Comparisons of benefits and risks of single embryo transfer versus double embryo transfer: a systematic review and meta-analysis

Effects of Various Transfer Strategies of Frozen-Thawed Cleavage-Stage and Blastocyst Embryos on Pregnancy and Neonatal Outcomes in Different Age Groups

Objective

The aim of this study is to assess the impact of different embryo transfer strategies, focusing on cleavage-stage embryos and blastocysts, on pregnancy and neonatal outcomes in frozen-thawed embryo transfer (FET) cycles among women < 35 years old and ≥ 35 years old.

Methods

A retrospective cohort analysis of 3,065 FET cycles performed between April 2015 and October 2022 categorized patients into seven groups by embryo morphology, quality, and quantity: single/double high-quality cleavage (A/B), single/double high-quality blastocyst (C/D), single/double poor-quality blastocyst (E/F), and mixed-quality blastocyst (G). Stratified by age (<35/≥35 years), outcomes (clinical pregnancy, live birth, multiple pregnancy, preterm birth) were analyzed using non-parametric tests and chi-square.

Results

In women <35 years, transferring two high-quality cleavage embryos (Group B) yielded higher clinical pregnancy (60.12% vs 28.57%) and live birth rates (51.45% vs 19.64%) than single high-quality cleavage embryos (Group A; P < 0.05). For blastocyst transfer, double high-quality blastocysts (Group D) showed higher multiple pregnancy and preterm birth rates than single high-quality blastocysts (Group C; P < 0.05). In women ≥35 years, Group B had superior pregnancy outcomes compared to Group A, while Group D demonstrated significantly higher clinical pregnancy and live birth rates than Group C (P < 0.05). Transferring two poor-quality blastocysts (Group F) improved live birth rates in older patients compared to single poor-quality blastocysts (Group E; 31.91% vs 14.29%, P < 0.05). No significant differences in neonatal birth weight were observed across age groups.

Conclusion

For FET cycles, transferring two high-quality cleavage embryos is recommended for all ages. Women <35 years should prioritize single high-quality blastocyst transfer to minimize multiple pregnancies and preterm births, while those ≥35 years benefit from double high-quality blastocysts. Transferring two poor-quality blastocysts may enhance pregnancy outcomes in older patients. These findings warrant validation through multicenter studies to ensure clinical applicability.

High multiple pregnancy rates after double embryo transfers in human: a retrospective cohort study

Abstract

To improve clinical outcomes of human medically assisted reproduction, the transfer of multiple embryos is frequently performed. This leads to high rates of multiple pregnancies. In this study we explored if a cohort of patients can be defined, that benefits from the transfer of two embryos while mitigating the odds of multiple pregnancies by considering female patients' age, embryo quality and embryo cohort quality. In this retrospective cohort study, clinical pregnancy rate (CPR), live birth rate (LBR) and multiple pregnancy rate (MPR) after fresh single embryo transfers (SETs, n = 245) were compared to those after double embryo transfer (DET, n = 278). Female patient's age, embryo quality and embryo cohort quality were used to explore clinical outcomes in subgroups. Overall, this study found that compared to SET, DET significantly increased the CPR (33.5 vs 49.6%, adjusted odds ratio (aOR): 2.233, 95% CI: 1.529-3.261, P < 0.001), LBR (24.1 vs 39.2%, aOR: 2.416, 1.605-3.636, P < 0.001) and MPR (0.0 vs 25.4%, P < 0.001). Subgroup analysis based on female age, embryo quality and further stratification based on embryo cohort score revealed that the MPR in all subgroups was high after DET and a subgroup with significantly reduced MPR after DET could not be defined. In conclusion, DETs are associated with high MPRs that cannot be avoided by considering female patients' age, embryo quality and embryo cohort quality. SET is the most effective way to avoid a multiple pregnancy.

Lay summary

This study examined whether it is possible to avoid multiple pregnancies in treatments of assisted reproduction when two embryos are transferred to certain patients. Transferring more than one embryo can increase the chances of pregnancy and live birth but also raises the risk of multiple pregnancies. Multiple pregnancies are linked to health risks for both the mother and the children. Using data from a single clinic, this study explored whether there are specific patients who could benefit from the transfer of two embryos while still having a lower risk of multiple pregnancy. However, the researchers found that DETs consistently lead to high rates of multiple pregnancies, even when factors like the mother's age, embryo quality and overall embryo cohort quality are considered. The researchers concluded that transferring a single embryo remains the safest approach to prevent multiple pregnancies.

Chemical pregnancy in fresh and cryopreserved cycles, using day 3 (cleavage stage) and day 4 embryos (morula stage)

With the advancement in the embryo culture media, which supports nutrient requirements of embryos up to 5 to 6 days, there's a chance to select more viable embryos, which are more likely to result in pregnancy, compared to earlier stages. Also, there is a controversy regarding the frozen embryo transfer compared to the fresh type. To compare the chemical pregnancy rates between fresh embryo transfer (ET), and frozen embryo transfer (FET), on day 3 (cleavage), and day 4 (morula) of development. In this retrospective study, data of 242 fresh and 758 frozen embryo transfer cycles were obtained in one infertility center in Isfahan, Iran. The study's groups were assigned based on the day of fresh or frozen embryo transfer (day 3, or day 4 embryos) and the embryo grading. Chemical pregnancy was the main outcome measurement (implantation rates). The chemical pregnancy rate was higher in the good quality frozen embryo day 3 and transfer on day 4 group (40.1%). This rate was near the results of transferring the good quality frozen embryo on day 4 (39.2 %). There was no significant difference in the chemical pregnancy rate related to the number of transferred embryos (p = 0.55). The higher PRs, when the embryos were transferred on day 4, provided further support for the morula stage embryo transfer, possibly because of better synchrony with the endometrium. It is concluded that morula/compact embryos are good candidates for embryo transfer, which simultaneously reduces the number of transferred embryos.

