This study evaluated which endometrial preparation protocol in frozen embryo transfer (FET) cycles provides the best results for polycystic ovarian syndrome (PCOS) patients and the general population. This retrospective study of 634 FET cycles was conducted 2016–2018. Cycles were divided into Group A: Artificial endometrial preparations for FET (aFET; n = 348), Group B: Ovulatory cycle (n = 286) to compare two methods of endometrial preparation for FET. Artificial endometrial preparation with exogenous estrogen and progesterone versus natural ovulation cycles, modified natural cycles using hCG for the final triggering and letrozole-induced ovulation with hCG. Anovulatory patients were analyzed separately. Anovulatory PCOS patients had significantly higher pregnancy rates with letrozole treatment compared with aFET cycles (44% vs. 22.5%; p = 0.044). For the entire cohort, ovulatory cycles and aFET were similar in terms of patient characteristics, demographics, infertility causes, treatment protocols and number of embryos transferred. Although the mean ESHRE score of the transferred embryos was higher in the aFET group, we found higher clinical pregnancy rate in the ovulatory cycle FET (41.3% vs. 27.3%, p < 0.0001). A better pregnancy rate was found after ovulatory cycle FET. In the ovulatory cycles, the outcome of letrozole-induced and non-induced cycles were comparable. PCOS patients, as well as the general population, may benefit from ovulation induced FET cycles, with significantly better outcomes in FET in ovulatory cycles.

This prospective, observational study investigated the incidence of irregular cleavage (IRC) among human embryos and its influence on IVF treatment outcomes. It included 1001 women who underwent 1976 assisted reproduction treatments during 2016–2021 in a single IVF clinic. Embryo morphokinetics were analyzed and evaluated for the association between IRC and women’s characteristics, treatment characteristics, and pregnancy outcomes. The incidence of IRC was 17.5% (1689/9632 embryos). Of these, 85% of the embryos had one IRC, 15% had multiple IRC and 35% of IRC events occurred during the embryo’s first cell cycle. IRC embryos were found to correlate with male factor (p = 0.01) and higher ICSI rate (p = 0.01). Age, BMI, parity, basal FSH level, stimulation protocol, and number of retrieved oocytes did not differ between groups. Embryos with early IRC or more than one IRC had lower blastulation rates (p = 0.01 for each). Fresh cycles with IRC embryos had a lower clinical pregnancy rate (p = 0.01) and embryos with early IRC had a lower live birth rate (p = 0.04) compared to embryos without IRC. Frozen transfer cycles of blastocyst embryos, with or without IRC, had comparable results. In conclusion, the number of abnormal cleavage events and their timing are important factors in the prognosis of the developing human embryo.

Increased progesterone level during follicular phase seemed to be associated with decreased pregnancy rate. A prospective cohort study, 1.1.2012 - 31.8.13. The Progesterone (P) and Progesterone/Estrogen (P/E2) level on ovulation induction day were compared between the protocols and the different gonadotropins used. Roc analysis was calculated to determine the cutoff of P/E2 to predict delivery rates. P/E2 ratio was calculated as PX1000/e2 level. One hundred thirty-nine patients were enrolled to the study. No difference in the P level at hCG stimulation day between different protocols, however, E2 and P/E2 ratio were significantly lower in the long protocol compare with antagonist protocol 1757.7 ± 923.2 vs. 1342.9 ± 1223; P = 0.003 and 0.48 ± 0.31 vs. 0.83 ± 0.87; P = 0.038). The endometrium was significantly thicker in the long group compare with short and antagonist. Significantly more top-quality embryos (TOP) were achieved in the antagonist group. Comparable results between the types of gonadotropins used in regards with cycle characteristics and pregnancy and delivery rates. The P/E2 ratio which can predict live birth rate was found to be 0.45, AUC = 0.632, p = 0.02 and 95 % CI 0.525–0.738 and a significantly higher pregnancy and delivery rates at a P/E2 bellow 0.45. Endometrial receptivity is determined by the complex interactions of E2 and P.

This retrospective cohort study examined the effect of maternal BMI on embryo morphokinetics using a time-lapse incubator (TLI) and evaluated the effect on outcomes of frozen embryo transfer (FET) cycles. The study included 641 women who underwent FET of a total of 2553 embryos from January 2017 to August 2019. The women were divided into four groups according to BMI: underweight (<18.5 kg/m²), normal weight (18.5–24.99 kg/m²), overweight (25.0–29.99 kg/m²), and obese (≥30 kg/m²). Embryos were transferred on day 3 or 5, and their development was monitored using a TLI. We found that oocytes from obese patients were slower in the extraction of the second polar body (tPB2) after fertilization and the two pronucleus stage appeared later compared to normal-weight women. The time to fading of the pronucleus (tPNf), t2, and t4 were comparable between the four groups. Oocytes from underweight and overweight women had significantly faster cleavage at t3 and t5–t8 compared to normal weight. We did not find any significant difference in pregnancy rate, clinical pregnancy rate, or miscarriage rate among groups. In conclusion, embryos from normal-weight patients had slower cleavage rates compared to obese patients, while embryo quality was similar between BMI groups. The cycle outcomes demonstrated comparable pregnancy rates among the BMI groups.

This prospective, case-control study evaluated the impact of obesity on oocyte quality based on mtDNA expression in cumulus cells (CC), and on bone morphogenetic protein 15 (BMP-15) and heparan sulfate proteoglycan 2 (HSPG2) in follicular fluid (FF). It included women 18 to <40 years of age, divided according to BMI < 24.9 (Group 1, n = 28) and BMI > 25 (Group 2, n = 22). Demographics, treatment, and pregnancy outcomes were compared. The mtDNA in CC, BMP-15, HSPG2, the lipid profile, the hormonal profile, and C-reactive protein were evaluated in FF and in blood samples. The BMP-15 levels in FF and the mitochondrial DNA in CC were higher in Group 1 (38.8 ± 32.5 vs. 14.3 ± 10.8 ng/mL; p = 0.001 and 1.10 ± 0.3 vs. 0.87 ± 0.18-fold change; p = 0.016, respectively) than in Group 2. High-density lipoprotein levels in blood and FF were higher in Group 1 (62 ± 18 vs. 50 ± 12 mg/dL; p = 0.015 and 34 ± 26 vs. 20.9 ± 7.2 mg/dL; p = 0.05, respectively). Group 2 had higher blood C-reactive protein (7.1 ± 5.4 vs. 3.4 ± 4.3 mg/L; p = 0.015), FF (5.2 ± 3.8 vs. 1.5 ± 1.6 mg/L; p = 0.002) and low-density lipoprotein levels (91 ± 27 vs. 71 ± 22 mg/dL; p = 0.008) vs. Group 1. Group 1 demonstrated a trend toward a better clinical pregnancy rate (47.8% vs. 28.6%: p = 0.31) and frozen embryo transfer rate (69.2% vs. 53.8; p = 0.69). Higher BMI resulted in lower BMP-15 levels and reduced mtDNA expression, which reflect decreased oocyte quality in overweight women.