Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation

In this multicenter, randomized trial published in NEJM, 900 couples with unexplained infertility were enrolled to test the standard therapy of gonadotropin or clomiphene citrate for women with unexplained infertility against ovarian stimulation with letrozole to reduce multiple gestations while maintaining live birth rates. The primary outcome was the rate of multiple gestations among women with clinical pregnancies, and we found that in women with unexplained infertility, ovarian stimulation with letrozole resulted in a significantly lower frequency of multiple gestation but also a lower frequency of live birth, as compared with gonadotropin but not as compared with clomiphene.