Follicular fluid and plasma lipidome profiling and associations towards embryonic development outcomes during ART treatment

Introduction

It is well acknowledged that lipids assume a critical role in oocyte maturation and early embryonic metabolism, this study aimed to evaluate the relationship between the lipid composition of plasma and follicular fluid (FF), and the consequences of embryonic development. This study compared the lipidomic profiles of paired plasma and FF samples obtained from sixty-five Chinese women who underwent assisted reproductive technology (ART) treatments.

Methods

Non-targeted lipidomics analysis.

Result

Results not only indicated similarities in lipid composition between these biofluids, but also revealed a number of unique differences. The biomatrix distinction was found to be primarily driven by lipids belonging to the lysophosphatidylcholines (LPC), phosphatidylethanolamines (PE), ether PE, and triglyceride (TG) classes. In addition, specific species from these subclasses were discovered to be correlated with embryo development outcomes during ART. Notably, the composition of the fatty acyl chains appeared to play a crucial role in these associations. Furthermore, thirteen plasma lipid variables were identified, represented by Phosphatidylcholine 18:014:0 and PE P-18:020:1, which correlated with successful blastocyst formation (BF).

Discussion

The present study demonstrated that FF has a distinctive lipid composition, setting it apart from plasma; and the association observed with embryonic development underscored an important role of lipid composition in the healthy development of oocytes.

Effect of GnRH agonist down-regulation combined with hormone replacement treatment on reproductive outcomes of frozen blastocyst transfer cycles in women of different ages

Objective

To investigate the effect of GnRH agonist (GnRH-a) down-regulation prior to hormone replacement treatment (HRT) to prepare the endometrium in frozen embryo transfer (FET) cycles in women of different ages.

Methods

This was a retrospective study, and after excluding patients with adenomyosis, endometriosis, severe endometrial adhesions, polycystic ovary syndrome (PCOS), and repeated embryo implantation failures, a total of 4,091 HRT cycles were collected. Patients were divided into group A (<35 years old) and group B (≥35 years old), and each group was further divided into HRT and GnRHa-HRT groups. The clinical outcomes were compared between groups.

Results

There was no statistically significant difference in clinical outcomes between the HRT and GnRHa-HRT groups among women aged <35 years. In women of advanced age, higher rates of clinical pregnancy and live birth were seen in the GnRHa-HRT group. Logistic regression analysis showed that female age and number of embryos transferred influenced the live birth rate in FET cycles, and in women aged ≥ 35 years, the use of GnRH-a down-regulation prior to HRT improved pregnancy outcomes.

Conclusions

In elderly woman without adenomyosis, endometriosis, PCOS, severe uterine adhesions, and RIF, hormone replacement treatment with GnRH agonist for pituitary suppression can improve the live birth rate of FET cycles.

Comparison of pregnancy outcomes among patients of different ages who underwent frozen-thawed high-quality single blastocyst transfer

OBJECTIVE

To investigate the feasibility of performing frozen-thawed high-quality single blastocyst transfer in women of different ages.

METHODS

A total of 1,279 women were divided into four groups: a 38-40-year-old group (n = 147), 35-37-year-old group (n = 164), 30-34-year-old group (n = 483), and < 30-year-old group (n = 485). Intergroup comparisons of baseline characteristics and pregnancy and neonatal outcomes were made.

RESULTS

The clinical pregnancy rate (47.6%), and live birth rate (34.0%) in the 38-40-year-old group were significantly lower than those in the 30-34-year-old group (64.4%, 50.9%, respectively; all P < 0.001) and < 30-year-old group (62.9%, 50.7%, respectively; all P < 0.001). However, the 35-37-year-old group did not differ from the other three groups in these two dimensions (all P > 0.05). Moreover, there were no differences in the rates of biochemical pregnancy, miscarriage, or obstetric or neonatal complications among the four groups (all P > 0.05). According to the multivariate logistic regression analysis, the 35-37-year-old group was not associated with non-live birth outcomes, adverse pregnancy outcomes, or obstetric or neonatal complications. However, being 38-40 years of age was a risk factor for non-live birth (OR = 2.121, 95% CI: 1.233-3.647) and adverse pregnancy outcomes (OR = 1.630, 95% CI: 1.010-2.633). Post hoc power analysis showed that the study was sufficiently powered to detect meaningful differences.

CONCLUSION

Frozen-thawed high-quality single blastocyst transfer produces the same satisfactory pregnancy outcomes for women aged 35-37 years as younger patients. Future prospective randomized controlled studies with larger populations are needed to verify the feasibility and safety of this method.

ESHRE guideline: number of embryos to transfer during IVF/ICSI†

STUDY QUESTION

Which clinical and embryological factors should be considered to apply double embryo transfer (DET) instead of elective single embryo transfer (eSET)?

SUMMARY ANSWER

No clinical or embryological factor per se justifies a recommendation of DET instead of eSET in IVF/ICSI.

WHAT IS KNOWN ALREADY

DET is correlated with a higher rate of multiple pregnancy, leading to a subsequent increase in complications for both mother and babies. These complications include preterm birth, low birthweight, and other perinatal adverse outcomes. To mitigate the risks associated with multiple pregnancy, eSET is recommended by international and national professional organizations as the preferred approach in ART.

