Letrozole may increase gestational diabetes risk during Frozen Embryo Transfer in Women With PCOS

A recent study published in Obstetrics & Gynecology by Yuan et al. and colleagues has concluded that Letrozole application & artificial cycle for endometrial preparation in PCOS patients undergoing FET show similar pregnancy outcomes but differ in perinatal results. There are similarities reported between live birth rates and secondary outcomes. The use of Letrozole was associated with a higher risk of GDM. The artificial cycle group had higher singleton birth weight.

In this randomized controlled trial, researchers from the Reproductive Medicine Center of the First Affiliated Hospital of SUN Yat-sen University compared live-birth rates between letrozole application and artificial cycle for endometrium preparation during frozen embryo transfer (FET) cycle among PCOS women.

The primary outcome was the live birth rate per embryo transfer. Secondary outcomes included pregnancy-related outcomes, perinatal outcomes, and maternal complication rates. Assuming α=0.05 and 80% power, a sample size of 186 patients per group was required to demonstrate a difference of 15% in live birth rate: 205 patients were assigned to each group.

Key results from the study are:

• From 2018-2021, four hundred twenty patients were enrolled.
• Two hundred ten patients were assigned to the letrozole application group and 210 to the artificial cycle group.
• There was no difference in the live birth rate (42.4% vs 42.9%).
• Secondary outcomes had no similarities. The clinical pregnancy, implantation and miscarriage rates were 51.4% vs 56.2%, 51.8% vs 55.8% and 8.6% vs 11.0%, respectively.
• Singleton's birth weight was higher in the artificial cycle group (3,108±56 g vs 3,301±58).
• The Letrozole application group had a higher incidence of gestational diabetes mellitus. (14.6% vs 5.6%).
• There was no difference in maternal complications.

There was no significant disparity in pregnancy outcomes between the Letrozole application and Artificial Cycle for endometrial preparation in PCOS women who underwent Frozen Embryo Transfer. Notably, the risk of Gestational Diabetes Mellitus was higher in the Letrozole application group, and the singleton birth weight was lower in the Artificial Cycle group.

Reference:

Yuan Y et al. Letrozole During Frozen Embryo Transfer in Women With Polycystic Ovarian Syndrome: A Randomized Controlled Trial. Obstet Gynecol. 2023 Nov 1;142(5):1087-1095.