Maternal and perinatal outcomes after fresh versus frozen embryo transfer-what is the risk-benefit ratio?

Comparison of Fetal Crown-Rump Length Measurements between Thawed and Fresh Embryo Transfer

Background and Objectives: Neonates born from thawed embryo transfers tend to have a significantly higher birthweight compared to those from fresh embryo transfers. The aim of this study was to compare the crown-rump length (CRL) between thawed and fresh embryos to investigate the potential causes of different growth patterns between them. Materials and Methods: This was a retrospective study (July 2010-December 2023) conducted at the Third Department of Obstetrics and Gynecology, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. In total, 3082 assisted reproductive technology (ART) pregnancies (4044 embryos) underwent a routine scan at 11+0-13+6 gestational weeks and were included in the study. Maternal age, the type of embryo transfer (thawed vs. fresh, donor vs. their own oocytes), CRL, twin and singleton gestations were analyzed. Results: The mean maternal age in thawed was significantly higher than in fresh embryos (39.8 vs. 35.8 years, p-value < 0.001). The mean CRL z-score was significantly higher in thawed compared to fresh embryo transfers (0.309 vs. 0.199, p-value < 0.001). A subgroup analysis on singleton gestations showed that the mean CRL z-score was higher in thawed blastocysts compared to fresh (0.327 vs. 0.215, p-value < 0.001). Accordingly, an analysis on twins revealed that the mean CRL z-score was higher in thawed blastocysts (0.285 vs. 0.184, p-value: 0.015) and in oocytes' recipients compared to own oocytes' cases (0.431 vs. 0.191, p-value: 0.002). Conclusions: The difference in CRL measurements between thawed and fresh embryos may be a first indication of the subsequent difference in sonographically estimated fetal weight and birthweight. This finding highlights the need for additional research into the underlying causes, including maternal factors and the culture media used.

Live birth rate following endometrial preparation with daily versus depot GnRH agonist

BACKGROUND

Gonadotrophin-releasing hormone agonist (GnRHa) downregulates gonadotropin secretion in the pituitary gland. It is used both in ovulation induction protocols and in artificial endometrium preparation. Frozen-thawed embryo transfer to artificially prepared endometrium (FET-APE) is a frequent procedure in vitro fertilization (IVF) which requires GnRHa. It can be used either as a daily low-dose injection or as a single depot injection. It is unclear which of these two regimens is superior for artificial endometrium preparation.

METHODS

We evaluated the data of 72 patients who had undergone frozen embryo transfer following the 5th day Preimplantation Genetic Test-aneuploidy (PGT-A) between 2018-2021. All embryos were genetically screened, and euploid single embryos were transferred. Group 1 (n: 36) used depot GnRHa, and Group 2 (n: 36) used single daily injections for artificial endometrial preparation. The outcomes for Beta Human Chorionic Gonadotrophin (BHCG) positivity and live birth rates (LBR) was compared.

RESULTS

The BHCG positivity for Group 1 and Group 2 was 75% and 80.6%, respectively. The LBR for Group 1 and Group 2 were found to be 58.3% and 63.9%, respectively. There was no statistically significant differences between the two groups.

CONCLUSIONS

In artificial endometrium preparation, depot GnRHa offers cheaper and more convenient alternative to single daily dose injections, particularly in busy clinical settings.

Long-Term Effects of ART on the Health of the Offspring

Assisted reproductive technologies (ART) significantly increase the chance of successful pregnancy and live birth in infertile couples. The different procedures for ART, including in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), intrauterine insemination (IUI), and gamete intrafallopian tube transfer (GIFT), are widely used to overcome infertility-related problems. In spite of its inarguable usefulness, concerns about the health consequences of ART-conceived babies have been raised. There are reports about the association of ART with birth defects and health complications, e.g., malignancies, high blood pressure, generalized vascular functional disorders, asthma and metabolic disorders in later life. It has been suggested that hormonal treatment of the mother, and the artificial environment during the manipulation of gametes and embryos may cause genomic and epigenetic alterations and subsequent complications in the health status of ART-conceived babies. In the current study, we aimed to review the possible long-term consequences of different ART procedures on the subsequent health status of ART-conceived offspring, considering the confounding factors that might account for/contribute to the long-term consequences.