STUDY DESIGN, SIZE, DURATION

The guideline was developed according to the structured methodology for development and update of ESHRE guidelines. Literature searches were performed in PUBMED/MEDLINE and Cochrane databases, and relevant papers published up to May 2023, written in English, were included. Live birth rate, cumulative live birth rate, and multiple pregnancy rate were considered as critical outcomes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Based on the collected evidence, recommendations were discussed until a consensus was reached within the Guideline Development Group (GDG). A stakeholder review was organized after the guideline draft was finalized. The final version was approved by the GDG and the ESHRE Executive Committee.

MAIN RESULTS AND THE ROLE OF CHANCE

The guideline provides 35 recommendations on the medical and non-medical risks associated with multiple pregnancies and on the clinical and embryological factors to be considered when deciding on the number of embryos to transfer. These recommendations include 25 evidence-based recommendations, of which 24 were formulated as strong recommendations and one as conditional, and 10 good practice points. Of the evidence-based recommendations, seven (28%) were supported by moderate-quality evidence. The remaining recommendations were supported by low (three recommendations; 12%), or very low-quality evidence (15 recommendations; 60%). Owing to the lack of evidence-based research, the guideline also clearly mentions recommendations for future studies.

LIMITATIONS, REASONS FOR CAUTION

The guideline assessed different factors one by one based on existing evidence. However, in real life, clinicians' decisions are based on several prognostic factors related to each patient's case. Furthermore, the evidence from randomized controlled trials is too scarce to formulate high-quality evidence-based recommendations.

WIDER IMPLICATIONS OF THE FINDINGS

The guideline provides health professionals with clear advice on best practice in the decision-making process during IVF/ICSI, based on the best evidence currently available, and recommendations on relevant information that should be communicated to patients. In addition, a list of research recommendations is provided to stimulate further studies in the field.

STUDY FUNDING/COMPETING INTEREST(S)

The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, the literature searches, and the dissemination of the guideline. The guideline group members did not receive payment. DPB declared receiving honoraria for lectures from Merck, Ferring, and Gedeon Richter. She is a member of ESHRE EXCO, and the Mediterranean Society for reproductive medicine and the president of the Croatian Society for Gynaecological Endocrinology and Reproductive Medicine. CDG is the past Chair of the ESHRE EIM Consortium and a paid deputy member of the Editorial board of Human Reproduction. IR declared receiving reimbursement from ESHRE and EDCD for attending meetings. She holds an unpaid leadership role in OBBCSSR, ECDC Sohonet, and AER. KAR-W declared receiving grants for clinical researchers and funding provision to the institution from the Swedish Cancer Society (200170F), the Senior Clinical Investigator Award, Radiumhemmets Forskningsfonder (Dnr: 201313), Stockholm County Council FoU (FoUI-953912) and Karolinska Institutet (Dnr 2020-01963), NovoNordisk, Merck and Ferring Pharmaceuticals. She received consulting fees from the Swedish Ministry of Health and Welfare. She received honoraria from Roche, Pfizer, and Organon for chairmanship and lectures. She received support from Organon for attending meetings. She participated in advisory boards for Merck, Nordic countries, and Ferring. She declared receiving time-lapse equipment and grants with payment to institution for pre-clinical research from Merck pharmaceuticals and from Ferring. SS-R received research funding from Roche Diagnostics, Organon/MSD, Theramex, and Gedeo-Richter. He received consulting fees from Organon/MSD, Ferring Pharmaceuticals, and Merck Serono. He declared receiving honoraria for lectures from Ferring Pharmaceuticals, Besins, Organon/MSD, Theramex, and Gedeon Richter. He received support for attending Gedeon Richter meetings and participated in the Data Safety Monitoring Board of the T-TRANSPORT trial. He is the Deputy of ESHRE SQART special interest group. He holds stock options in IVI Lisboa and received equipment and other services from Roche Diagnostics and Ferring Pharmaceuticals. KT declared receiving payment for honoraria for giving lectures from Merck Serono and Organon. She is member of the safety advisory board of EDQM. She holds a leadership role in the ICCBBA board of directors. ZV received reimbursement from ESHRE for attending meetings. She also received research grants from ESHRE and Juhani Aaltonen Foundation. She is the coordinator of EHSRE SQART special interest group. The other authors have no conflicts of interest to declare.

DISCLAIMER

This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgement to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose (full disclaimer available at https://www.eshre.eu/Guidelines-and-Legal).

Comparison of miscarriage rates in low prognosis patients according to the POSEIDON criteria

OBJECTIVE

The POSEIDON criteria stratified patients with poor ovarian response into four subgroups with exclusive characteristics and assisted reproductive technology success rates. However, limited studies focused on miscarriage in the POSEIDON population. This study aimed to explore whether the miscarriage rate different among low prognosis patients according to POSEIDON criteria.

MATERIALS AND METHODS

This is a retrospective observational study. All clinical pregnancies achieved after in vitro fertilization or intracytoplasmic sperm injection treatment between January 1998 and April 2021 were analyzed. The primary outcome was miscarriage, defined as the pregnancy loss before 20 weeks of gestation age. Miscarriage rate was estimated per clinical pregnancy and gestational sac.

