Letrozole Compared With Clomiphene Citrate for Unexplained Infertility A Systematic Review and Meta-analysis.复制标题

来曲唑与枸橼酸氯米芬治疗不明原因不孕症的比较: 系统回顾和荟萃分析。

Oral ovarian stimulation agents such as clomiphene citrate, a selective estrogen receptor modulator, and letrozole, an aromatase inhibitor, are effective, have fewer adverse side effects, and lower cost than injectable gonadotropins. After a basic infertility workup, oral ovulation induction is often the first step in treatment before referral to reproductive endocrinology. Clomiphene citrate is the standard first line agent for ovarian stimulation. However, studies have shown that clomiphene citrate may alter surrogate parameters of uterine receptivity and cervical mucus, which may explain why pregnancy rates are often lower than expected from observed ovulation rates. Letrozole lacks the antiestrogenic effects of clomiphene citrate on the endometrium and has a shorter half-life, contributing to reduced side effects. Additionally, use of aromatase inhibitors appears to improve endometrial thickness compared to clomiphene citrate and may be less likely to result in multiple gestations. Letrozole use also resulted in higher live birth rates compared to clomiphene citrate in patients with PCOS.

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