Reproductive Techniques clinical trials

Does Letrozole Improve Pregnancy Outcome in Fresh Embryo Transfer IVF/ICSI Cycle?

Letrozole (Femara), is an aromatase inhibitor which is used in the treatment of hormonally-responsive breast cancer after surgery. It is a good target for selective inhibition because estrogen production is a terminal step in the biosynthetic sequence. Aromatase inhibitors are widely used as adjuvant endocrine therapy for postmenopausal women with breast cancer. They have been used off-label in the treatment of patients for increasing the number of ovarian follicles recruited in ovulatory women undergoing controlled ovarian hyperstimulation (COH). A shorter half-life (48 hours) which would predict a lower risk of teratogenicity. No direct antiestrogenic adverse effects on the endometrium, due to an absence of peripheral estrogen receptor blockade and the shorter half-life. For ovarian normal responders, instead of hCG (human chorionic gonadotropin), luteal support with exogenous progesterone supplementation is the standard protocol for patients who received fresh embryo transfer for avoiding the risk of OHSS. In other normal responders who have increasing risk of OHSS, the strategy of freezing all embryos are more favored. In previous studies, high estrogen-induced endometrial gland cells apoptosis might account for the defective endometrial receptivity in women with excessively high estrogen concentrations after ovarian hyperstimulation in IVF cycles. Since letrozole can reduce the serum level of estrogen due to its pharmacological properties, which in turn reduces the adverse effects of high estrogen on the endometrium and improve the endometrial receptivity for embryo implantation. The investigators anticipate that infertility patients will receive short-term oral administration of letrozole (2.5 mg/tab) once a day when estrogen is elevated in the late stage of ovulation stimulation when receiving ovulation stimulation for two to three days. And transvaginal ultrasound was performed every two to three days for growth of ovarian follicles until two days before oocyte retrieval. Observing whether taking the drug can improve the maturity of the oocyte, pregnancy rate, implantation rate, miscarriage rate, ongoing pregnancy rate and live birth rate of the fresh embryo transfer cycle.