Review of Endometrial Receptivity Array: A Personalized Approach to Embryo Transfer and Its Clinical Applications

Successful outcomes of in vitro fertilization (IVF) rely on both the formation of a chromosomally normal embryo and its implantation in a receptive endometrium. Pre-implantation genetic testing for aneuploidy (PGT-A) has been widely accepted as a tool to assess the viability of an embryo. In 2011, the endometrial receptivity array (ERA) was first published as a tool to determine when the endometrium is most receptive to an embryo, commonly referred to as the "window of implantation" (WOI). The ERA uses molecular arrays to assess proliferation and differentiation in the endometrium and screens for inflammatory markers. Unlike PGT-A, there has been dissent within the field concerning the efficacy of the ERA. Many studies that contest the success of the ERA found that it did not improve pregnancy outcomes in patients with an already-good prognosis. Alternatively, studies that utilized the ERA in patients with repeated implantation failure (RIF) and transfer of known euploid embryos demonstrated improved outcomes. This review aims to describe the ERA as a novel technique, review the various settings that the ERA may be used in, such as natural frozen embryo transfer (nFET) and hormone replacement therapy frozen embryo transfer (HRT-FET), and provide a summary of the recent clinical data for embryo transfers in patients with RIF utilizing the ERA.

Endometrial thickness is an independent risk factor of hypertensive disorders of pregnancy: a retrospective study of 13,458 patients in frozen-thawed embryo transfers

BACKGROUND

Hypertensive disorders of pregnancy (HDP) are an important cause of maternal and fetal mortality, and its potential risk factors are still being explored. Endometrial thickness (EMT), as one of the important monitoring indicators of endometrial receptivity, has been confirmed to be related to the incidence of HDP in fresh embryo transfer. Our study was designed to investigate whether endometrial thickness is associated with the risk of hypertensive disorders of pregnancy in frozen-thawed embryo transfer (FET).

METHODS

This respective cohort study enrolled 13,458 women who received vitrified embryo transfer and had a singleton delivery in the Reproductive Hospital affiliated to Shandong University from January 2015 to December 2019. We set strict screening criteria and obtained the information from the hospital electronic medical system. Statistical methods including logistic regression analysis, receiver operating characteristic curve and restricted cubic spline were used to evaluate the relationship between endometrial thickness and the incidence of pregnancy-induced hypertension.

RESULTS

The incidences of HDP in a thin endometrial thickness group (< 0.8 cm) and a thick endometrial thickness group (> 1.2 cm) were significantly greater than in a reference group (0.8 cm-1.2 cm) (7.98 and 5.24% vs 4.59%, P <  0.001). A nonlinear relationship between endometrial thickness and risk of hypertensive disorders of pregnancy was examined by restricted cubic spline (P <  0.001). The thin endometrial thickness and thick endometrial thickness groups were significantly associated with the risk of HDP after adjusting for confounding variables by stepwise logistic regression analysis. Subsequently, subgroup logistic regression analysis based on endometrial preparation regimens showed that thin endometria were still significantly associated with a higher morbidity rate in the artificial cycle group, while in the natural cycle group, thick endometria were closely associated with increased morbidity.

CONCLUSION

Our study manifested that both the thin and thick endometria were associated with an increased risk of hypertensive disorders of pregnancy in frozen embryo transfer cycles. Reproductive clinicians should focus on adjusting endometrial thickness in different preparation regimens; and obstetricians should be mindful of the risk of hypertension during pregnancy, when women with thin (< 0.8 cm) or excessively thicker (> 1.2 cm) endometrial thickness achieve pregnancy through frozen-thawed embryo transfer.

Influences of fresh and frozen embryo transfer on neonatal birthweight and the expression of imprinted genes PEG10 /L3MBTL1 in placenta

To investigate the influences of fresh embryo transfer (ET) and frozen embryo transfer (FET) on neonatal birthweight and the expression of imprinted genes PEG10 and L3MBTL1 in the placenta after in vitro fertilization-embryo transfer (IVF-ET), we analyzed the neonatal birthweight between fresh ET and FET transfer cycles. Then, we collected placentas delivered by fresh ET and FET, and real-time quantitative PCR, Western blotting and immunohistochemistry were used to detect the expression of PEG10 and L3MBTL1. The mean neonatal birthweight of fresh ET was lower than that of FET(3348.48 ± 521.05 vs. 3450.34 ± 524.13, P < 0.001). The risks of low birthweight (LBW) and small-for-gestational age (SGA) were lower after FET (3.9 % vs. 5.4 %; 7.2 % vs. 10.3 %), with adjusted rate ratios of 0.74 (95 % CI, 0.59-0.93; P = 0.003) and 0.70 (95 % CI, 0.59-0.84; P < 0.001), respectively. FET resulted in higher frequencies of macrosomia and large-for-gestational age (LGA) (14.2 % vs. 10.3; 11.0 % vs. 7.1 %) than fresh ET, with adjusted rate ratios of 1.45 (95 % CI, 1.26-1.68; P < 0.001) and 1.62 (95 % CI, 1.37-1.91; P < 0.001), respectively. We also observed PEG10 mRNA and protein expression levels in placentas delivered by fresh ET and FET were significantly different, but there were no significant differences in L3MBTL1 between the two groups. Fresh ET may affect the expression of the imprinted gene PEG10 in the placenta and adverse to placental implantation and development, resulting to increasing incidences of LBW and SGA.

