology Cycles for Varied Patient Profiles: An Indian Perspective

Controlled ovarian stimulation has been an integral part of in vitro fertilisation (IVF) treatment cycles. Availability of different gonadotropins for ovarian stimulation and gonadotropin releasing hormone (GnRH) analogues for prevention of premature rise of leutinising hormone during follicular phase offer an opportunity to utilise them for a successful outcome in women with different subsets of ovarian response. Further, use of GnRH agonist as an alternative for human chorionic gonadotropin improves safety of ovarian stimulation in hyper-responders. Mild ovarian stimulation protocols have emerged as an alternative to conventional protocols in the recent years. Individualisation plays an important role in improving safety of IVF in hyper-responders while efforts continue to improve efficacy in poor responders. Some of the follicular and peri-ovulatory phase interventions may be associated with negative impact on the luteal phase and segmentalisation of the treatment with frozen embryo transfer may be an effective strategy in such a clinical scenario. This narrative review looks at the available evidence on various aspects of ovarian stimulation strategies and their consequences. In addition, it provides a concise summary of the evidence that has emerged from India on various aspects of ovarian stimulation.

Optimal individualization of patient-oriented ovarian stimulation in Japanese assisted reproductive technology clinics, a review for unique setting with advanced-age patients

Ovarian stimulation is a key issue in assisted reproductive technology (ART) treatment. ART practice in Japan is unique with various types of ovarian stimulation protocols, which may contribute to lower pregnancy rates compared to other countries. This review aims to clarify optimal individualized ovarian stimulation for improving the pregnancy rate per one oocyte retrieval cycle in Japan. We performed a literature review to describe ovarian stimulation, classification of infertile women depending on ovarian reserve and response, and Japanese ART data and discussed optimal conventional and mild ovarian stimulation protocols in Japan. According to Japanese ART registry data, the live birth rate of 30-35-year-old women was 32%-37% per ET cycle; therefore, four to five embryos are calculatedly needed when aiming a cumulative live birth rate of ≥80%. Mild stimulation aimed at collecting 5-10 oocytes can be alternative choice as an optimal ovarian stimulation protocol in young women. In 40-year-old women, the live birth rate is 18.8%, resulting in eight or more embryos as necessary. Conventional stimulation must be required in women with advanced age. In poor responders, however, mild stimulation may be sufficient for maximumly extracting their ovarian function. In Japan, mild ovarian stimulation can be selected in patients with a good prognosis and poor responders; however, conventional ovarian stimulation is necessary for women in advanced age.

Nomogram incorporating ultrasonic markers of endometrial receptivity to determine the embryo-endometrial synchrony after in vitro fertilization

BACKGROUND

A successful pregnancy using in vitro fertilization and embryo transfer (IVF-ET) requires a receptive endometrium, good-quality embryos, and a synchronized embryo-endometrial dialogue. Although embryo quality and endometrial receptivity (ER) have been fully assessed to exclude substandard conditions, the probability of successful ET is relatively low. Currently, embryo-endometrial synchrony is considered to be a possible explanation, because delayed, advanced, or narrowed window of implantation (WOI) may lead to ET failure.

OBJECTIVE

This study aims to establish a nomogram incorporating a series of ultrasonic ER markers on the day before implantation to assess the embryo-endometrial synchrony, which may contribute to the improvement of clinical pregnancy outcomes.

METHODS

Totally 583 women with 1135 complete IVF cycles were retrospectively analyzed. Among them, 357 women with 698 cycles and 226 women with 437 cycles were assigned to the training and validation cohorts, respectively. Ultrasonic ER markers obtained on the day before implantation were collected for analyses. In the training cohort, the screened correlates of clinical pregnancy failure were utilized to develop a nomogram for determining whether an infertile woman is suitable for the ET next day. This model was validated both in the training and validation cohorts.

RESULTS

Spiral artery (SA) resistance index (RI), vascularisation index (VI), and flow index (FI) were independently associated with the ET failure (all P < 0.05). They were served as the components of the developed nomogram to visualize the likelihood of implantation failure in IVF-ET. This model was validated to present good discrimination and calibration, and obtained clinical net benefits both in the training and validation cohorts.

CONCLUSION

We developed a nomogram that included SA-RI, VI, and FI on the day before implantation. It may assist physicians to identify patients with displaced WOI, thus avoiding meaningless ET prior to implantation.

Age-specific effect of fresh versus frozen embryo transfer on fetal anomalies or intrauterine growth restriction rate

OBJECTIVE

To compare the prevalence of congenital fetal anomalies or intrauterine fetal growth restriction (IUGR) diagnosed prenatally between two in-vitro fertilization (IVF) methods-fresh embryo transfer (ET) and frozen embryo transfer (FET).

MATERIALS AND METHODS

We retrospectively reviewed medical records of patients that had conceived via IVF, and had a fetal anatomical scan performed at Taiji Clinic between 2015 and 2019. The prevalence of fetal anomalies or IUGR between both IVF methods were compared. Prevalence of congenital anomalies or IUGR by maternal age and embryo transfer type were compared by means of Chi-square analysis. Using multivariate logistic regression, we investigated factors that might be associated with higher rates of fetal anomalies or IUGR, such as parity and number of embryos transferred.

RESULTS

A total of 2441 cases were selected (ET: n = 627 and FET: n = 1814). There was non-significant difference in the prevalence of fetal anomalies or IUGR between ET and FET groups (6.4% vs. 5.5%, p = 0.39). However, among women younger than 34 years of age, prevalence of fetal anomalies or IUGR was significantly higher in ET group (4.6% vs. 9.9%, p = 0.03).

CONCLUSIONS

Our findings suggest an age-specific effect of IVF method on the rate of fetal anomalies or IUGR and may provide useful information for physicians and infertile couples to optimize their IVF treatment plans and improve birth outcomes.

The influence of frozen-thawed and fresh embryo transfer on utero-placental (vascular) development: the Rotterdam Periconception cohort

STUDY QUESTION

Does frozen-thawed or fresh embryo transfer (ET) influence utero-placental (vascular) development, when studied using three-dimensional (3D) ultrasound and virtual reality imaging techniques?

SUMMARY ANSWER

In the first trimester, placental developmental parameters, that is, placental volume (PV) and utero-placental vascular volume (uPVV), were comparable between pregnancies resulting from frozen-thawed ET, fresh ET and natural conception; and in the second and the third trimester, uterine artery Doppler indices were lower in pregnancies after frozen-thawed ET compared to pregnancies after fresh ET and natural conception.

WHAT IS KNOWN ALREADY

Pregnancies after frozen-thawed ET are at risk of developing placenta-related pregnancy complications. There is strong evidence that impaired first-trimester spiral artery remodelling is involved in the pathophysiology of these complications. Studies on longitudinal placental development in pregnancies with different modes of conception, that is, after frozen-thawed ET, fresh ET or natural conception, are lacking.