RESULTS

A total of 1222 clinical pregnancies from 1088 POSEIDON patients met the inclusion criteria. The miscarriage rates per clinical pregnancy in each POSEIDON subgroup were as follows: Group 1: 11.7 %, Group 2: 26.5 %, Group 3: 20.9 %, and Group 4: 37.5 %. The miscarriage rate per gestational sac showed a similar trend as the clinical miscarriage rate. Multivariate regression analysis showed that advanced maternal age is an independent factor for miscarriage (Group 2 vs. 1: OR 2.476; Group 4 vs. 3: OR 2.252). Patients with diminished ovarian reserve (DOR) have higher miscarriage risks but without significance (Group 3 vs. 1: OR 1.322; Group 4 vs. 2: OR 1.202).

CONCLUSION

Miscarriage rates differed among low prognosis patients according to the POSEIDON criteria. Age remains a determined risk for miscarriage. DOR might be a potential factor for miscarriage, but it didn't account for a significant impact in POSEIDON patients.

Embryo Transfer Procedural Parameters Do Not Predict IVF Cycle Outcome

BACKGROUND

this study aims to assess the effect of embryo transfer (ET) performance parameters of a technical nature on IVF outcome.

METHODS

A total of 1417 ETs from a single IVF center were included in this prospective observational study. The parameters investigated were as follows: the presence of cervical mucus post catheter withdrawal, the presence of blood, catheter reload, the employment of a tenaculum and stylet, catheter resistance as experienced by the physician and patient discomfort.

RESULTS

When ET performance parameters were associated with clinical outcomes on a singular level, none of the ET parameters presented with any statistical significance. The evaluation of covariates indicated that the number and the quality of transferred embryos, as well as maternal age, exerted a statistically significant effect on clinical outcomes. In a multivariate analysis, only the presence of mucus along with significant catheter resistance presented with statistical significance; however, when adjusting for covariates, this combination showed no statistically significant effect on clinical outcomes.

CONCLUSIONS

the results indicate that the time-consuming process of recording and analyzing ET performance parameters fails to offer any additional value in predicting the cycle's outcome, while factors like embryo quality and number, as well as maternal age, seem to be the sole robust predictive factors of an IVF cycle.

Effect of frozen-thawed embryo transfer with a poor-quality embryo and a good-quality embryo on pregnancy and neonatal outcomes

BACKGROUND

To evaluate the impact of embryo quality and quantity, specifically a poor quality embryo (PQE) in combination with a good quality embryo (GQE), by double embryo transfer (DET) on the live birth rate (LBR) and neonatal outcomes in patients undergoing frozen-thawed embryo transfer (FET) cycles.

METHODS

A study on a cohort of women who underwent a total of 1462 frozen-thawed cleavage or blastocyst embryo transfer cycles with autologous oocytes was conducted between January 2018 and December 2021. To compare the outcomes between single embryo transfer (SET) with a GQE and DET with a GQE and a PQE, propensity score matching (PSM) was applied to control for potential confounders, and a generalized estimating equation (GEE) model was used to determine the association between the effect of an additional PQE and the outcomes. Subgroup analysis was also performed for patients stratified by female age.

RESULTS

After PS matching, DET-GQE + PQE did not significantly alter the LBR (adjusted odds ratio [OR] 1.421, 95% CI 0.907-2.228) compared with SET-GQE in cleavage-stage embryo transfer but did increase the multiple birth rate (MBR, [OR] 3.917, 95% CI 1.189-12.911). However, in patients who underwent blastocyst-stage embryo transfer, adding a second PQE increased the live birth rate by 7.8% ([OR] 1.477, 95% CI 1.046-2.086) and the multiple birth rate by 19.6% ([OR] 28.355, 95% CI 3.926-204.790), and resulted in adverse neonatal outcomes. For patients who underwent cleavage-stage embryo transfer, transferring a PQE with a GQE led to a significant increase in the MBR ([OR] 4.724, 95% CI 1.121-19.913) in women under 35 years old but not in the LBR ([OR] 1.227, 95% CI 0.719-2.092). The increases in LBR and MBR for DET-GQE + PQE compared with SET-GQE in women older than 35 years were nonsignificant toward. For patients who underwent blastocyst-stage embryo transfer, DET-GQE + PQE had a greater LBR ([OR] 1.803, 95% CI 1.165-2.789), MBR ([OR] 24.185, 95% CI 3.285-178.062) and preterm birth rate (PBR, [OR] 4.092, 95% CI 1.153-14.518) than did SET-GQE in women under 35 years old, while no significant impact on the LBR ([OR] 1.053, 95% CI 0.589-1.884) or MBR (0% vs. 8.3%) was observed in women older than 35 years.

CONCLUSIONS

The addition of a PQE has no significant benefit on the LBR but significantly increases the MBR in patients who underwent frozen-thawed cleavage-stage embryo transfer. However, for patients who underwent blastocyst-stage embryo transfer, DET-GQE + PQE resulted in an increase in both the LBR and MBR, which may lead to adverse neonatal outcomes. Thus, the benefits and risks of double blastocyst-stage embryo transfer should be balanced. In patients younger than 35 years, SET-GQE achieved satisfactory LBR either in cleavage-stage embryo transfer or blastocyst-stage embryo transfer, while DET-GQE + PQE resulted in a dramatically increased MBR. Considering the low LBR in women older than 35 years who underwent single cleavage-stage embryo transfer, selective single blastocyst-stage embryo transfer appears to be a more promising approach for reducing the risk of multiple live births and adverse neonatal outcomes.

Higher risk of preterm twin delivery among shorter nulliparous women

OBJECTIVE

To determine if maternal height in nulliparous women influences pregnancy results in twin pregnancies.

