Ovulatory-Based FET Cycles May Achieve Higher Pregnancy Rates in the General Population and among Anovulatory Women

Abstract

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.

The effect of mildly stimulated cycle versus artificial cycle on pregnancy outcomes in overweight/obese women with PCOS prior to frozen embryo transfer: a retrospective cohort study

“…In addition, the authors mentioned that in their country, letrozole was primary prescribed to patients with unexplained infertility rather than PCOS patients. To corroborate the findings of Tatsumi et al, a more recent retrospective cohort study conducted in Israel concluded that ovulation induction using letrozole might induce normal ovulation and physiological FET, resulting in better pregnancy rates in FET treatments for PCOS patients [ 26 ]. A recent historical cohort analysis on women with PCOS found that ovarian stimulation (OS) protocol with low doses of HMG achieved a higher LBR than hormone replacement therapy (HRT) protocol accompanied by the poorest endometrial thickness [ 27 ].…”

Systematic review update and meta-analysis of randomized and non-randomized controlled trials of ovarian stimulation versus artificial cycle for endometrial preparation prior to frozen embryo transfer in women with polycystic ovary syndrome

“…1 . Based on sensitivity analysis, 1 study (Aslih 2021) [ 14 ] was found with publication bias (Supplementary Fig. 2 A).…”

“…A recent meta-analysis including 4 retrospective studies with 2933 women with PCOS published from 2013 to 2019, suggested that the pregnancy outcomes, including rates of live birth, ongoing pregnancy, clinical pregnancy, implantation and miscarriage rate were not significantly different between artificial and ovarian stimulation cycles [ 12 ]. After that, 1 RCT study [ 13 ] and 4 retrospective studies [ 14 – 17 ] on the topic have been published, suggesting the therapeutic effects might be different among various ovulation stimulation regimens. Which stimulation regimen superior to HRT has yet been analyzed in the previous review paper.…”

Increased risk of abortion after frozen-thawed embryo transfer in women with polycystic ovary syndrome phenotypes A and D

“…Moreover, we also observed that the rate for the presence of a corpus luteum (because of different endometrial preparation protocols for FET) in PCOS phenotypes A and D was significantly lower than that in controls, which might be another reason for the higher rate of abortion. In clinical practice, for PCOS women with OA, clinicians generally adopt a hormone replacement therapy (HRT) cycle to prepared the endometrium for FET 29 . Recently, Xu et al 30 noticed that HRT cycles were related to a higher abortion rate, which is consistent with the results of a prior study 31 .…”