STUDY, DESIGN, SIZE, DURATION

Women with singleton pregnancies were included before 10 weeks of gestation, between January 2017 and July 2018, as a subcohort of the ongoing Rotterdam Periconception cohort. Results were partially validated in 722 women from the total cohort, which was conducted from November 2010 onwards.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 214 women, of whom 32 conceived after frozen-thawed ET, 56 conceived after fresh ET and 126 conceived naturally, were selected. PV and uPVV measurements were obtained at 7, 9 and 11 weeks of gestation by transvaginal 3D (power Doppler) ultrasound. The uterine artery pulsatility index (UtA-PI) and resistance index (UtA-RI) were measured transvaginally at 7, 9, 11 and 13 weeks and abdominally at 22 and 32 weeks of gestation by pulsed wave Doppler ultrasound. In the validation cohort, the PV was measured in 722 women. Associations between mode of conception and placental development were studied using linear mixed models.

MAIN RESULTS AND THE ROLE OF CHANCE

First-trimester parameters of placental development, that is, PV, uPVV, UtA-PI and UtA-RI, were comparable between pregnancies after frozen-thawed and fresh ET and naturally conceived pregnancies. In our validation cohort, comparable results were found for PV. However, the second- and third-trimester UtA-PI and UtA-RI in pregnancies after frozen-thawed ET were significantly lower than in pregnancies after fresh ET (β_UtA-PI −0.158 (95% CI: −0.268, −0.048), P = 0.005; β_UtA-RI −0.052 (95% CI: −0.089, −0.015), P = 0.006). The second- and third-trimester uterine artery indices in pregnancies after fresh ET were comparable to those in pregnancies after natural conception.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study is the lack of power to optimally detect differences in placental development and placenta-related pregnancy outcomes between pregnancies after different modes of conception. Moreover, our population was selected from a tertiary hospital and included a relatively limited number of pregnancies. Therefore, external validity of the results should be confirmed in a larger sample size.

WIDER IMPLICATIONS OF THE FINDINGS

These findings indicate no significant impact of conception mode on early placental development and a beneficial impact for frozen-thawed ET on the second- and third-trimester Doppler indices. This suggests that frozen-thawed ET may not be as detrimental for placental perfusion as previous research has demonstrated. As the number of clinics applying the ‘freeze-all strategy’ increases, future research should focus on establishing the optimal uterine environment, with regards to hormonal preparation, prior to ET to reduce placental-related pregnancy complications after frozen-thawed ET.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by the Erasmus MC Medical Research Advisor Committee’s ‘Health Care Efficiency Research’ program and the department of Obstetrics and Gynaecology of the Erasmus MC, University Medical Center, Rotterdam, The Netherlands. JSEL reports grants and personal fees from Ferring, personal fees from Titus Healthcare, grants and personal fees from Ansh Labs, grants from NIH, grants from Dutch Heart Association and grants from ZonMW outside the submitted work. None of the other authors have a conflict of interest.

TRIAL REGISTRATION NUMBER

Registered at the Dutch Trial Register (NTR6684).

Higher estradiol levels are associated with lower neonatal birthweight after fresh and frozen embryo transfers. A cohort study of 3631 singleton IVF pregnancies

AIM

To assess the birthweight of neonates conceived after fresh and frozen embryo transfers (FET) and, if different, to investigate whether estradiol levels during the late follicular phase were associated with the observed difference.

METHODS

Singleton pregnancies from fresh and FET transfers between January 1990 and December 2013 were compared retrospectively. A total of 2885 singleton pregnancies after fresh embryo transfer and 746 after FET were analyzed. Obstetric and neonatal outcomes were compared between fresh and FET cycles.

RESULTS

The singletons born after FET were found to have a significantly higher birth weight (3313 g), compared to those born after fresh embryo transfer (3143 g); p < .001. The main predictor of this difference was found to be estradiol levels at the end of the follicular phase. The difference in birthweight was inversely correlated to estradiol levels considering all cycles together but also considering fresh and frozen cycles separately.

CONCLUSIONS

Our study demonstrates a link between high estradiol levels and low birth weight of singletons after IVF both in fresh and frozen-thawed embryo transfer cycles. It provides additional support to the involvement of hyperestrogenemia in the process of implantation and on the subsequent fetal development.

Growth in children conceived by ART

STUDY QUESTION

Is the growth pattern of children conceived by ART different compared to naturally conceived children.

SUMMARY ANSWER

Both ART and underlying parental subfertility may contribute to differences in early childhood growth between children conceived with and without the use of ART.

WHAT IS KNOWN ALREADY

Children conceived by ART weigh less and are shorter at the time of delivery. The extent to which differences in growth according to mode of conception persist during childhood, and the role of underlying parental subfertility, remains unclear.

STUDY DESIGN, SIZE, DURATION

We conducted a prospective study population-based study. We studied 81 461 children participating in the Norwegian Mother, Father and Child Cohort Study (MoBa) and 544 113 adolescents screened for military conscription.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Conception by ART as registered in the Medical Birth Registry. We compared maternally reported length/height and weight among children in MoBa from mid-pregnancy to age 7 according to mode of conception using mixed-effects linear regression. Differences in self-reported height and weight at 17 years of age at screening for military conscription were assessed with linear regression.

MAIN RESULTS AND THE ROLE OF CHANCE

At birth, children conceived by ART were shorter (boys −0.3 cm; 95% CI, −0.5 to −0.1), girls −0.4 cm; 95% CI, −0.5 to −0.3) and lighter (boys −113 grams; 95% CI, −201 to −25, girls −107 grams; 95% CI, −197 to −17). After birth, children conceived by ART grew more rapidly, achieving both greater height and weight at age 3. Children conceived by ART had a greater height up to age 7, but did not have a greater height or weight by age 17. Naturally conceived children of parents taking longer time to conceive had growth patterns similar to ART children. Children born after frozen embryo transfer had larger ultrasound measures and were longer and heavier the first 2 years than those born after fresh embryo transfer.

LIMITATIONS, REASONS FOR CAUTIONS

Selection bias could have been introduced due to the modest participation rate in the MoBa cohort. Our reliance on self-reported measures of length/height and weight could have introduced measurement error.

WIDER IMPLICATIONS OF THE FINDINGS

: Our findings provide reassurance that offspring conceived by ART are not different in height, weight or BMI from naturally conceived once they reach adolescence.

STUDY FUNDING/COMPETING INTEREST(S)

Research Council of Norway; Medical Research Council; National Institute of Environmental Health Sciences. The authors have no competing interest.

TRIAL REGISTRATION NUMBER

N/A.