MATERIAL AND METHODS

Retrospective cohort analysis evaluating twin pregnancies followed at Centro Hospitalar Universitário Lisboa Central, between 1995 and 2020. Of the 2900 pregnancies followed in that period, 886 nulliparous women with dichorionic twin pregnancies were selected. Two groups were considered: A - maternal height <163 cm (

RESULT(S)

PTB rates decreased along increasing maternal height. The comparison between group A and group B revealed no statistically significant differences in maternal characteristics (age, mode of conception - spontaneous or ART pregnancies, or BMI). Statistically significant differences were found in mean gestational age at birth (35.1 ± 1.8 vs. 36.0 ± 2.6 wks), PTB rates < 32, 34 and 36 wks, OR: 3.2, 2.3 and 2.4 respectively, p < 0.01. Shorter women had a 1.7× and 2.6× increased risk for significantly low (<2500 g) and very low (<1500 g) newborn birth weight (BW), respectively, and a 40 % increased risk of Cesarian delivery. No significant differences were shown with respect to stillbirths, neonatal and perinatal deaths, which had a low incidence in this study. In ART pregnancies we found the same results regarding PTB rates and newborn birthweight in shorter women. In Logistic Regression analysis, maternal height

CONCLUSION

Increased pregnancy risk in nulliparous shorter women should be taken into consideration in double embryo transfers.

Collapse

Key Words

• Art
• Dichorionic twins
• Maternal height
• Nulliparous women
• Perinatal outcomes

Collapse

MESH Headings

• Pregnancy
• Infant, Newborn
• Female
• Humans
• Infant
• Pregnancy, Twin
• Stillbirth
• Retrospective Studies
• Cesarean Section/adverse effects
• Premature Birth/epidemiology
• Infant, Very Low Birth Weight
• Birth Weight

Collapse

Grants Collapse

Affiliation(s)

Teresinha Simões Department of Maternal-Fetal Medicine, Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Nova Medical School, Lisbon, Portugal; Department of Reproductive Medicine, Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Nova Medical School, Lisbon, Portugal.
Inês Pereira Department of Maternal-Fetal Medicine, Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central, Lisbon, Portugal
Laura Gomes Department of Maternal-Fetal Medicine, Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central, Lisbon, Portugal
Sofia Brás Department of Maternal-Fetal Medicine, Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central, Lisbon, Portugal
Isabel Nogueira Department of Maternal-Fetal Medicine, Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central, Lisbon, Portugal
Alexandra Queirós Department of Maternal-Fetal Medicine, Prenatal Diagnosis Unit Maternity Dr. Alfredo da Costa, Centro Hospitalar Lisboa Central and Nova Medical School, Lisbon, Portugal

Collapse

Clinical outcomes of vanishing twin syndrome and selective fetal reduction after double embryos transferred in IVF pregnancy: A propensity score matching study

OBJECTIVE

The purpose of this study was to analyze the influence of early vanishing twin syndrome (VTS) and selective fetal reduction (SEFR) on surviving singleton births in in-vitro fertilization (IVF) pregnancy.

METHODS

We collected patients who conceived through IVF and delivered singletons over the past six years. The VT group (n = 194) and SEFR group (n = 144) had underwent double embryos transferred (DET) and only one fetus was born, due to the subsequent one birth reduction. The SET group had one embryo transferred (SET) and gave birth to singleton. Using the propensity score matching (PSM) method to reduce confounding, the VT group and SEFR group were matched and compared with 570 and 576 singleton controls, respectively (SET-I/II group). Obstetric complications and neonatal outcomes were compared. In addition, quantity and quality of transferred embryos of VT (n = 194) and singleton groups (born with singleton after DET and matched with VT group by PSM, n = 554) were compared.

RESULTS

Compared with the SET-I group, VT group had increased incidence of severe obstetric complications, including severe preeclampsia (p = 0.031), oligohydramnios (p = 0.038) and polyhydramnios (p = 0.015). VT group was more likely to show more frequent small for gestational age (SGA) (p = 0.046) and very small for gestational age (VSGA) (p = 0.031). Newborns in the SEFR group had a significantly lower birth weight (p = 0.005) and were more likely to manifest as low birthweight (LBW) (p = 0.009) and very low birthweight (VLBW, birth weight < 1500 g) (p = 0.012), and the incidence of very large for gestational age (VLGA) was lower (p = 0.030), compared with the control group. There were more developmental abnormalities in newborns of VTS, for decreased incidence of SGA (OR 0.156, 95% CI 0.036-0.669), VSGA (OR 0.057, 95% CI 0.006-0.553) and VLGA (OR 0.415, 95% CI 0.212-0.815) in SEFR group. The good quality embryo rate was higher in VT group (72.7% vs. 63.3%, p = 0.001) compared with the singleton group.

CONCLUSIONS

DET with subsequent VTS/SEFR carried a higher rate of adverse clinical outcomes, and the VTS group had worse perinatal outcome compared with SEFR. Therefore, we recommend SET in ART.

Large-scale retrospective analysis of methodological factors affecting pregnancy rates after embryo transfer for in vitro fertilization

This study aimed to investigate the impact of methodological factors on pregnancy rates after embryo transfer (ET) for in vitro fertilization. This retrospective cross-sectional study was conducted between September 2020 and April 2022. A total of 2048 patients who underwent ultrasonography-guided first frozen embryo transfer (FET) or a fresh ET cycle due to infertility were included in the study. The effects of age, ET protocol (frozen or fresh), preimplantation genetic testing, number of embryos transferred (NET), and embryo fundus distance on pregnancy rate were investigated. The mean age of pregnant patients (31.51 ± 5.28) was significantly lower than that of non-pregnant patients (35.34 ± 6.39) (P < .001). Multiple regression analysis showed that women with lower age (P < .001), higher NET (P < .001), higher embryo fundus distance (P < .001), FET (P < .001), and preimplantation genetic testing (P = .012) had a significantly higher likelihood of pregnancy. Appropriate transfer depth, younger age, euploid embryo transfer, FET, and a higher NET can increase the likelihood of pregnancy. However, multiple factors must be considered when deciding the best protocol for a particular patient, including patient preference, costs and timing.

