Freeze-all, for whom, when, and how

Does The Culture of Post-Thawed Cleavage-Stage Embryos to Blastocysts Improve Infertility Treatment Outcomes of Frozen-Thawed Embryo Transfer Cycles? A Randomised Clinical Trial

BACKGROUND

There is a definite shift in assisted reproductive centres from cleavage-stage embryo transfer (ET) to blastocyst transfer that is attributed to improvements in laboratory environments and advances in the development of embryo culture media. The aim of the study was to investigate the reproductive outcomes of thawed cleavage-stage ET versus blastocysts derived from an extended culture of these embryos.

MATERIALS AND METHODS

This open-label, randomised, parallel group clinical trial study enrolled 182 women aged ≤37 years who underwent frozen-thawed ET from November 2015 to June 2020 at Royan Institute Research Centre, Tehran, Iran. The women were randomly assigned to either the thawed cleavage ET group (n=110) or the post-thaw extended culture blastocysts group (n=72). The primary outcome measure was the clinical pregnancy rate. Secondary outcome measures were implantation rate, live birth rate (LBR), and miscarriage rate. A P<0.05 indicated statistical significance.

RESULTS

There were no significant differences between the two groups in terms of demographic characteristics. Both the mean numbers of embryos transferred and good quality embryos transferred were significantly lower in the postthaw extended culture blastocysts group compared to thawed cleavage-stage ET cycles. However, the post-thaw extended culture blastocysts group had higher clinical pregnancy (56.94 vs. 40.91%, P=0.034), implantation (34.43 vs. 19.84%, P=0.001) and live birth (49.3 vs. 33.63%, P=0.036) rates compared to the thawed cleavage-stage ET group. Miscarriage and multiple gestations rates were comparable between the groups.

CONCLUSION

These results allow us to take a position in favour of post-thaw extended culture blastocysts; thus, it is important to improve the post-thawing extended culture technique (registration number: NCT02681029).

Elevated Anti-Müllerian Hormone as a Prognostic Factor for Poor Outcomes of In Vitro Fertilization in Women with Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) tend to have elevated anti-Müllerian hormone (AMH) levels, which appear to correlate with disease severity and pregnancy outcomes. This was a retrospective observational study designed to assess the relationship between circulating AMH levels and in vitro fertilization (IVF) outcomes. The study involved 150 women with PCOS who underwent IVF treatments. The women's IVF cycles were allocated into three subgroups according to AMH levels: 'low' (AMH < 3.7 ng/mL; n = 49), 'middle' (AMH 3.7-7.4 ng/mL; n = 94), and 'high' (AMH > 7.4 ng/mL; n = 56). All pregnancy-related outcomes (positive beta human chorionic gonadotropin (βHCG), clinical pregnancy rate, live birth rate, and cumulative live birth rate) were greater in women's IVF cycles with 'low' AMH when compared to those with 'middle' or 'high' AMH (p < 0.05). AMH levels below 3.7 ng/mL were found to be associated with lower oocyte immaturity rate and better pregnancy outcomes, although baseline AMH was not shown to have any significant predictive power for live birth and cumulative live birth in the multivariable logistic regression analysis after adjusting for possible confounders nor in the ROC analyses. In summary, the current study lays the groundwork to validate high AMH levels as a poor prognostic factor for pregnancy outcomes after IVF in women with PCOS.

A comprehensive review and update on human fertility cryopreservation methods and tools

The broad conceptualization of fertility preservation and restoration has become already a major concern in the modern western world since a large number of individuals often face it in the everyday life. Driven by different health conditions and/or social reasons, a variety of patients currently rely on routinely and non-routinely applied assisted reproductive technologies, and mostly on the possibility to cryopreserve gametes and/or gonadal tissues for expanding their reproductive lifespan. This review embraces the data present in human-focused literature regarding the up-to-date methodologies and tools contemporarily applied in IVF laboratories' clinical setting of the oocyte, sperm, and embryo cryopreservation and explores the latest news and issues related to the optimization of methods used in ovarian and testicular tissue cryopreservation.

Comparison of Clinical Pregnancy Outcomes after Fresh and Frozen Embryo Transfer

Objectives. To analyze the clinical outcomes of the patients who underwent fresh or frozen embryo transfer, as well as the neonatal outcomes. Methods. We conducted a retrospective analysis of women who underwent in vitro fertilization with fresh and frozen embryo transfer from January 2019 to January 2021. All of the included embryo transfers resulted in live births at ≥28 weeks of gestation. All of the patients were divided into two groups according to the assisted reproductive technique that was used (fresh embryo transfer group ( $n=101$ ) and frozen embryo transfer group ( $n=125$ )). Both groups were divided into subgroups based on a maternal age of ≥35 years. Result(s). Between the two groups, only the cesarean section rate was higher in the frozen transfer group, while no differences were shown for other outcomes. There were significant differences in the gestational hypertension and postpartum hemorrhage rates based on the subgroup comparison. No significant differences were detected in the offspring. Conclusions. Comparing fresh and frozen embryo transfers did not reveal any significant superiority. Venerable age exerts an apparent influence on pregnancy complications. Frozen embryo transfer is not always the best choice.

