Application of letrozole inhibitors in polycystic ovary syndrome receiving gonadotropin-releasing hormone antagonist protocols

Objective To investigate the effectiveness and safety of letrozole combined with gonadotropin-releasing hormone antagonist (GnRH-A) protocol in patients with polycystic ovary syndrome (PCOS) and receiving in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). Methods We retrospectively reviewed the medical documents of PCOS patients receiving IVF/ICSI in the Reproductive Medicine Center of Peking University People’s Hospital from January 2014 to December 2016. Totally 132 patients were included and divided into two groups. Group A (n=50) received letrozole combined with GnRH-A protocol for controlled ovarian hyperstimulation (COH). Group B (n=82) received GnRH-A protocol. The clinical characteristics and pregnancy outcomes of the two groups were analyzed and compared. Results There were no significant differences in age, duration of infertility, body mass index (BMI) of the two groups (P>0.05). The initial and total dosage of gonadotropin (Gn) used and the duration of COH were significantly lower and shorter in group A than in group B (P 0.05). We found no significant differences in the number of retrieved oocytes, MII oocytes and high-quality embryos between the two groups (P>0.05). There were no differences in the prevalence of ovarian hyperstimulation syndrome (OHSS) (0% vs. 1.22%), fresh embryo transplantation rate (46.80% vs. 42.30%), implantation rate (42.42% vs. 46.42%) and cycle cancellation rate (6.00% vs. 4.87%) between group A and group B (P>0.05). The clinical pregnancy rate, the live birth rate and the spontaneous abortion rate per embryo transfer were 50.00% (11/22), 50.00% (11/22) and 0% (0/11) in group A, respectively, showing no statistical difference with that of group B [51.52% (17/33), 42.42% (14/33), 5.88% (1/17), respectively]. Conclusion For PCOS patients receiving assisted reproductive technology (ART), letrozole combined with GnRH-A protocol can significantly reduce the total dosage of Gn used, COH duration and the risk of OHSS without reducing the clinical pregnancy rate per cycle and the live birth rate. Key words: Letrozole; Polycystic ovary syndrome; Gonadotropin-releasing hormone antagonist; Controlled ovarian hyperstimulation