Clomiphene citrate affects the receptivity of the uterine endometrium.

PurposeTo 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).MethodsFrom 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.ResultsPR 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 < 0.05).ConclusionsA lower PR was shown by the patients who underwent thawed ET in the HRC within 90 days after their last CC treatment, which shows that CC affects the receptivity of the uterine endometrium.