Supraphysiological estradiol levels on the hCG trigger day are associated with SGA for singletons born from fresh embryo transfer

The effects of supraphysiological estradiol (E2) on neonatal outcomes and the significance of specific E2 concentrations remain unclear. The purpose of this study was to investigate whether supraphysiological E2 levels on the human chorionic gonadotropin (hCG) trigger day are associated with small size for gestational age (SGA) in singletons born from fresh embryo transfer (ET) cycles. Patients with singleton pregnancies who delivered after the transfer of fresh embryos, during the period from July 2012 to December 2017, at our center were included. We excluded cycles involving a vanishing twin, maternal age >35 years, basal follicle-stimulating hormone ≥10 mIU/ml, or anti-Müllerian hormone ≤1 ng/ml. We then divided all cycles into five groups by E2 level on trigger day: group A, <2000 pg/ml (reference group); group B, 2000 pg/ml≤E2<2999 pg/ml; group C, 3000 pg/ml≤E2<3999 pg/ml; group D, 4000 pg/ml≤E2<4999 pg/ml; and group E, ≥5000 pg/ml. The prevalence of SGA among singletons from fresh ET was the primary outcome. The SGA rate significantly increased when the E2 level was ≥4000 pg/ml, as observed by comparing groups D (odds ratio [OR]: 1·79, 95% confidence interval [CI]: 1·16-2·76, P = 0·01) and E (OR: 1·68, 95% CI: 1·10-2·56, P = 0·02) with the reference group. Multivariate logistic regression indicated that a serum E2 level of at least 4000 pg/ml on the hCG trigger day was associated with increased SGA and with significant differences for groups D (adjusted OR [AOR]: 1·65, 95% CI: 1·05-2·59, P = 0·03) and E (AOR: 1·60, 95% CI: 1·03-2·53, P = 0·04) relative to the reference group. In conclusion, in fresh ET cycles, the supraphysiological E2 ≥4000 pg/ml on the hCG trigger day increases the risk of SGA.

Progesterone levels on the human chorionic gonadotropin trigger day affect the pregnancy rates for embryos transferred at different stages of development in both general and selected IVF/ICSI populations

Background

Two meta-analyses have shown that pregnancy and birth rates are significantly higher after blastocyst transfer than after cleaved embryo transfer. Other studies have revealed that a serum progesterone level > 1.5 ng/ml on the trigger day is responsible for premature luteinization and is associated with a low pregnancy rate. The objectives of this retrospective study were to determine whether blastocyst transfer gave higher pregnancy rates than cleaved embryo transfer at day 3 in both the general and selected IVF/ICSI populations, and whether the serum progesterone level influenced the pregnancy rate.

Method

We studied IVF/ICSI cycles with GnRH antagonist - FSH/hMG protocols in a general population (n = 1210) and a selected “top cycle” population (n = 677), after blastocyst transfer on day 5 or cleaved embryo transfer on day 3. The selected couples had to meet the following criteria: female age < 35, first or second cycle, and one or two embryos transferred. We recorded predictive factors for pregnancy and calculated the progesterone to oocyte index (POI), the progesterone:estradiol ratio (P:E2 ratio), and the progesterone to follicle (> 14 mm) index (PFI).

Results

In the general population, the clinical pregnancy rate was significantly higher after blastocyst transfer (33.3%) than after cleaved embryo transfer (25.3%; p <  0.01); the same was true for the birth rate (32.1 and 22.8%, respectively, p <  0.01). The differences between blastocyst and embryo transfer groups were not significant in the selected population (respectively 35.7% vs. 35.8% for the clinical pregnancy rate, and 33.9 and 34.9% for the birth rate). The serum progesterone levels on the eve of the trigger day and on the day itself were significantly lower in the pregnant women (p <  0.01). We found a serum progesterone threshold of 0.9 ng/ml, as also reported by other researchers. The POI and the PFI appear to have predictive value for cleaved embryos transfers.

Conclusions

Blastocyst transfers were associated with higher clinical pregnancy and birth rates than cleaved embryo transfers in a general population but not in a selected population. The serum progesterone levels on the eve of the trigger day and on the day itself predicted the likelihood of pregnancy.

The freeze-all strategy versus agonist triggering with low-dose hCG for luteal phase support in IVF/ICSI for high responders: a randomized controlled trial

STUDY QUESTION

Does the freeze-all strategy in high-responders increase pregnancy rates and improve safety outcomes when compared with GnRH agonist triggering followed by low-dose hCG intensified luteal support with a fresh embryo transfer?

SUMMARY ANSWER

Pregnancy rates after either fresh embryo transfer with intensified luteal phase support using low-dose hCG or the freeze-all strategy did not vary significantly; however, moderate-to-severe ovarian hyperstimulation syndrome (OHSS) occurred more frequently in the women who attempted a fresh embryo transfer.

WHAT IS KNOWN ALREADY

Two strategies following GnRH agonist triggering (the freeze-all approach and a fresh embryo transfer attempt using a low-dose of hCG for intensified luteal phase support) are safer alternatives when compared with conventional hCG triggering with similar pregnancy outcomes. However, these two strategies have never been compared head-to-head in an unrestricted predicted hyper-responder population.

STUDY DESIGN, SIZE, DURATION

This study included women with an excessive response to ovarian stimulation (≥18 follicles measuring ≥11 mm) undergoing IVF/ICSI in a GnRH antagonist suppressed cycle between 2014 and 2017. Our primary outcome was clinical pregnancy at 7 weeks after the first embryo transfer. Secondary outcomes included live birth and the development of moderate-to-severe OHSS.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Following GnRH agonist triggering, women were randomized either to cryopreserve all good-quality embryos followed by a frozen embryo transfer in an subsequent artificial cycle or to perform a fresh embryo transfer with intensified luteal phase support (1500 IU hCG on the day of oocyte retrieval, plus oral estradiol 2 mg two times a day, plus 200 mg of micronized vaginal progesterone three times a day).

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 212 patients (106 in each arm) were recruited in the study, with three patients (one in the fresh embryo transfer group and two in the freeze-all group) later withdrawing their consent to participate in the study. One patient in the freeze-all group became pregnant naturally (clinical pregnancy diagnosed 38 days after randomization) prior to the first frozen embryo transfer. The study arms did not vary significantly in terms of the number of oocytes retrieved and embryos produced/transferred. The intention to treat clinical pregnancy and live birth rates (with the latter excluding four cases lost to follow-up: one in the fresh transfer and three in the freeze-all arms, respectively) after the first embryo transfer did not vary significantly among the fresh embryo transfer and freeze-all study arms: 51/105 (48.6%) versus 57/104 (54.8%) and 41/104 (39.4%) versus 42/101 (41.6%), respectively (relative risk for clinical pregnancy 1.13, 95% CI 0.87-1.47; P = 0.41). However, moderate-to-severe OHSS occurred solely in the group that received low-dose hCG (9/105, 8.6%, 95% CI 3.2% to 13.9% vs 0/104, 95% CI 0 to 3.7, P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

The sample size calculation was based on a 19% absolute difference in terms of clinical pregnancy rates, therefore smaller differences, as observed in the trial, cannot be reliably excluded as non-significant.