Association Between Fresh Embryo Transfers and Frozen-Thawed Embryo Transfers Regarding Live Birth Rates Among Women Undergoing Long Gonadotropin-Releasing Hormone Antagonist Protocols

Background: The availability and use of frozen-thawed embryos after controlled ovarian hyperstimulation for assisted reproduction have increased with improvements in vitrification techniques and the rise of gonadotropin-releasing hormone (GnRH) antagonist protocols. Although evidence has shown that frozen-thawed embryo transfers (FETs) result in higher live birth rates than fresh embryo transfers, it is uncertain whether this association exists in cycles employing the GnRH antagonist protocol. Objective: To test the hypothesis that FETs are more likely to result in a live birth than fresh embryo transfers in a GnRH antagonist protocol cycle and to investigate whether frozen blastocyst transfer increases live birth rates compared to fresh blastocyst transfer. Design: A retrospective historical cohort study was conducted using data collected from the Department of Reproductive Medicine of Liuzhou Maternity and Child Healthcare Hospital for 1,437 patients who underwent the GnRH antagonist protocol between 1 January 2015, and 31 December 2020. The primary outcome was the live birth rate, which was compared between fresh embryo transfer and FET, and the secondary outcomes were clinical pregnancy rate and miscarriage rate, which were compared between the two groups. Analyses were adjusted to account for the age of the patient, number of embryo transfers, day of embryo transfer, and type of infertility. Results: Fresh embryo transfers accounted for 1,026 (71.4%) of the 1,437 patients who underwent the GnRH antagonist protocol in our analysis, while FETs accounted for 411 (28.6%). Patients with fresh and frozen-thawed embryos had comparable median body mass index (body mass index; 22.3 [IQR, 24.6-20.0] vs. 22.0 [IQR, 24.5-19.9]). There was a significant difference in the median age of the fresh embryo transfer group (34.0 [IQR, 39.0-30.0]) and the Frozen-thawed embryo transfer group (32.0 [IQR, 37.0-29.0]). Blastocysts were transferred in 14.6% of the fresh embryo transfer cycles and 45.5% of the FET cycles, whereas they account for 10.4% and 13.0% of all patients, respectively. The mean number of embryos transferred was 2 (IQR, 2.0-1.0) for the fresh embryo transfer group and 1 (IQR, 2.0-1.0) for the FET group, with a significant difference in the mean number of embryos transferred. The live birth rate after fresh embryo transfer vs. FET was 28.7% vs. 34.5% (absolute difference, 5.9%; adjusted relative risk [aRR], 1.15 [95% CI, 0.88-1.51]). The clinical pregnancy rates were 39.9% vs. 46.0%, respectively (absolute difference, 6.1%; aRR, 1.10 [95% CI, 0.85-1.43]). The miscarriage rates were 22.5% vs. 23.8%, respectively (absolute difference, 1.3%; aRR, 1.13 [95% CI, 0.75-1.70]). Conclusion: In this retrospective study of women who underwent assisted reproduction using GnRH antagonists, FETs resulted in a higher live birth rates and clinical pregnancy rates than fresh embryo transfers, which parts of these differences were attributable to embryo stage. However, the interpretation of the findings is limited by the possibility of selection and confounding biases.

Preimplantation genetic testing and frozen embryo transfer synergistically decrease very pre-term birth in patients undergoing in vitro fertilization with elective single embryo transfer

PURPOSE

To study the effects of frozen embryo transfer (FET) and FET post-PGT on pre-term and very pre-term births in patients undergoing in vitro fertilization (IVF).

MATERIALS AND METHODS

A study was conducted using the SART National Summary Report from 2014 to 2017. Cycle inclusion criteria were eSET, fresh embryo transfers (ET), frozen embryo transfers without PGT (FET), and frozen embryo transfers with PGT (FET/PGT). Exclusion criteria were use of gestational carriers and donor eggs. Pregnancy outcomes included live births and gestational age at birth.

