Letrozole Versus Hormonal Preparation in Frozen Cycles of PCOS Patients.

One of the indications of freezing is to reduce the risk of ovarian hyperstimulation syndrome particularly in polycystic ovarian disease (PCOS) women. Very few RCTs addressed the issue of optimizing the endometrium for a frozen cycle. Interestingly, Letrozole for ovarian stimulation showed significantly better reproductive outcome when compared with hormone replacement therapy (HRT) cycle. In addition, HRT cycle has been associated with higher miscarriage rate when compared with natural cycle frozen embryo transfer. Nevertheless, there is not yet a well-designed prospective randomized study comparing letrozole and HRT in PCOS women undergoing frozen embryo transfer.