WIDER IMPLICATIONS OF THE FINDINGS

This study offers the first comparative analysis of two common strategies applied to women performing IVF/ICSI with a high risk to develop OHSS. While pregnancy rates did not vary significantly, a fresh embryo transfer with intensified luteal phase support may still not avoid the risk of moderate-to-severe OHSS and serious consideration should be made before recommending it as a routine first-line treatment. Future trials may allow us to confirm these findings.

STUDY FUNDING/COMPETING INTEREST(S)

The authors have no conflicts of interest to disclose. No external funding was obtained for this study.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier NCT02148393.

TRIAL REGISTRATION DATE

28 May 2014.

DATE OF FIRST PATIENT’S ENROLMENT

30 May 2014.

Pregnancy outcomes following different protocols of controlled ovarian hyperstimulation in couples undergoing intrauterine insemination

Clomiphene citrate (CC), letrozole and cetrorelix acetate are frequently used agents in controlled ovarian hyperstimulation (COH). However, these three agents have not yet been compared to one another regarding their pregnancy outcomes. The present study was designed to retrospectively compare pregnancy outcomes among the three aforementioned agents. This study involved infertile couples with an infertility duration of at least 2 years, ages 18 to 42 years and who were referred to have their first intrauterine insemination (IUI) treatment cycle. All patients underwent COH with recombinant follicle-stimulating hormone (rFSH) plus CC (n = 118), letrozole (n = 81), or cetrorelix acetate (n = 62), followed by IUI. Using the one-way multivariate analysis of covariance to control female patients' ages, patients stimulated with cetrorelix acetate/rFSH or CC/rFSH had higher numbers of preovulatory follicles than women stimulated with letrozole/rFSH (P < .02), whereas women stimulated with cetrorelix acetate/rFSH had a thicker endometrium than women stimulated with CC/rFSH (P < .0005). Biochemical pregnancy rates were similar among the three protocols of COH. However, women stimulated with letrozole/rFSH showed clinical pregnancy rates higher than those stimulated with CC/rFSH (P = .003) or cetrorelix acetate/rFSH (P = .03) and subclinical abortion rates lower than those stimulated with CC/rFSH or cetrorelix acetate/rFSH (P = .009). Of the different protocols of COH, the odds of having a clinical pregnancy was 3.1 times greater for women stimulated with letrozole/rFSH than women stimulated with CC/rFSH (P = .004) and 2.8 times greater for women stimulated with letrozole/rFSH than women stimulated with cetrorelix acetate/rFSH (P = .03). Our observations show that increased numbers of preovulatory follicles or endometrium thickness do not necessarily improve pregnancy outcomes, because pregnancy outcomes are also subjected to the type of COH used agent. In this regard, letrozole produced fewer preovulatory follicles and did not significantly increase endometrium thickness, but significantly improved pregnancy outcomes in comparison to CC and cetrorelix acetate.

Is frozen embryo transfer better than fresh embryo transfer in women undergoing intracytoplasmic sperm injection over the age of thirty-five? A single referral centre experience

Developments in embryo freezing techniques in recent years have increased the chance of pregnancy after frozen embryo transfers. In this study we aimed to compare the pregnancy outcomes between fresh (ET) and frozen-thawed embryo transfer (FET) and to evaluate the benefits of embryo freezing strategy for a woman of advanced age. A total of 513 ET cycles in women over the age of 35 years, including 397 fresh ET cycles and 116 FET cycles were reviewed. Mean age was 37.7 ± 2.91 years in FET cycles and 38 ± 2.8 in fresh cycles (p = .327). The patients undergoing FET cycles had higher oestradiol levels and progesterone levels on the day of trigger in their previous fresh cycles compared to that of fresh ET cycles (1675 pmol/L versus 991 pmol/L; 1.43 pmol/L versus 0.96 pmol/L; p < .005, respectively). Biochemical pregnancy rates (43% versus 32%; p = .048), clinical pregnancy rates (38% versus 29%; p = .030) and live birth rates (30% versus 19.6%; p = .013) were significantly higher in the FET than in the fresh ET over 35 years of age.IMPACT STATEMENTWhat is alreday known on this subject? Ovarian stimulation commonly results in the generation of more embryos than are necessary for the fresh embryo transfer. Therefore, cryopreservation and subsequent replacement of frozen-thawed embryos is an integral part of assisted reproductive technique (ART) programs. As IVF technology improved, embryo freezing was performed to allow subsequent transfer if the fresh cycle was unsuccessful.What do the results of this study add? Clinical pregnancy rates and live birth rates were found to be higher in frozen thawed embryo transfer group compared to fresh embryo transfer group over the age of 35.What are the implications of these findings for clinical practice and/or further research? Frozen thawed embryo transfer seems to be a reasonable and favourable method compared to fresh embryo transfer in patients over 35 years.

Fetal fraction of cell-free DNA in pregnancies after fresh or frozen embryo transfer following assisted reproductive technologies

STUDY QUESTION

Is the fetal fraction (FF) of circulating cell-free DNA (cfDNA) affected in pregnancies following ART treatment with either fresh or frozen embryo transfer (ET) compared with natural conception?

SUMMARY ANSWER

This study shows a significant reduction in the FF in ART patients compared with naturally conceived pregnancies, which seems to be more pronounced after fresh ET compared with frozen ET.

WHAT IS KNOWN ALREADY

Non-invasive prenatal testing (NIPT) is based on cfDNA in maternal blood, of which about 10% is of placental origin and thus represents the fetal karyotype. Validation studies have demonstrated a high sensitivity, specificity and positive predictive value of NIPT for the detection of fetal trisomy 21, 18 and 13. Nevertheless, the FF of cfDNA is an important factor for NIPT test accuracy. Several studies have found a reduction in FF for pregnancies following ART in comparison with natural conception. However, knowledge on how the FF is affected in ART pregnancies after fresh ET compared with frozen ET is very limited.

STUDY DESIGN, SIZE, DURATION

The study was designed as a case-control study. A total of 54 women with an ongoing pregnancy following ART treatment were included. After exclusion for different reasons, statistical analyses were based on 23 NIPT samples from pregnant women treated with fresh ET and 26 NIPT samples from pregnant women treated with frozen-thawed ET in a modified natural cycle. Women were included between February 2018 and November 2018. The results were compared with a control group of 238 naturally conceived pregnancies with a high-risk result from the combined first trimester screening (cFTS).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included women from the Fertility Clinics at Copenhagen University Hospital Hvidovre and Copenhagen University Hospital Rigshospitalet. Blood samples for NIPT analysis were drawn between 11 + 0 and 14 + 2 weeks of gestation and were all analyzed at the NIPT Center at Copenhagen University Hospital Hvidovre. The NIPT-test was performed by massive-parallel whole-genome sequencing. The FF was determined using the SeqFF algorithm.

