Clomiphene citrate affects the receptivity of the uterine endometrium

Purpose To investigate whether clomiphene citrate (CC) affects uterine receptivity or not, we evaluated pregnancy rates (PR) during the hormone replacement cycle (HRC) according to the period between the last day of CC administration and the day of embryo transfer (ET). Methods From March 2008 through March 2010, a total of 378 treatment cycles among 378 patients who received CC and had to avoid fresh ET due to a thin uterine endometrium were recruited. All patients underwent thawed ET using HRC. PRs were evaluated according to the period between the last CC treatment and the day of ET. Results PR for the groups in which the period between the last CC treatment and the day of ET increased to more than 91 days were significantly higher than that for group in which the period was less than 90 days ( p