A randomized controlled trial with addition of letrozole as an adjunct to FSH in high responders in stimulated IVF cycles show negative impact of ovarian stimulation on the endomterium

Abstract

Can letrozole reduces the incidence of premature progesterone rises late follicular phase, and thus impact positively on endometrial receptivity to high responders in stimulated in vitro fertilization (IVF) cycles? A randomized parallel controlled trial This randomized parallel controlled trial was conducted in from the Hospital from October 2015 to August 2016.Altogether 133 women undergoing IVF treatment were randomized into two groups using computer-generated randomization plan, to one of the following two treatment regimens: A standard GnRH-a protocol and 100 IU-225IU recFSH were applied from stimulation day 1 and letrozole 2.5 mg/day from cycle day 5 to the day before hCG administration (Letrozole group, n=69) or none (control group, n=64).Standard luteal phase support with progesterone were provided. While estradiol levels were significantly lower in the letrozole group (P < 0.001), the progesterone levels (1.09±0.40,0.93±0.38)ng/ml and P/E2(0.74,0.30) (P < 0.05) on the day of hCG administration were increased in the letrozole group. RecFSH , the recovery rate of eggs, Fertilization rate, high-quality embryo rate,thickness of endometrium,were similar between the letrozole and control groups. Clinical pregnancy rate: 58.5%(31/53),72.9%(35/48) was lower in the letrozole group, although there was no statistical significance by T test( P=0.128 ). The results suggest that co-treatment with letrozole can not reduce the incidence of premature progesterone rise at the late follicular phase,thus show negative impact on endometrial receptivityin in stimulated IVF cycles.With no increase in clinical pregnancy rates compared with control group in high responders undergoing assisted reproductive technology.