Comparison of frozen-thaw blastocyst transfer strategies in women aged 35-40 years: a retrospective study

Objective

To compare the effects of five different frozen-thaw embryo transfer (FET) strategies in women aged 35-40 years.

Methods

Data from 1,060 patients were divided into five groups according to the number and quality of transferred blastocysts: a high-quality single blastocyst group (group A, n= 303), a high-quality double blastocysts group (group B, n= 176), a high-quality plus poor-quality double blastocysts group (group C, n= 273), a poor-quality double blastocysts group (group D, n= 189), and a poor-quality single blastocyst group (group E, n= 119). Comparative analyses were then performed between groups with regard to primary conditions, pregnancy, and neonatal outcomes.

Results

Group A had the lowest twin pregnancy rate (1.97%) and incidence of low-birth-weight infants (3.45%), which were significantly different from groups B, C, and D. In addition, the preterm birth rate (7.89%), neonatal birth weight (3300 g [3000, 3637.5]), and neonatal birth age (39.14 weeks [38.43, 39.61]) in group A were different from those in groups B and C. Double blastocyst transfer (DBT) was associated with a 20.558-fold (Risk Ratio [RR]=20.558, 95% confidence interval [CI], 6.628-63.763) and 3.091-fold (RR=3.091, 95% CI, 1.69-5.653) increased risk of twin pregnancy and preterm delivery in unadjusted analysis, respectively, when compared with single blastocyst transfer (SBT). In the adjusted analysis, we observed similar risk estimates (adjusted RR=26.501, 95% CI, 8.503-82.592; adjusted RR=3.586, 95% CI, 1.899-6.769).

Conclusion

Although, high-quality SBT resulted in a lower live birth rate than high-quality DBT, it also significantly reduced the risk of adverse pregnancies, thus resulting in more benefits for both the mother and baby. Collectively, our data indicate that high-quality SBT remains the optimal FET strategy for women aged 35-40 years and warrants further clinical application.

Personalized versus standard frozen-thawed embryo transfer in IVF/ICSI cycles: a systematic review and meta-analysis

PURPOSE

To investigate whether personalized embryo transfer (pET) protocol guided by an endometrial receptivity array (ERA) can improve clinical outcomes of assisted reproduction.

METHODS

We searched PubMed, Embase, Web of Science, and the Cochrane library for studies in which analytical comparisons of outcomes of pET and standard embryo transfer (sET) groups were undertaken. The references to the included studies were also manually searched. The primary outcome was clinical pregnancy rate (CPR), and the secondary outcomes were live birth rate (LBR), human chorionic gonadotropin (HCG) positivity, biochemical pregnancy rate (BPR), miscarriage rate (MR), implantation rate (IR), and ongoing pregnancy rate (OPR).

RESULTS

Ten studies were included in the meta-analysis, including one randomized controlled trial (RCT) and nine cohort studies. We observed no significant difference in the primary outcome of CPR between the pET and sET groups in unselected patients (RR = 1.07; 95% confidence interval [CI], 0.87-1.30; P = 0.53; I2 = 89%). In terms of secondary outcomes, we likewise noted no significant differences between the groups. Further subgroup analyses indicated that the pET protocol not only significantly reduced the MR for poor-prognosis patients, but it also reduced the CPR in donor cycles, elevated the BPR for good-prognosis patients, non-preimplantation genetic testing (PGT), and programmed cycles, and decreased the proportion of women showing HCG positivity in non-PGT cycles.

CONCLUSIONS

This meta-analysis revealed that ERA appears to possess limited guidance in embryo transfer. More high-quality RCTs are therefore needed to investigate the clinical validity and feasibility of ERA in the future.

Pregnancy Outcomes for Day 5 Versus Day 6 Single Frozen-thawed Blastocyst Transfer with Different Qualities of Embryos: A Large Matched-cohort Study

OBJECTIVE

This study aimed to determine whether the day of blastocyst expansion affects pregnancy outcomes in frozen-thawed blastocyst transfer (FBT) cycles.

METHODS

A retrospective match-cohort study was conducted. Patients who underwent blastocyst transfer in frozen-thawed cycles at day 5 or 6 were matched for potential confounding factors. A total of 2207 matched pairs of FBT cycles were included from January 2016 to December 2019 in our Reproductive Medicine Center.

RESULTS

The clinical pregnancy rate (CPR) and live birth rate (LBR) were significantly increased in day 5 blastocyst transfers when compared to day 6 blastocyst transfers, in terms of the same embryo quality. For FBT cycles with good-quality embryo, the CPR at day 5 and 6 was 61.30% and 57.56%, respectively (P=0.045), and the LBR was 44.79% and 36.16%, respectively (P<0.001). For FBT cycles with poor-quality embryo, the CPR at day 5 and 6 was 48.61% and 40.89%, respectively (P=0.006), and the LBR was 31.71% and 25.74%, respectively (P=0.019). The CPR for FBT cycles with good-quality embryo was statistically higher at day 6 than that at day 5 with poor-quality embryo transferred (57.56% vs. 48.61%, P=0.001). Maternal age, anti-Müllerian hormone (AMH), endometrial thickness, embryo quality, and the day of blastocyst expansion were independently correlated with the CPR and LBR. The FBT cycles at day 5 had significantly higher CPR (adjusted odds ratio [OR]=1.246, 95% confidence intervals [CI]: 1.097-1.415, P=0.001) and LBR (adjusted OR=1.435, 95% CI: 1.258-1.637, P<0.001) than those at day 6.