RESULTS

A total of 161,550 eSETs were analyzed for the effect of FET and FET/PGT on IVF outcome and pre-term births including 43,618 ET, 58,812 FET, and 59,120 FET/PGT cycles. Live birth rates in patients with FET/PGT were significantly higher than those in ET (52.9% vs 46.4%, P < 0.0001) and FET (52.9% vs 43.1%, P < 0.0001). Patients with FET had a significantly lower live birth rate compared with that of ET (43.1% vs 46.4%, P < 0.0001). Both FET and FET/PGT significantly decreased total pre-term births compared with ET (10.8% and 10.5% vs 11.5%, P < 0.05 and < 0.001). FET/PGT significantly reduced very pre-term births when compared with ET and FET (1.5% vs 2.0%, P < 0.0001 and 1.5% vs 1.9%, P = 0.0002).

CONCLUSION

This study demonstrates that PGT significantly improves IVF outcome. Moreover, patients undergoing FET/PGT had significantly decreased total pre-term births. More importantly, patients with FET/PGT had significantly lower very pre-term births.

When Should We Freeze Embryos? Current Data for Fresh and Frozen Embryo Replacement IVF Cycles

Recent years have seen a dramatic rise in the number of frozen-thawed embryo replacement (FER) cycles. Along with the advances in embryo cryopreservation techniques, the optimization of endometrial receptivity has resulted in outcomes for FER that are similar to fresh embryo transfer. However, the question of whether the Freeze all strategy is for all is nowadays a hot topic. This review addresses this issue and describes current evidence based on randomized controlled trials and observational studies. To date, it is reasonable to perform FER in cases with a clear indication for the benefits of such strategy including impending ovarian hyperstimulation syndrome (OHSS) or preimplantation genetic testing for aneuploidy (PGT-A); however, this strategy does not fit for all. This review analyses the pros and cons of the freeze all strategy highlighting the need to follow a personalized plan in embryo transfer, avoiding a freeze all methodology for all patients in an unselected manner.

A systematic review of clinical efficacy of frozen-thawed embryos and fresh embryos in in-vitro fertilization cycles

BACKGROUND

Frozen-thawed embryo (FTE) and fresh embryo (FE) transfer are two common strategies in vitro fertilization (IVF), while the results and findings still vary among studies.

METHODS

We searched multiple databases for relevant studies comparing the clinical effects of FTE and FE. Meta-analyses were conducted with Review Manager 5.0 to assess the efficacy among included articles. We also analyzed the risk of bias for the reports.

RESULTS

Nine studies eventually met the inclusion criteria from 2010 to 2018, and 11396 patients were included. The meta-analyses indicated no significant difference in biochemical pregnancy, clinical pregnancy and ongoing pregnancy rates. Meanwhile, the implantation rate and live birth rate in frozen-thawed embryos were much higher than those of fresh embryo. The birth weight in the frozen-thawed ET group was greater than that of the FE group, and the low birth weight rate in FTE was lower than FE group.

CONCLUSION

Our findings suggested a trend toward favouring frozen-thawed FTE might be a preferred transfer strategy for patients with IVF.

Does fresh or frozen embryo transfer affect imprinted gene expressions in human term placenta?

Our research aimed to compare the epigenetic alterations between placentae of in vitro fertilization (IVF) patients and spontaneous pregnancies. Additionally, the expression levels of proliferation markers (PCNA, Ki67) and glucose transporter proteins (GLUT1, GLUT3) were assessed in control and IVF placentae to examine the possible consequences of epigenetic alterations on placental development. Control group placentae were obtained from spontaneous pregnancies of healthy women (n = 16). IVF placentae were obtained from fresh (n = 16) and frozen (n = 16) embryo transfer pregnancies. A group of maternal and paternal imprint genes H19, IGF2, IGF2, IGF2R, PHLDA2, PLAGL1, MASH2, GRB10, PEG1, PEG3, and PEG10 were detected by Real-Time PCR. Additionally, PCNA, Ki67, GLUT1, and GLUT3 protein levels were assessed by immunohistochemistry and western blot. In the fresh embryo transfer placenta group (fETP), gene expression of paternal PEG1 and PEG10 was upregulated compared with the control group. Increased gene expression in paternal PEG1 and maternal IGFR2 genes was detected in the frozen embryo transfer placenta group (FET) compared with the control group. Conversely, expression levels of H19 and IGF2 genes were downregulated in the FET group. On the other hand, GLUT3 and PCNA expression was increased in FET group placentae. IVF techniques affect placental imprinted gene expressions which are important for proper placental development. Imprinted genes are differently expressed in fresh ET placentae and frozen ET placentae. In conclusion, these data indicate that altered imprinted gene expression may affect glucose transport and cell proliferation, therefore play an important role in placental development.