MAIN RESULTS AND THE ROLE OF CHANCE

We found a reduction in FF in ART patients compared with naturally conceived pregnancies, and the reduction was more pronounced for ART pregnancies after fresh ET (mean FF = 0.049) compared with frozen ET (mean FF = 0.063) (multivariate analysis adjusted for maternal BMI, P = 0.02). Another multivariate analysis, adjusted for BMI and multiples of median (MoM) values for pregnancy-associated plasma protein-A (PAPP-A), demonstrated a significantly reduced FF for ART pregnancies (mean FF = 0.056) compared with naturally conceived pregnancies (mean FF = 0.072) (P < 0.0001). We found that FF was significantly reduced with increasing maternal BMI (P < 0.0001) and with decreasing MoM values of PAPP-A (P = 0.003).

LIMITATIONS, REASONS FOR CAUTION

A limitation of our study design was the relatively small sample size. Another limitation was that the control group was not matched with the ART-treated women. The majority of the women from the control group had a high risk from cFTS, thereby their biochemical markers were diverging. However, the biochemical markers for the ART-treated women with fresh or frozen ET were not divergent within the subgroups.

WIDER IMPLICATIONS OF THE FINDINGS

Concurrent with other studies demonstrating a reduced FF for singleton pregnancies after ART treatment compared with naturally conceived pregnancies, we found a reduction in FF between the two groups. This is one of the first studies to examine FF in ART pregnancies after fresh ET compared with frozen ET, hence the existing knowledge is limited. We find that FF is even more reduced in pregnancies following fresh ET compared with frozen ET, which might possibly reflect the predisposition of being small for gestational age after fresh ET compared with natural cycle frozen ET.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal (the A.P. Møller Foundation for General Purposes). All authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

NA.

Association between peak serum estradiol level during controlled ovarian stimulation and neonatal birthweight in freeze-all cycles: a retrospective study of 8501 singleton live births

STUDY QUESTION

Is there an association between peak serum estradiol (E2) level during controlled ovarian stimulation (COS) and neonatal birthweight in freeze-all cycles?

SUMMARY ANSWER

Peak serum E2 level during ovarian stimulation is not associated with neonatal birthweight in freeze-all cycles.

WHAT IS KNOWN ALREADY

Supraphysiologic E2 levels during COS have been demonstrated to generate a suboptimal peri-implantation endometrial environment and thus lead to adverse neonatal outcomes in fresh embryo transfer cycles. Previous experimental studies also suggested a potential influence of superovulation on oocyte epigenetic programming, but whether it translates into altered phenotypes of fetal growth and development remains unclear in clinical practice. By segmenting the process of COS and embryo transfer, the freeze-all policy provides a novel model to investigate the sole impact of ovarian stimulation on oocytes after ruling out the effects of hyperestrogenic milieu on endometrium in fresh cycles.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study of 8501 patients who underwent their first COS cycles with a freeze-all strategy and delivered live-born singletons in subsequent frozen-thawed embryo transfer cycles from January 2007 to December 2016 at a tertiary-care academic medical center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were categorized into six groups according to E2 level on trigger day in regular increments of 1000 pg/mL: <1000, 1000-1999, 2000-2999, 3000-3999, 4000-4999 and ≥5000 pg/mL. Univariable and multivariable linear regression and logistic regression analysis were performed to assess the independent association between peak E2 level and measures of neonatal birthweight including absolute birthweight, Z-score, low birthweight (LBW) and small-for-gestational age (SGA).

MAIN RESULTS AND THE ROLE OF CHANCE

The six groups did not differ significantly in birthweight, Z-score or the incidence of LBW and SGA. Compared with the E2 <1000 pg/mL group, the adjusted mean difference (95% confidence interval [CI]) of stratified higher E2 groups was 17.2 (-31.0-65.5), 12.3 (-35.9-60.5), -4.1 (-51.9-43.7), -0.6 (-48.9-47.8) and -3.6 (-50.0-42.8) g for birthweight, and 0 (-0.11-0.10), 0.02 (-0.08-0.12), 0.04 (-0.06-0.14), -0.01 (-0.11-0.10) and -0.04 (-0.14-0.06) for Z-score, respectively. Regarding the outcomes of LBW and SGA, no increased risks were observed in each E2 category, with the adjusted odds ratio (95% CI) being 1.21 (0.68-2.16), 1.0 (0.58-1.90), 0.90 (0.50-1.63), 0.93 (0.51-1.69) and 1.08 (0.61-1.90) for LBW, and 0.97 (0.58-1.64), 1.06 (0.63-1.77), 0.77 (0.46-1.31), 0.71 (0.41-1.22) and 1.00 (0.60-1.65) for SGA, respectively.

LIMITATIONS, REASONS FOR CAUTION

The study was retrospective in design, and other unknown confounding factors may not be included for adjustment. Furthermore, the generalization of the study finding could be limited to some extent by the majority of double cleavage-stage embryo transfer and difference in birthweight reference percentiles between Chinese and other populations.

WIDER IMPLICATIONS OF THE FINDINGS

Our observations suggest that the hyperestrogenic milieu during COS does not seem to pose adverse effects on neonatal birthweight after frozen-thawed embryo transfer, which provides reassuring information for high ovarian responders in freeze-all cycles concerning their offspring's health.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Key Research and Development Program of China (SQ2018YFC100163) and National Natural Science Foundation of China (81571397, 81771533). The authors declare no conflict of interest.

The early luteal hormonal profile in IVF patients triggered with hCG

STUDY QUESTION

What is the early luteal phase hormonal profile in patients undergoing ovarian stimulation for IVF/ICSI followed by hCG trigger and a freeze-all strategy without luteal phase support?

SUMMARY ANSWER

The peak concentration of progesterone occurred 4 days after oocyte pick-up (OPU + 4), with an average 35% fall from OPU + 4 to OPU + 6, and progesterone levels before and 12 h after hCG administration predicted levels during the early luteal phase.

WHAT IS KNOWN ALREADY

The luteal phase during IVF differs from that during normal cycles, particularly with respect to the serum progesterone level profile. This can cause asynchrony between the embryo and the endometrium, potentially resulting in implantation failure and poor reproductive outcomes.