CONCLUSION

The embryo quality is the primary indicator for FBT cycles. Day 5 blastocysts should be preferred when the quality of embryo at day 5 is the same as that at day 6.

Effects of sequential cleavage and blastocyst embryo transfer on pregnancy outcomes in patients with poor ovarian response

The management of patients with poor ovarian response (POR) remains a major challenge for fertility specialists in in vitro fertilization-embryo transfer (IVF-ET). In this retrospective cohort study, we aimed to evaluate the clinical effect of sequential transfer on pregnancy outcomes in patients with POR. A total of 3579 POR patients who underwent the first frozen embryo transfer (FET) cycle were enrolled from January 2018 to April 2021. The patients were divided into three groups according to the embryo transfer (ET) strategy adopted: a study group that included POR patients in whom a cleavage-stage embryo (day 3) and a blastocyst (day 5/6) were transferred (sequential transfer group), and two control groups in whom two cleavage-stage embryos (D3-dET group) or two blastocysts (D5/6-dET group) were transferred. The study group was matched with the control groups at a ratio of 1:4 by propensity score matching (PSM). The main pregnancy outcomes measured were the live birth rate and multiple pregnancy rate. After PSM, the live birth rate in the sequential transfer group was significantly higher than that in the D3-dET group (44.2% vs. 34.3%, P = 0.019), and was similar to that in the D5/6-dET group (44.2% vs. 45.3%; P = 0.90). In addition, there was no increase in the risk of multiple pregnancy among POR patients undergoing sequential transfer compared with both D3-dET (26.7% vs. 25.6%, P = 0.85) and D5/6-dET (26.7% vs. 28.4%, P = 0.97) groups. These findings imply that sequential transfer is an effective option for POR patients and could be utilized after careful consideration.

Obstetric and Perinatal Outcomes of Singleton Births Following Single- vs Double-Embryo Transfer in Sweden

Importance

Pregnancies resulting from assisted reproductive technology are associated with an increased risk of adverse perinatal outcomes compared with those following natural conception. Previous studies have shown an association of pregnancies resulting from transfer of multiple embryos with these negative findings.

Objective

To determine the risk for adverse outcomes in singletons conceived through assisted reproduction using double-embryo transfer (DET) vs single-embryo transfer (SET).

Design, Setting, and Participants

This cohort study used data from women who achieved singleton deliveries after SET or DET in Sweden between 2007 and 2017 as recorded in the National Quality Registry for Assisted Reproduction. All embryo transfers, at cleavage or blastocyst stage, replaced in fresh or frozen treatment cycles were included. Data on obstetric and neonatal outcomes were retrieved by linkage to the National Medical Birth Register. Naturally conceived singletons were included as a reference group. Data were analyzed between September 2021 and August 2022.

Exposures

Double-embryo transfer leading to singleton birth.

Main Outcomes and Measures

Relative risk ratios or odds ratios (ORs) and absolute risk differences (ARDs) in percentage points with 95% CIs were calculated for obstetric and perinatal outcomes in singleton births conceived using DET vs SET.

Results

Among 1 115 863 singleton births, 30 713 singletons were born after SET and 5123 after DET. A higher risk of neonatal death was found in singletons after DET vs SET (OR, 2.67 [95% CI, 1.28-5.55]; ARD, 0.2 percentage points [95% CI, 0.0-0.4 percentage points]). In frozen embryo transfers, DET was associated with a higher risk of low birth weight (OR, 1.64 [95% CI, 1.19-2.25]; ARD, 2.0 percentage points [95% CI, 0.5-3.5 percentage points]). Among blastocyst transfers, DET was associated with very preterm birth (relative risk ratio, 2.64 [95% CI, 1.50-4.63]; ARD, 1.8 percentage points [95% CI, 0.3-3.4 percentage points]) and low birth weight (OR, 1.83 [95% CI, 1.29-2.60]; ARD, 3.2 percentage points [95% CI, 0.9-5.5 percentage points]).

Conclusions and Relevance

These results indicate a higher risk of adverse outcomes following DET, even when the result is a singleton birth, vs singletons born after SET. Adverse outcomes were mainly observed in singletons following DET using frozen embryos and blastocysts.

Comparison of frozen-thawed embryo transfer strategies for the treatment of infertility in young women: a retrospective study

Objective

To investigate transfer strategies in the frozen-thawed embryo transfer (FET) cycle.

Methods

The clinical data of 1,652 FET patients were divided into five groups according to the number and quality of the transferred blastocyst: high-quality single blastocyst group (group A, n = 558), high-quality plus poor-quality double blastocyst group (group B, n = 435), poor-quality double blastocyst group (group C, n = 241), high-quality double blastocyst group (group D, n = 298), and poor-quality single blastocyst group (group E, n = 120). Inter-group comparison analyses of primary conditions, pregnancy outcomes and neonatal outcomes were then performed.