Prolonged Cryopreservation Negatively Affects Embryo Transfer Outcomes Following the Elective Freeze-All Strategy: A Multicenter Retrospective Study

BACKGROUND

With the development of embryo freezing and warming technology, frozen-thawed embryo transfer (FET) has been widely utilized. However, studies investigating the association between cryopreservation duration and FET outcomes are limited and controversial, and previous studies did not conduct stratification analyses based on demographic or clinical characteristics.

METHODS

This multicenter retrospective study included 17,826 women who underwent their first FET following the freeze-all strategy during the period from January 2014 to December 2018. Duration of cryopreservation was categorized into five groups: 3-8 weeks, 8-12 weeks, 12-26 weeks, 26-52 weeks, and >52 weeks. Modified Poisson regression and multivariate logistic regression were used to assess the association between cryostorage time of vitrified embryos and transfer outcomes. Moreover, further stratification analyses were performed according to variables with p <0.05 in multivariate models.

RESULTS

In this large multicenter study, we observed that storage duration was inversely associated with the possibility of pregnancy and live birth (p <0.001), but not with the risk of ectopic pregnancy and miscarriage. Stratification analyses based on maternal age, the number of oocytes retrieved, and condition of embryo transferred indicated that the inverse correlation was significant in the subpopulation with characteristics: (1) less than 40 years old, (2) more than 3 oocytes retrieved, and (3) only high-quality blastocysts transferred.

CONCLUSION

The results of this large, multicenter, retrospective study suggested that prolonged cryopreservation was inversely associated with the probability of pregnancy and live birth. Therefore, for patients who adopt a freeze-all strategy, early FET might achieve a better outcome.

Endometrial thickness is associated with incidence of small-for-gestational-age infants in fresh in vitro fertilization-intracytoplasmic sperm injection and embryo transfer cycles

OBJECTIVE

To investigate whether endometrial thickness (EMT) is associated with adverse obstetric and neonatal outcomes in fresh in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) cycles.

DESIGN

Retrospective cohort study.

SETTING

University-based reproductive medical center.

PATIENT(S)

Women under the age of 42 years who underwent IVF/ICSI treatment and received fresh ET in our unit from January 2017 to December 2018, resulting in a live singleton birth.

INTERVENTION(S)

Controlled ovarian hyperstimulation and IVF/ICSI; fresh ET.

MAIN OUTCOME MEASURE(S)

Birth weight, gestational age, small for gestational age (SGA), large for gestational age (LGA), placenta previa, placental abruption, hypertensive disorders, and gestational diabetes mellitus.

RESULT(S)

The risk of being born SGA was statistically significantly increased in the EMT ≤7.5 mm group compared with those from the EMT >12 mm group (adjusted odds ratio [aOR] 2.391; 95% confidence interval [CI], 1.155-4.950). Moreover, maternal body mass index, secondary infertility, preterm delivery, and hypertensive disorders were all independent predictors for SGA. The mean birth weights of singletons in women with EMT ≤7.5 mm were lower than in the groups with EMT >7.5-12 mm and EMT >12 mm (3.25 ± 0.56 kg vs. 3.38 ± 0.51 kg and 3.39 ± 0.53 kg, respectively).

CONCLUSION(S)

After fresh IVF/ICSI-ET, the risk of SGA was increased twofold in women with EMT ≤7.5 mm compared with women with EMT >12 mm. We suggest that women with a thin EMT after obtaining a pregnancy by IVF should receive improved prenatal care to reduce the risk of delivering a SGA infant.

The Future of Cryopreservation in Assisted Reproductive Technologies

Societal changes and the increasing desire and opportunity to preserve fertility have increased the demand for effective assisted reproductive technologies (ART) and have increased the range of scenarios in which ART is now used. In recent years, the "freeze-all" strategy of cryopreserving all oocytes or good quality embryos produced in an IVF cycle to transfer later-at a time that is more appropriate for reasons of medical need, efficacy, or desirability-has emerged as an accepted and valuable alternative to fresh embryo transfer. Indeed, improvements in cryopreservation techniques (vitrification) and the development of more efficient ovarian stimulation protocols have facilitated a dramatic increase in the practice of elective frozen embryo transfer (eFET). Alongside these advances, debate continues about whether eFET should be a standard treatment option available to the whole IVF population or if it is important to identify patient subgroups who are most likely to benefit from such an approach. Achieving successful outcomes in ART, whether by fresh or frozen embryo transfer, is influenced by a wide range of factors. As well as the efficiency of IVF and embryo transfer protocols and techniques, factors affecting implantation include maternal aging, sperm quality, the vaginal and endometrial microbiome, and peri-implantation levels of serum progesterone. The safety of eFET, both during ART cycles and on longer-term obstetric and neonatal outcomes, is also an important consideration. In this review, we explore the benefits and risks of freeze-all strategies in different scenarios. We review available evidence on the outcomes achieved with elective cryopreservation strategies and practices and how these compare with more traditional IVF cycles with fresh embryo transfers, both in the general IVF population and in subgroups of special interest. In addition, we consider how to optimize and individualize "freeze-all" procedures to achieve successful reproductive outcomes.