STUDY DESIGN, SIZE, DURATION

This prospective study included 161 women with normal ovarian reserve receiving GnRH antagonist co-treatment during ovarian stimulation with FSH who were followed up to 6 days after OPU in a single IVF cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women aged 18-42 years undergoing IVF with ovarian stimulation using FSH were included. Ovulation was triggered with recombinant hCG 250 μg. Hormone levels were determined from blood samples taken on the day of trigger, before hCG, at 12, 24 and 36 h after hCG and at 1, 2, 3, 4, 5 and 6 days after OPU. The primary endpoint was early luteal phase serum concentrations of progesterone, LH, estradiol and hCG.

MAIN RESULTS AND THE ROLE OF CHANCE

One outlier with a pre-hCG serum progesterone level of 11.42 ng/mL was excluded, so all analyses included 160 subjects. Progesterone levels began to increase 1 day after OPU, peaked 4 days after OPU (114 ng/mL), then declined from OPU + 5 onwards. Peak progesterone levels were at OPU + 4, OPU + 5 or OPU + 6 in 38.8, 29.4 and 13.8% of patients, respectively. Approximately two-thirds of patients had a fall in serum progesterone from OPU + 4 to OPU + 6. Pre-hCG progesterone levels correlated significantly with those at 24 h after hCG (r2 = 0.28; P < 0.001), which in turn correlated significantly with progesterone at OPU + 4 (r2 = 0.32; P < 0.001). LH peaked (4.4 IU/L) 12 h after hCG trigger, persisting for 24 h but was barely elevated compared with physiological levels. Serum estradiol peaked twice: at 24 h post-trigger and at OPU + 4. Highest hCG levels (130 mIU/mL) occurred at 24 h post-injection. The best correlations between the number of follicles ≥11 mm and serum progesterone level were seen at 24 and 36 h after hCG and OPU + 1.

LIMITATIONS, REASONS FOR CAUTION

The influence of different profiles of serum progesterone on reproductive outcomes could not be determined because a freeze-all strategy was used in all patients. In addition, data were not available to relate serum hormone level findings with endometrial histology or endometrial receptivity analysis to clearly identify the relationship between serum hormones and the window of implantation.

WIDER IMPLICATIONS OF THE FINDINGS

Detailed information about early luteal phase hormone levels could be used to optimize and individualize luteal phase support to improve reproductive outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by My Duc Hospital, Ho Chi Minh City, Vietnam. All authors state that they have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

NCT02798146; NCT03174691.

Prenatal growth trajectories and birth outcomes after frozen-thawed extended culture embryo transfer and fresh embryo transfer: the Rotterdam Periconception Cohort

RESEARCH QUESTION

Are there differences in prenatal growth trajectories and birth outcomes between singleton pregnancies conceived after IVF treatment with frozen-thawed extended culture embryo transfer at day 5, fresh embryo transfer at day 3 or naturally conceived pregnancies?

DESIGN

From a prospective hospital-based cohort, 859 singleton pregnancies were selected, including 133 conceived after IVF with frozen-thawed embryo transfer, 276 after fresh embryo transfer, and 450 naturally conceived pregnancies. Longitudinal 3D ultrasound scans were performed at 7, 9 and 11 weeks of gestation for offline crown-rump length (CRL) and embryonic volume measurements. Second trimester estimated fetal weight was based on growth parameters obtained during the routine fetal anomaly scan at 20 weeks of gestation. Birth outcome data were collected from medical records.

RESULTS

No differences regarding embryonic growth trajectories were observed between frozen-thawed and fresh embryo transfer. Birthweight percentiles after fresh embryo transfer were lower than after frozen-thawed embryo transfer (38.0 versus 48.0; P = 0.046, respectively). The prevalence of non-iatrogenic preterm birth (PTB) was significantly lower in pregnancies resulting from fresh embryo transfer compared with frozen-thawed embryo transfer (4.7% versus 10.9%; P = 0.026, respectively). Compared with naturally conceived pregnancies, birthweight percentiles and percentage of non-iatrogenic PTB were significantly lower in pregnancies after fresh embryo transfer and gestational age at birth was significantly higher.

CONCLUSIONS

This study shows that embryonic growth is comparable between singleton pregnancies conceived after fresh and frozen-thawed embryo transfer. The lower relative birthweight and PTB rate in pregnancies after fresh embryo transfer than after frozen-thawed embryo transfer and naturally conceived pregnancies warrants further investigation.

A qualitative study on couples' attitudes and concerns regarding a freeze all strategy in ART treatment

The freeze all strategy has become a promising alternative to fresh embryo transfer in fertility treatment almost eliminating late ovarian hyperstimulation syndrome (OHSS) in the segmented cycle. There is a lack of in-depth knowledge regarding patients' attitudes towards the freeze all strategy. The aim of this study was to explore the attitudes towards a freeze all strategy compared with fresh embryo transfer in assisted reproductive technology (ART) treatment among couples in a public health care setting. We conducted semi-structured qualitative interviews with ten couples already participants in a randomised controlled trial (RCT) and undergoing ART treatment. The couple's responses showed five themes: (i) Starting treatment provides needed relief; (ii) Treatment must be provided with humanity; (iii) Provision of information instigates positive attitudes towards treatment; (iv) Fresh treatment - 'The normal way'; and (v) Freeze all treatment - 'The new black'. When thorough information about treatment procedures and safety aspects regarding both the freeze all and fresh embryo transfer strategy is given prior to initiation of treatment, couples feel secure and content, regardless of which treatment strategy is finally applied. This qualitative study found that starting treatment could prompt longed-for relief, as professionals would now 'take over' and assist in meeting the couple's family building goals.

Fresh versus frozen embryo transfers in assisted reproduction

BACKGROUND

In vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatments conventionally consist of a fresh embryo transfer, possibly followed by one or more cryopreserved embryo transfers in subsequent cycles. An alternative option is to freeze all suitable embryos and transfer cryopreserved embryos in subsequent cycles only, which is known as the 'freeze all' strategy. This is the first update of the Cochrane Review on this comparison.

OBJECTIVES

To evaluate the effectiveness and safety of the freeze all strategy compared to the conventional IVF/ICSI strategy in women undergoing assisted reproductive technology.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Trials Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, and two registers of ongoing trials from inception until 23 September 2020 for relevant studies, checked references of publications found, and contacted study authors to obtain additional data.

SELECTION CRITERIA

Two review authors (TZ and MZ) independently selected studies for inclusion, assessed risk of bias, and extracted study data. We included randomised controlled trials comparing a 'freeze all' strategy with a conventional IVF/ICSI strategy including a fresh embryo transfer in women undergoing IVF or ICSI treatment.

DATA COLLECTION AND ANALYSIS

The primary outcomes were cumulative live birth rate and ovarian hyperstimulation syndrome (OHSS). Secondary outcomes included effectiveness outcomes (including ongoing pregnancy rate and clinical pregnancy rate), time to pregnancy and obstetric, perinatal and neonatal outcomes.

