OBJECTIVE

目的

Prior studies have shown higher pregnancy rates with FET following letrozole induced ovulation compared to those following natural ovulation. The aim of this study was to compare the pregnancy rates of natural (nat-FET) vs letrozole FET (let-FET) cycles in infertile women that were ovulatory.

既往研究提示来曲唑诱导排卵后，冷冻胚胎移植（FET）的妊娠率较自然排卵后的妊娠率更高。本研究的目的是比较在排卵正常的不孕女性中自然FET（nat-FET）与来曲唑FET（let-FET）周期的妊娠率。

MATERIALS AND METHODS

材料与方法

Retrospective cohort study performed in a university-affiliated fertility practice. All natural and letrozole FET cycles from 2015 to 2022 were included. Primary outcome was ongoing pregnancy rate (OPR). Secondary outcomes included rates of pregnancy (PR), biochemical loss, clinical pregnancy (CPR), clinical loss, and ectopic pregnancy. Continuous variables were compared using Student’s t-test. Categorical variables were compared with Chi-square or Fisher’s exact test. The outcomes were adjusted for BMI and age at embryo cryopreservation with multivariate logistic regression. A subgroup analysis including only PGT-A cycles was also performed.

 

回顾性队列研究在一家大学附属生育机构完成。纳入了所有2015年至2022年间自然周期及来曲唑诱导排卵冻融胚胎移植周期。首要结局是持续妊娠率（OPR），次要结局包括妊娠率（PR）、生化妊娠丢失、临床妊娠率（CPR），流产率以及异位妊娠率。连续变量应用T检验，分类变量应用卡方检验或Fisher正确概率检验。采用多变量逻辑回归对BMI和冻存胚胎时年龄进行调整。还进行了仅包括PGT-A周期的亚组分析。

RESULTS

结局

A total of 2466 FET cycles were included, with 1907 natural (77%) and 559 (23%) letrozole cycles. Patients who underwent letrozole FET had a higher BMI (27.7 vs 26.3 kg/m2, p < .01) and were younger at embryo transfer (35.5 vs 35.9 years, p = .047) and embryo cryopreservation (35.0 vs 35.4 years, p = .042). The rates of PGT-A (37 vs 35%, p = 0.25) were similar between groups. OPRs were similar between groups as well as the PR, CPR, biochemical loss rate, clinical pregnancy loss rate, and ectopic pregnancy rate (table 1). The pregnancy rates remained similar between groups after adjusting for BMI and age at embryo cryopreservation using multivariate logistic regression. Among the 867 FET cycles that utilized PGT-A, OPRs were similar between groups despite a higher clinical loss rate in the letrozole group (table 1). The other pregnancy rates were similar between groups. The results were unchanged after adjusting for BMI and age at embryo cryopreservation.

共计纳入2466周期，其中自然周期1907例（77%），LE诱导周期559例（23%）。应用来曲唑的冻融周期患者的BMI更高 (27.7 vs 26.3 kg/m2, p <0.01)，且胚胎移植（35.5岁vs 35.9岁, p＝0.047）及冻存时更年轻（35.0岁vs 35.4岁, p＝0.042）。PGT-A率在组间类似（37 vs 35%，p＝0.25）。持续妊娠率（OPRs）与临床妊娠率（PR）、妊娠率（CPR）及生化妊娠、临床妊娠丢失率以及异位妊娠率之间无显著差异。采用多变量逻辑回归经对BMI和冻存胚胎年龄校正后妊娠率无差异。应用PGT-A的867周期中，尽管来曲唑组有更高的临床妊娠丢失率，持续妊娠率（OPRs）相近。其他妊娠率组间亦类似。结果经由BMI及冻存胚胎时年龄校正后亦无改变。

CONCLUSIONS

结论

Among ovulatory women, the use of letrozole to stimulate ovulation was not associated with improved pregnancy rates.

排卵功能正常的女性中应用来曲唑诱导排卵并不能提高妊娠率。

IMPACT STATEMENT

影响陈述

This is the first study we are aware of that compared the pregnancy outcomes of natural FET to letrozole stimulated FET in women who are ovulatory. Our study suggests that letrozole might not improve pregnancy rates compared to natural FET cycles in ovulatory women.

这是我们所知首个针对可自发排卵女性应用来曲唑诱导排卵与自然冻融胚胎周期妊娠结局比较的研究。我们的研究提示在可自发排卵的女性中来曲唑的应用可能并不提高冻融胚胎周期妊娠率。

文章来源：

DOES STIMULATING OVULATION WITH LETROZOLE DURING FROZEN EMBRYO TRANSFER (FET) CYCLES IMPROVE PREGNANCY RATES IN OVULATORY WOMEN?Wai Cheung, Jessica Ka et al.Fertility and Sterility, Volume 120, Issue 4, e304