Results

Group A had the highest embryo implantation rate (67.38%), significantly different from the implantation rates of the other four groups. The gemellary pregnancy rate (1.60%), preterm birth rate (5.58%), neonatal birth weight (3,350g [3,000g, 3,650g]), neonatal birth age (39.57 weeks [38.71, 40.34]), and incidence of low birth weight (7.02%) in group A were different from those in groups B, C, and D, but did not significantly differ from those in group E. Moreover, the proportions of male infants born in groups A (56.86%) and D (59.41%) were significantly higher than those in the other three groups. Double blastocyst transfer (0.528, 95% CI [0.410-0.680], P < 0.001) and high-quality blastocyst transfer (0.609, 95% CI [0.453-0.820], P = 0.001) were found to be protective factors for live birth. In addition, double blastocyst transfer was also the largest risk factor for pregnancy complications (3.120, 95% CI [2.323-4.190], P < 0.001) and neonatal complications (2.230, 95% CI [1.515-3.280], P < 0.001), especially for gemellary pregnancy (59.933, 95% CI [27.298-131.58], P < 0.001) and preterm birth (3.840, 95% CI [2.272-6.489], P < 0.001). Based on the ROC curves, a double blastocyst transfer could predict gemellary pregnancy reliably with a high area under the curve (AUC = 78.53%). Additionally, a double blastocyst transfer could effectively predict a high risk of pregnancy complications (AUC = 65.90%), neonatal complications (AUC = 64.80%) and preterm birth (AUC = 66.20%).

Conclusion

The live birth rate of frozen-thawed high-quality single blastocyst transfer is lower than that of double high-quality blastocyst transfer, which can significantly increase the embryo implantation rate. High-quality single blastocyst transfer also significantly lowers the risk of gemellary pregnancy, preterm birth, and low birth weight, and can significantly improve maternal and infant outcomes. After weighing the pros and cons of live birth with pregnancy and neonatal complications, the authors believe that high-quality single blastocyst transfer is the optimal FET strategy for young women and is worthy of further clinical application. Despite this recommendation, high-quality single blastocyst transfer can increase the risk of monozygotic twins, as well as significantly increase the proportion of male infants born.

The Application of Artificial Intelligence in Predicting Embryo Transfer Outcome of Recurrent Implantation Failure

Background: Recurrent implantation failure (RIF) refers to that infertile patients have undergone multiple in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles and transferred multiple embryos without embryo implantation or clinical pregnancy. Due to the lack of clear evidence-based medical guidelines for the number of embryos to be transferred in RIF patients, how to obtain the highest single cycle pregnancy success rate with as few embryos transferred as possible while avoiding multiple pregnancy as much as possible, that is, how to balance the pregnancy success rate and multiple pregnancy rate, is a great challenge for clinicians and RIF patients. We urgently need an effective and reliable assisted decision-making method to help clinicians find this balance, and an artificial intelligence (AI) system will provide an efficient solution.

Design and Methods: In this research, we filtered out the RIF data set (n = 45,921) from the Human Fertilisation and Embryology Authority (HFEA) database from 2005 to 2016. The data set was divided into two groups according to the number of embryos transferred, Group A and B. Group A included 34,175 cycles with two embryos transferred, while Group B included 11,746 cycles with only one embryo transferred, each containing 44 features and a prediction label (pregnancy). Four machine learning algorithms (RF, GBDT, AdaBoost, and MLP) were used to train Group A and Group B data set respectively and 10-folder cross validation method was used to validate the models.

Results: The results revealed that the AdaBoost model of Group A obtained the best performance, while the GBDT model in Group B was proved to be the best model. Both models had been proved to provide accurate prediction of transfer outcome.

Conclusion: Our research provided a new approach for targeted and personalized treatment of RIF patients to help them achieve efficient and reliable pregnancy. And an AI-assisted decision-making system will be designed to help clinicians and RIF patients develop personalized transfer strategies, which not only guarantees efficient and reliable pregnancy, but also avoids the risk of multiple pregnancy as much as possible.

Risk factors for twin pregnancy in women undergoing double cleavage embryo transfer

Background

Two or more embryo transfers have been used to increase the success rate of live birth in traditional in vitro fertilization (IVF) strategy at the expense of increased risks of multiple pregnancy and adverse perinatal outcomes. The decision regarding the elective single embryo transfer or double embryo transfer remains inconclusive. The aim of this study was to investigate the risk factors for twin pregnancy in IVF.

Methods

Participants who underwent their first fresh IVF cycle where two cleavage stage embryos were transferred in Women’s Hospital of Zhejiang University between January 2010 and December 2018 were included in this retrospective cohort study. The primary outcome was twin delivery. Secondary outcomes included preterm birth and low birth weight

Results

Fifteen thousand four hundred fifty-nine women were available for final analysis, in which 1511 women resulted in twin delivery and 4788 women had singleton delivery. Female age over 35 was associated with reduced rates of twin pregnancy compared with female age at or less than 35 (9.5% vs 25.1%, aRR = 0.38 (0.27. 0.55)). Poor-type endometrium was associated with reduced rates of twin pregnancy (19.2% vs 27.5%, aRR = 0.75 (0.58. 0.96)). Two good-quality embryos for transfer was associated with significantly higher rates of twin pregnancy compared with one good-quality or none good-quality embryo (26% vs 12.8% vs 9.3%, aRR = 0.56 (0.45. 0.70), aRR = 0.44(0.26. 0.74)). Female age over 35 and none or one good-quality embryo for transfer were associated with reduced rate of low birth weight and preterm birth.

Conclusion

Women with age over 35, poor-type endometrium, one good-quality embryo or none good-quality embryo were associated with reduced rate for twin pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04606-1.