MAIN RESULTS

We included 15 studies in the systematic review and eight studies with a total of 4712 women in the meta-analysis. The overall evidence was of moderate to low quality. We graded all the outcomes and downgraded due to serious risk of bias, serious imprecision and serious unexplained heterogeneity. Risk of bias was associated with unclear blinding of investigators for preliminary outcomes of the study during the interim analysis, unit of analysis error, and absence of adequate study termination rules. There was an absence of high-quality evidence according to GRADE assessments for our primary outcomes, which is reflected in the cautious language below. There is probably little or no difference in cumulative live birth rate between the 'freeze all' strategy and the conventional IVF/ICSI strategy (odds ratio (OR) 1.08, 95% CI 0.95 to 1.22; I² = 0%; 8 RCTs, 4712 women; moderate-quality evidence). This suggests that for a cumulative live birth rate of 58% following the conventional strategy, the cumulative live birth rate following the 'freeze all' strategy would be between 57% and 63%. Women might develop less OHSS after the 'freeze all' strategy compared to the conventional IVF/ICSI strategy (OR 0.26, 95% CI 0.17 to 0.39; I² = 0%; 6 RCTs, 4478 women; low-quality evidence). These data suggest that for an OHSS rate of 3% following the conventional strategy, the rate following the 'freeze all' strategy would be 1%. There is probably little or no difference between the two strategies in the cumulative ongoing pregnancy rate (OR 0.95, 95% CI 0.75 to 1.19; I² = 31%; 4 RCTs, 1245 women; moderate-quality evidence).  We could not analyse time to pregnancy; by design, time to pregnancy is shorter in the conventional strategy than in the 'freeze all' strategy when the cumulative live birth rate is comparable, as embryo transfer is delayed in a 'freeze all' strategy. We are uncertain whether the two strategies differ in cumulative miscarriage rate because the evidence is very low quality (Peto OR 1.06, 95% CI 0.72 to 1.55; I² = 55%; 2 RCTs, 986 women; very low-quality evidence) and cumulative multiple-pregnancy rate (Peto OR 0.88, 95% CI 0.61 to 1.25; I² = 63%; 2 RCTs, 986 women; very low-quality evidence). The risk of hypertensive disorders of pregnancy (Peto OR 2.15, 95% CI 1.42 to 3.25; I² = 29%; 3 RCTs, 3940 women; low-quality evidence), having a large-for-gestational-age baby (Peto OR 1.96, 95% CI 1.51 to 2.55; I² = 0%; 3 RCTs, 3940 women; low-quality evidence) and a higher birth weight of the children born (mean difference (MD) 127 g, 95% CI 77.1 to 177.8; I² = 0%; 5 RCTs, 1607 singletons; moderate-quality evidence) may be increased following the 'freeze all' strategy. We are uncertain whether the two strategies differ in the risk of having a small-for-gestational-age baby because the evidence is low quality (Peto OR 0.82, 95% CI 0.65 to 1.05; I² = 64%; 3 RCTs, 3940 women; low-quality evidence).

AUTHORS' CONCLUSIONS

We found moderate-quality evidence showing that one strategy is probably not superior to the other in terms of cumulative live birth rate and ongoing pregnancy rate. The risk of OHSS may be decreased in the 'freeze all' strategy. Based on the results of the included studies, we could not analyse time to pregnancy. It is likely to be shorter using a conventional IVF/ICSI strategy with fresh embryo transfer in the case of similar cumulative live birth rate, as embryo transfer is delayed in a 'freeze all' strategy. The risk of maternal hypertensive disorders of pregnancy, of having a large-for-gestational-age baby and a higher birth weight of the children born may be increased following the 'freeze all' strategy. We are uncertain if 'freeze all' strategy reduces the risk of miscarriage, multiple pregnancy rate or having a small-for-gestational-age baby compared to conventional IVF/ICSI.

A Premature Rise of Luteinizing Hormone Is Associated With a Reduced Cumulative Live Birth Rate in Patients ≥37 Years Old Undergoing GnRH Antagonist In Vitro Fertilization Cycles

This is a retrospective cohort study included 1021 patients underwent a flexible GnRH antagonist IVF protocol from January 2017 to December 2017 to explore the effect of a premature rise in luteinizing hormone (LH) level on the cumulative live birth rate. All patients included received the first ovarian stimulation and finished a follow-up for 3 years. A premature rise in LH was defined as an LH level >10 IU/L or >50% rise from baseline during ovarian stimulation. The cumulative live birth rate was calculated as the number of women who achieved a live birth divided by the total number of women who had either delivered a baby or had used up all their embryos received from the first stimulated cycle. In the advanced patients (≥37 years), the cumulative live birth rate was reduced in patients with a premature rise of LH (β: 0.20; 95% CI: 0.05-0.88; p=0.03), compared to patients (≥37 years) without the premature LH rise. The incidence of premature LH rise is associated with decreased rates of cumulative live birth rate in patients of advanced age (≥37 years) and aggravated the reduced potential of embryos produced by the advanced age, not the number of embryos.

Gonadotropin-releasing hormone analogs: Mechanisms of action and clinical applications in female reproduction

Extra-hypothalamic GnRH and extra-pituitary GnRH receptors exist in multiple human reproductive tissues, including the ovary, endometrium and myometrium. Recently, new analogs (agonists and antagonists) and modes of GnRH have been developed for clinical application during controlled ovarian hyperstimulation for assisted reproductive technology (ART). Additionally, the analogs and upstream regulators of GnRH suppress gonadotropin secretion and regulate the functions of the reproductive axis. GnRH signaling is primarily involved in the direct control of female reproduction. The cellular mechanisms and action of the GnRH/GnRH receptor system have been clinically applied for the treatment of reproductive disorders and have widely been introduced in ART. New GnRH analogs, such as long-acting GnRH analogs and oral nonpeptide GnRH antagonists, are being continuously developed for clinical application. The identification of the upstream regulators of GnRH, such as kisspeptin and neurokinin B, provides promising potential to develop these upstream regulator-related analogs to control the hypothalamus-pituitary-ovarian axis.

Effects of waiting time between failed fresh cycle embryo transfer and the next frozen embryo transfer on pregnancy outcomes in assisted reproductive technology

OBJECTIVE

To explore how waiting time after failed fresh cycle embryo transfer affects the pregnancy outcomes of the next frozen embryo transfer (FET).

METHODS

A retrospective analysis was carried out on the data of women who had received at least one FET after a failed fresh embryo transfer between January 2013 to December 2019. The women were grouped based on the "time" of the first FET, referring to the period between a failed fresh embryo transfer and the beginning of the next cycle of FET. This time is divided into two classes: immediate (<90 days after the failed fresh embryo transfer) and delayed (≥90 days after failed fresh embryo transfer). The following parameters were investigated: clinical pregnancy rate; biochemical pregnancy rate; ectopic pregnancy rate; and non-pregnancy rate.