Wisdom of Freezing All Valuable Embryos

Background: It is controversial whether that “Freeze-only” strategy is superior to Fresh embryo transfer in ART patients with normal ovarian response. There are two reasons supporting a “Freeze-only” strategy. One is that frozen-thawed embryos are transferred to a more physiologically receptive endometrium. While fresh embryos are transferred to a badly affected one because of controlled-ovarian stimulations, which cause the discordant development of the endometrium, when thawed-frozen embryos are transferred in a subsequent cycle the endometrium is not affected by high estrogen levels. The other reason is the big difference in cryopreservation and stimulation techniques.

Methods: We investigated the annual ART reports in Japan from 1992 to 2018, and our clinical outcomes of frozen-thawed embryo transfers and fresh embryo transfers from 2015 to 2019. This enabled the assessment of the survival rate of frozen blastocyst by Cryotop safety kit after thawing in four different clinics. We compared the outcomes of frozen embryo transfer (FroET) to fresh embryo transfer.

Results: The proportion of birth in Japan in the study interval found that FroET was responsible for 86.7% of births, compared to 13.3% of births resulting from fresh embryo transfers after IVF or intracytoplasmic sperm injection (ICSI). Clinical outcome of FroET in our clinic was significantly higher than that of fresh embryo transfer regardless of maternal age and number of collected oocytes. Average survival rate of frozen blastocyst by Cryotop safety kit after thawing in four clinics was over 95%.

Conclusions: We believe that “Freeze-only high-quality blastocysts” is superior to fresh embryo transfer in terms of clinical outcome, at least when compared to historical results.

Effects of different frozen embryo transfer regimens on abnormalities of fetal weight: a systematic review and meta-analysis

BACKGROUND

Reported increases in maternal and perinatal morbidity (including macrosomia, large for gestational age (LGA), cesarean section, hemorrhage and hypertensive disorders of pregnancy) following frozen embryo transfer (FET) cycles may be associated with the lack of a corpus luteum seen in programmed FET. Given the growing number of studies comparing outcomes between natural FET and programmed FET cycles, a meta-analysis would prove useful to detect the presence of abnormalities in fetal birth weight in patients undergoing natural and programmed FET cycles.

OBJECTIVE AND RATIONALE

The aim of this study was to provide a systematic review and meta-analysis of the effects of natural versus programmed methods of endometrial preparation for FET cycles on fetal weight and the risks of LGA and macrosomia.

SEARCH METHODS

A literature search using MEDLINE, SCOPUS, EMBASE and clinicaltrials.gov was conducted for published research comparing neonatal outcomes in natural FET and programmed FET cycles. Primary outcomes of interest were fetal weight, macrosomia and LGA. Studies were included if the following criteria were met: study contained cohorts of NFET and programmed FET with outcome data of birth weight, large for gestational data and/or macrosomia. The data are presented as average weight and odds ratio (OR) with 95% confidence interval (CI) with fixed- or random-effects meta-analysis between cohorts of NFET and programmed FET cycles. Bias was assessed using Newcastle-Ottawa quality assessment scale for the 14 included studies. Multiple subgroup analyses were performed to assess for effect of the true natural cycle (defined as no ovulation trigger medication use) and the day of embryo transfer on fetal weight parameters compared with programmed cycle FET.

OUTCOMES

A total of 879 studies were identified, with 15 meeting inclusion the criteria. The studies varied with respect to country of origin, definition of natural cycle FET and type of progesterone supplementation used. The included studies had similar gestational ages at the time of birth. Programmed FET cycles resulted in a higher fetal weight compared with natural FET cycles (mean difference 47.38 gp = 0.04). Programmed FET cycles were also at higher risk for macrosomia (OR 1.15, 95% CI 1.06-1.26) and LGA (OR 1.10, 95% CI 1.02-1.19) compared with natural FET cycles. Subgroup analyses demonstrated that programmed FET cycles resulted in a higher fetal weight compared with true natural FET (mean difference 62.18 gp = 0.0001) cycles. Cleavage stage embryo transfers had an increased risk of LGA (OR 1.27, 95% CI 1.00-1.62) and an increased risk of macrosomia (OR 1.25, 95% CI 1.08-1.44) in programmed FET cycles compared with natural FET cycles. Blastocyst transfer in programmed FET cycles resulted in no difference in risk of macrosomia but an increased risk of LGA (OR 1.13, 95% CI 1.06-1.21) compared with natural FET cycles.

WIDER IMPLICATIONS

Programmed endometrial preparation for FET cycles had a significant effect, causing increased fetal birth weight and increased risks of LGA and macrosomia. The numbers of studies in the subgroup analyses were too low to determine reliable results. Further prospective randomized trials are needed to determine whether the changes seen in the observational trials are indeed accurate.

Frozen-thawed embryo transfers: time to adopt a more "natural" approach?

The increasing use of frozen-thawed embryo transfer (FET) cycles has magnified the focus on endometrial preparation protocols in assisted reproduction. Emerging evidence suggests that natural cycle (NC) FETs are associated with improved outcomes, and that providers should consider increasing the utilization of NC FET at the expense of the currently favored artificial cycle (AC) FET as primary method for endometrial preparation.