Interpregnancy interval and singleton pregnancy outcomes after frozen embryo transfer

OBJECTIVE

To describe the relationship between interpregnancy interval (IPI) and perinatal outcomes in singleton live births after frozen embryo transfer (FET).

DESIGN

Retrospective analysis of the Society for Assisted Reproductive Technology Clinical Outcome Reporting System cohort including patients with a history of live birth from ART who returned for an FET cycle between 2004 and 2013.

SETTING

Not applicable.

PATIENT(S)

A total of 19,270 singleton live births from FET subsequent to a live birth.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Odds for preterm delivery (<37, <34, <28 weeks) and low birth weight (<2,500, <1,500 g) adjusted for age, body mass index, and history of prior preterm delivery.

RESULT(S)

Of 74,456 autologous FET cycles following an index live birth, 24,091 resulted in a repeat live birth, with 19,270 singleton live births. An IPI of <12 months occurred in 19% of cycles. Adjusted odds (aORs) for preterm delivery at <37 weeks were significantly increased for an IPI of <6 months (aOR 2.05, 95% confidence interval [CI] 1.48-2.84), 6 to <12 months (aOR 1.26, 95% CI 1.06-1.49), and 18 to <24 months (aOR 1.23, 95% CI 1.06-1.43) when compared with the reference interval of 12 to <18 months. Additionally, an IPI of <6 months was associated with increased odds for low birth weight (aOR 3.06, 95% CI 2.07-4.52) and very low birth weight (aOR 5.65, 95% CI 2.96-10.84) compared with an IPI of 12 to <18 months.

CONCLUSION(S)

In this nationally representative population, an interval from delivery to start of an FET cycle of <12 months is associated with increased odds for preterm delivery among singleton live births. Consistent with data for patients undergoing fresh IVF, the data support delaying FET 12 months from a live birth.

Changes in DNA methylation and imprinting disorders in E9.5 mouse fetuses and placentas derived from vitrified eight-cell embryos

Vitrification is increasingly used in assisted reproductive technology (ART) laboratories worldwide, and potential vitrification-induced risks require further exploration. The effect of vitrification on changes in DNA methylation and imprinting disorders was investigated in E9.5 mouse fetuses and placentas. Fetus and placental tissues were collected from the natural mating (nautural conception [NC]) group, in vitro culture (IVC) group and vitrified embryo transfer (VET) group. The fetal crown-rump length at E9.5 in both the IVC (0.210 ± 0.059 mm) and VET (0.205 ± 0.048 mm) groups was significantly reduced compared with the NC group (0.288 ± 0.083 mm). The global methylation levels of fetuses were decreased in the IVC group compared with the NC group and it was increased after vitrification compared with IVC (p < 0.05), similar to what was observed in the NC group (p > 0.05). The changes could be attributed to the disorders of DNA methyltransferases and ten-eleven translocations. In the IVC and VET fetuses, a majority of maternally expressed genes were upregulated, which repressed fetal growth. Furthermore, vitrification led to a change in the methylation level of KvDMR1, which resulted in the disturbance of gene imprinting. According to our results, vitrification could contribute to increased methylation compared with IVC and contributes to a gene imprinting disorder rather than recovery. Despite the routine use of embryo vitrification in clinical settings, the effect that this procedure may have on genomic imprinting deserves much greater attention.

Fresh versus frozen embryo transfer for full-term singleton birth: a retrospective cohort study

Background

Improvements in vitrification and frozen embryo transfer (FET) technologies have rapidly increased, and some evidence suggests that FET may increase pregnancy rates and lead to more favourable perinatal outcomes. However, the outcome of interest should be offspring safety. Therefore, the primary objective of our study was to investigate whether FET was preferable to fresh embryo transfer (ET) in terms of full-term neonatal birthweight and congenital malformations.

Methods

This was a retrospective cohort study of patients with no pregnancy-related complications who underwent first fresh ETs (n = 2059) or FETs (n = 2053), resulting in full-term singletons births. Outcome measures were neonatal birthweight, low birthweight (LBW), small-for-gestational age (SGA), large-for-gestational age (LGA), macrosomia and congenital malformations. Additionally, we used logistic regression to adjust for baseline characteristics (age, BMI, No. of embryos transferred and embryo stage) between the two groups.

