Pregnancy Outcomes After Different Cycle Regimens for Frozen-Thawed Embryo Transfer: A Retrospective Study Using Propensity Score Matching

Abstract

Background: Nowadays, the choice of frozen embryo transfer (FET) regimens is mainly guided by personal convenience. Clinicians prefer the predictability and reliability of artificial cycle (AC) FET and have extended its usage to general in vitro fertilization population. More recent primary studies are beginning to challenge the comparability of AC-FET and suggest reduced clinical pregnancy rate and live birth rate (LBR) compared with those in modified natural cycle (mNC) FET (ovulation triggered by human chorionic gonadotrophin) and stimulated cycle (SC) FET. Objective: To assess the pregnancy outcomes within matched mNC-FET, SC-FET, and AC-FET cycles by using propensity score matching (PSM) in a larger cohort. Methods: A total of 16,946 women who underwent their first autologous FET cycle between July 2014 and July 2017 were evaluated. PSM, using the nearest neighbor matching, were established to adjust the baseline features within the three protocols in proportion of 1:1 (mNC-FET vs. SC-FET, mNC-FET vs. AC-FET, SC-FET vs. AC-FET). Furthermore, there were 3,567, 2,917, and 3,964 cycles compared between matched mNC-FET and SC-FET, mNC-FET and AC-FET, and SC-FET and AC-FET after the PSM, respectively. Results: LBR was significant lower in the AC-FET group than that in the mNC-FET (40.0 vs. 43.3%) and SC-FET groups (40.9 vs. 46.5%). The adjusted odds ratios (95% CIs) were 1.11 (1.00, 1.24) for mNC/AC (P = 0.044) and 0.84 (0.76, 0.92) for AC/SC (P < 0.001), which indicated that the AC-FET group was associated with lowest LBR. The LBR was comparable between matched mNC-FET and SC-FET after adjusting for endometrial thickness. Moreover, a lower clinical pregnancy rate and a higher risk of early pregnancy loss were discovered in AC-FET cycles compared with those in SC-FET. Conclusion: In view of our data, AC used for scheduling FET was associated with lower LBR compared with SC and modified natural cycle. This interpretation requires Wang et al. Abnormal Implantation in AC future verification from well-designed prospective multicenter randomized clinical trials, although the comparisons in our study were conducted in the homogenous population after the PSM.

Pregnancy Outcomes After Frozen-Thawed Embryo Transfer in the Absence of a Corpus Luteum

“…However, more recent studies suggest better outcomes with regards to clinical (19,(33)(34)(35)(36)(37), ongoing (19,33,(38)(39)(40), and live birth (18,19,33,34,(36)(37)(38)(40)(41)(42)(43) rates in (modified) natural or stimulated FET cycles compared to cycles performed in an artificial setting. Nevertheless, these data are from different populations and quality and mainly from retrospective observational studies which prompts caution when drawing conclusions for clinical practice.…”

Hormone replacement cycles are associated with a higher risk of hypertensive disorders: Retrospective cohort study in singleton and twin pregnancies

“…No differences between these cycle regimens have been demonstrated in terms of pregnancy rates 6 . However, serious maternal and neonatal complications associated with HRC‐FET were first described in data from Sweden, 8 Japan 9 and China 10 . A doubled to tripled risk of pre‐eclampsia, 8–10 a six‐fold risk of placenta accreta 9,11 and doubled risk of caesarean section 11 occurred in HRC‐FET compared with NC‐FET.…”

“…However, serious maternal and neonatal complications associated with HRC‐FET were first described in data from Sweden, 8 Japan 9 and China 10 . A doubled to tripled risk of pre‐eclampsia, 8–10 a six‐fold risk of placenta accreta 9,11 and doubled risk of caesarean section 11 occurred in HRC‐FET compared with NC‐FET. A recent systematic review and meta‐analysis revealed the lowest risks of hypertensive disorders in pregnancy (relative risk [RR] 0.61, 95% CI 0.50–0.73) and pre‐eclampsia (RR 0.47, 95% CI 0.42–0.53) in NC‐FET compared with HRC‐FET 12 .…”

Comparison of Stimulated Cycles with Low Dose r-FSH versus Hormone Replacement Cycles for Endometrial Preparation Prior to Frozen-Thawed Embryo Transfer in Young Women with Polycystic Ovarian Syndrome: A Single-Center Retrospective Cohort Study from China

“… 11 , 12 There are different ways for endometrial preparation, ranging from natural cycle (NC-FET) to stimulated cycle (STC-FET), or hormone replacement cycle (HRC-FET). 13 However, elucidating which is the best option remains to be determined. 14 The NC cycle is suitable for patients with regular menstrual periods.…”