RESULTS

A total of 293 cases of fresh embryo transfer cycles were included. No significant differences in the number of obtained oocytes, total number of FET, and the total amount of gonadotropin were seen between the immediate and delayed fresh embryo transfer groups. The pregnancy outcomes of the two groups were similar.

CONCLUSION

The duration of waiting time between failed fresh embryo transfer and the next FET does not affect pregnancy outcomes.

Risk of gestational diabetes mellitus in women achieving singleton pregnancy spontaneously or after ART: a systematic review and meta-analysis

BACKGROUND

Women who achieve pregnancy by ART show an increased risk of obstetric and perinatal complications compared with those with spontaneous conception (SC).

OBJECTIVE AND RATIONALE

The purpose of this systematic review and meta-analysis was to synthesize the best available evidence regarding the association between ART and gestational diabetes mellitus (GDM) in women with singleton pregnancies. The research question asked was whether the risk of GDM is higher in women achieving singleton pregnancy by ART compared with those achieving singleton pregnancy spontaneously.

SEARCH METHODS

A literature search, in MEDLINE, Scopus and Cochrane databases, covering the period 1978–2019, was performed aiming to identify studies comparing the risk of GDM in singleton pregnancies after ART versus after SC. Both matched and unmatched studies were considered eligible. Meta-analysis of weighted data was performed using the random effects model. Results were reported as risk ratio (RR) with 95% CI. Heterogeneity was quantified with the I² index.

OUTCOMES

The study reports on 63 760 women who achieved a singleton pregnancy after ART (GDM was present in 4776) and 1 870 734 women who achieved a singleton pregnancy spontaneously (GDM in 158 526). Women with singleton pregnancy achieved by ART showed a higher risk of GDM compared with those with singleton pregnancy achieved spontaneously (RR 1.53, 95% CI 1.39–1.69; I² 78.6%, n = 37, 1 893 599 women). The direction or the magnitude of the effect observed did not change in subgroup analysis based on whether the study was matched (n = 17) or unmatched (n = 20) (matched: RR 1.42, 95% CI 1.17–1.72; I² 61.5%—unmatched: RR 1.58, 95% CI 1.40–1.78; I² 84.1%) or whether it was prospective (n = 12) or retrospective (n = 25) (prospective studies: RR 1.52, 95% CI 1.27–1.83, I² 62.2%—retrospective studies: RR 1.53, 95% CI 1.36–1.72, I² 82.5%). Regarding the method of fertilization, a higher risk of GDM after ART versus SC was observed after IVF (n = 7), but not after ICSI (n = 6), (IVF: RR 1.95, 95% CI 1.56–2.44, I² 43.1%—ICSI: RR 1.42, 95% CI 0.94–2.15, I² 73.5%). Moreover, regarding the type of embryo transfer (ET), a higher risk of GDM after ART versus SC was observed after fresh (n = 14) but not after frozen (n = 3) ET (fresh ET: RR 1.38, 95% CI 1.03–1.85, I² 75.4%—frozen ET: RR 0.46, 95% CI 0.10–2.19; I² 73.1%). A higher risk of GDM was observed after ART regardless of whether the eligible studies included patients with polycystic ovary syndrome (RR 1.49, 95% CI 1.33–1.66, I² 75.0%) or not (RR 4.12, 95% CI 2.63–6.45, I² 0%), or whether this information was unclear (RR 1.46, 95% CI 1.22–1.75, I² 77.7%).

WIDER IMPLICATIONS

The present systematic review and meta-analysis, by analysing 1 893 599 women, showed a higher risk of GDM in women achieving singleton pregnancy by ART compared with those achieving singleton pregnancy spontaneously. This finding highlights the importance of early detection of GDM in women treated by ART that could lead to timely and effective interventions, prior to ART as well as during early pregnancy.

Is there an optimal number of oocytes retrieved at which live birth rates or cumulative live birth rates per aspiration are maximized after ART? A systematic review

The association between the number of oocytes retrieved and fresh live birth rate (LBR) or cumulative LBR (CLBR), and whether an optimal number of oocytes are retrieved when LBR or CLBR are maximized, are highly relevant clinical questions; however published results are conflicting. A systematic review of all eligible studies (n = 16) published until January 2020 on MEDLINE, Embase, Scopus, CINAHL and Web of Science was conducted. Five studies evaluated only LBR from fresh cycles, five studies evaluated only CLBR from stimulated cycles and six evaluated both. A marked difference was observed between the oocyte yields at which LBR and CLBR were reportedly maximized in the individual studies. On the basis of nine studies, the optimal number of oocytes at which fresh LBR seems to be maximized is proposed to be between 12 and 18 oocytes (15 oocytes was the most common suggestion). On the other hand, CLBR continues to increase with the number of oocytes retrieved. This is the first systematic review on the topic, and it suggests that the retrieval of 12-18 oocytes is associated with maximal fresh LBR, whereas a continuing positive association is present between the number of oocytes retrieved and CLBR.

Are different markers of endometrial receptivity telling us different things about endometrial function?

PROBLEM

To what extent do endocrine, immunological, gene expression and histological markers of endometrial receptivity correlate?

METHOD OF STUDY

Between November 2017 and September 2019, 121 women referred to a University Hospitals Fertility Clinic consented to inclusion in this cohort study. The women underwent timed endometrial biopsy followed by blood samples in a hormone-substituted cycle. Of these, 37 women had just started IVF treatment, and the remaining 84 had experienced recurrent implantation failure following IVF/ICSI. The hormone-substituted cycle consisted of initiation with oral oestradiol followed by addition of vaginal progesterone treatment for five full days. Endometrial biopsies were subject to histological examination, immune cell markers by immunohistochemistry (CD56⁺ , CD16⁺ , CD163⁺ , FoxP3) and gene expression microarray analyses with the endometrial receptivity array (ERA^® ) test (Igenomix). Plasma progesterone and oestradiol were measured on the day of biopsy.

RESULTS

CD56⁺ uterine natural killer (uNK) cell counts correlate with transcriptional markers of endometrial receptivity assessed by the ERA test. Endometrial maturation, receptivity and immunological markers were not correlated with mid-luteal blood plasma progesterone level. Mid-luteal serum oestradiol level correlated with markers of endometrial maturation and receptivity. The tests were carried out during a standard hormone substitution cycle, and the findings may not apply in the natural cycle.

CONCLUSION

CD56⁺ uNK cell counts and endometrial receptivity assessed by the ERA test appear to be linked. Mid-luteal progesterone levels were not correlated to the tested markers of endometrial receptivity. In contrast, mid-luteal oestradiol level was inversely related to markers of endometrial receptivity and maturation.