Results

The mean neonatal birthweight was higher for singletons born after FET than for singletons born after fresh ET (3468.7 ± 475.3 vs. 3386.7 ± 448.1; p < 0.001). The frequencies of full-term singleton LBW and SGA after FET were significantly lower than those after fresh ET (1.7% vs. 3.0 and 4.4% vs. 6.7%, respectively), with adjusted rate ratios of 0.59 (95% CI, 0.37 to 0.98; p = 0.026) and 0.73 (95% CI, 0.55 to 0.99; p = 0.041), respectively. FET resulted in higher frequencies of macrosomia and LGA (15.1% vs 10.2 and 22.8% vs. 17.5%, respectively) than fresh ET, with adjusted rate ratios of 1.43 (95% CI, 1.16 to 1.75; p = 0.001) and 1.26 (95% CI, 1.07 to 1.49; p = 0.007), respectively. Furthermore, the incidence of congenital malformations was not different between the two groups (1.2% vs. 0.9%), with a rate ratio of 0.288.

Conclusions

After the cycles with pregnancy-related complications were excluded and after adjustments for baseline characteristics, women undergoing FET were associated with a higher neonatal birthweight than women undergoing fresh ET cycles. Additionally, the FET protocol was associated with lower rates of LBW and SGA and higher rates of macrosomia and LGA than the fresh ET protocol. Meanwhile, no difference in the congenital malformation rate was evident between the two groups.

First trimester pregnancy ultrasound findings as a function of method of conception in an infertile population

PURPOSE

The aim of this study was to determine whether first trimester ultrasound measurements of crown rump length (CRL) and gestational sac diameter (GSD) differ depending on the method of conception among infertile women.

METHOD

Infertile women, ages 21-50 years old, who conceived viable, singleton pregnancies via fresh embryo transfer (ET), frozen ET, non-in vitro fertilization (IVF) fertility treatment, or spontaneously were included in this observational cohort study at an academic fertility practice. Embryonic growth trajectories defined by the CRL and GSD at 6 and 8 weeks' gestation were analyzed and compared among the methods of conception.

RESULTS

Crown rump length at 6 weeks' gestation was smaller for conceptions achieved via fresh ET compared with frozen ET in a natural cycle (1.50 vs. 2.50 mm, p = 0.017). Crown rump length was smaller at 8 weeks' gestation in conceptions achieved via fresh ET compared to frozen ET in a programmed cycle (16.13 vs. 17.02 mm, p = 0.039).

CONCLUSION

Among infertile women, embryo growth may differ between fresh and frozen ET as early as 6 and 8 weeks' gestation.

[Pregnancy and obstetric outcomes of fresh embryo transfer versus frozen-thawed embryo transfer in women below 35 years of age]

OBJECTIVE

To compare the obstetric and perinatal outcomes between fresh embryo transfer (ET) and frozen-thawed ET (the "freeze-all" strategy) and evaluate the benefits of the "freeze-all" embryo strategy for young patients.

METHODS

We reviewed a total of 2091 ET cycles performed between January, 2011 and December, 2015 in women aged 20-35 years, including 1295 fresh ET cycles and 796 frozen-thawed ET cycles. The demographic characteristics, ovarian stimulation syndrome, clinical pregnancy rates, live birth rate and the obstetric outcomes (gestational age, preterm delivery rate and mean birth weight) were compared between the two groups.

RESULTS

The mean age of the patients receiving frozen-thawed ET cycles had a significantly younger age than those having fresh ET cycles (29.5 vs 30.2 years, P<0.05); the patients undergoing frozen-thawed ET cycles also had significantly higher estradiol level on the day of trigger (12 973 pmol/L vs 8673 pmol/L) and a greater oocyte number retrieved (12.7 vs 8.7). The incidence of severe ovarian hyperstimulation syndrome was significantly lower in patients with frozen ET than those with fresh ET (P<0.05). No significant differences were found in the pregnancy rate (59.5% vs 56.0%; P>0.05), live birth rate (50.3% vs 47.0%; P>0.05), mean birth weight or gestational age between the two groups.

CONCLUSIONS

The freeze-all policy produces similar pregnancy and obstetric outcomes with those of fresh ET. Our results support the hypothesis that the freeze-all strategy help to prevent OHSS with a good pregnancy rate.

Elevated progesterone and its impact on birth weight after fresh embryo transfers

PURPOSE

The purpose of the study was to examine the association between serum progesterone levels on the day of hCG administration and birth weight among singleton live births after fresh embryo transfer.

METHODS

This study was conducted as a retrospective cohort database analysis on patients who underwent IVF treatment cycles from January 2004 to April 2012. The study was performed at a University affiliated private infertility practice. All cycles that had achieved a singleton live birth after fresh embryo transfer and for which progesterone was measured on the day of hCG administration were examined. Generalized linear models were used to calculate mean birth weight and z-scores.

RESULTS

We analyzed 817 fresh IVF embryo transfers in which birth weight, gestational age, and progesterone (ng/mL) level on day of hCG administration were documented. While there was a decrease in birth weight as progesterone quartile [≤0.54; >0.54 to ≤0.81; >0.81 to ≤1.17; >1.17 ng/mL] increased, the difference in mean birth weights among the four quartiles was not statistically significant (p = 0.11) after adjusting for maternal age and peak estradiol levels. When dichotomizing based on a serum progesterone considered clinically elevated, cycles with progesterone >2.0 ng/mL had a significantly lower mean singleton birth weight (2860 g (95% CI 2642 g, 3079 g)) compared to cycles with progesterone ≤2.0 ng/mL (3167 g (95% CI 3122 g, 3211 g) p = 0.007)) after adjusting for maternal age and estradiol.

CONCLUSION

We demonstrated that caution should be exercised when performing fresh embryo transfers with elevated progesterone levels and in particular with levels (>2.0 ng/mL) as this may lead to lower birth weight.

Abnormal implantation after fresh and frozen in vitro fertilization cycles

OBJECTIVE

To determine whether fresh embryo transfers are at a higher risk of abnormal implantation compared with frozen embryo transfers while accounting for the embryo stage at transfer.

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

We used data from the Society for Assisted Reproductive Technologies to identify all fresh and frozen autologous IVF cycles from 2004-2013 resulting in a positive pregnancy test. The cycles were parameterized into a four-level predictor of [1] fresh blastocyst transfer, [2] fresh non-blastocyst transfer, [3] frozen blastocyst transfer, and [4] frozen non-blastocyst transfer.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

We examined a composite outcome of abnormal implantation, defined as biochemical pregnancy, ectopic/heterotopic pregnancy, and first-trimester pregnancy loss. Regression modeling was performed with repeated measures multivariable logistic regression, adjusted for age, parity, number of embryos transferred, infertility diagnosis, and calendar year of treatment.

RESULT(S)

Of 509,938 cycles analyzed, 31.8% resulted in abnormal implantation. Compared with a fresh blastocyst transfer, a fresh non-blastocyst transfer had a 22% increase risk of abnormal implantation, a frozen blastocyst transfer had a 36% increase risk, and a frozen non-blastocyst transfer had a 57% increase risk. When individual outcomes were analyzed, fresh embryo transfers had a lower risk of biochemical pregnancy and pregnancy loss but a higher risk for ectopic/heterotopic pregnancy.

CONCLUSION(S)

Fresh blastocyst transfers had the lowest overall risk of abnormal implantation but a higher risk of ectopic/heterotopic pregnancy. Although embryo cryopreservation is indicated in certain treatment cycles, elective embryo cryopreservation may not be the optimal strategy to adopt for all cycles.

Optimal euploid embryo transfer strategy, fresh versus frozen, after preimplantation genetic screening with next generation sequencing: a randomized controlled trial

OBJECTIVE

To compare two commonly used protocols (fresh vs. vitrified) used to transfer euploid blastocysts after IVF with preimplantation genetic screening.

DESIGN

Randomized controlled trial.

SETTING

Private assisted reproduction center.

PATIENT(S)

A total of 179 patients undergoing IVF treatment using preimplantation genetic screening.

INTERVENTION(S)

Patients were randomized at the time of hCG administration to either a freeze-all cycle or a fresh day 6 ET during the stimulated cycle.

MAIN OUTCOME MEASURE(S)

Implantation rates (sac/embryo transferred), ongoing pregnancy rates (PRs) (beyond 8 weeks), and live birth rate per ET in the primary transfer cycle.

RESULT(S)

Implantation rate per embryo transferred showed an improvement in the frozen group compared with the fresh group, but not significantly (75% vs. 67%). The ongoing PR (80% vs. 61%) and live birth rates (77% vs. 59%) were significantly higher in the frozen group compared with the fresh group.

CONCLUSION(S)

Either treatment protocol investigated in the present study can be a reasonable option for patients. Freezing all embryos allows for inclusion of all blastocysts in the cohort of embryos available for transfer, which also results in a higher proportion of patients reaching ET. These findings suggest a trend toward favoring the freeze-all option as a preferred transfer strategy when using known euploid embryos.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02000349.