The effect of the starting date of controlled ovarian stimulation with clomiphene citrate on the endometrial thickness

Abstract

This study was undertaken to determine whether the starting date of controlled ovarian stimulation with clomiphene citrate has an effect on endometrial thickness. Case control clinical study. Endometrial thickness on day of hCG administration was measured in (n= 14) patients during four consecutive cycles: natural cycle, controlled ovarian stimulation with clomiphene citrate 100 mg on days 3–7 of the menstrual cycle. Patients who developed a thin endometrial lining (<6 mm), in the subsequent cycle, clomiphene citrate 100 mg was administered on days 5–9 of the menstrual cycle. Endometrial thickness was compared to a controlled ovarian stimulation cycle with gonadotropins. Patients age, infertility diagnosis, BMI, basal cohort of follicles, maximum estradiol level on day of hCG administration, number of follicles > 16 mm, endometrial thickness were recorded. Statistical analysis were done using Welch’s Anova or Kroskal-Wallis test considering statistical significant a p-value <0.05. Patients mean age 32.1 ± 4.2, infertility diagnosis: unexplained (n=4), anovulation (n=3), male (n=6), tubal factor (n=3). Patients mean BMI 25.3 ± 4.2. There were no statistical significant differences in mean Estradiol levels and endometrial thickness on day 3 of the menstrual cycle between the cycles. There was a statistical significant difference in endometrial thickness on day of hCG administration between the natural cycle 7.9 ± 1.1.mm, and the controlled ovarian stimulation with clomiphene citrate. Starting on day 3 of the menstrual cycle 5.0 ±0.8 mm compared to 5.8± 1.4 mm when clomiphene citrate was administered starting day 5 of the menstrual cycle. There was no statistical difference in endometrial thickness between the two clomiphene starting day protocols. There was a difference in number of patients who developed an endometrial thickness < 6 mm on the day of hCG administration when clomiphene citrate was administered staring day 3 (10/12–83%) compared to (7/14–50%) when clomiphene citrate was administered starting on day 5 of the menstrual cycle. Endometrial thickness <6 mm on day of hCG administration was not detected during natural cycle or gonadotropin administration. There is an increase incidence of negative effect on endometrial thickness when clomiphene citrate was administered starting on day 3 of the menstrual cycle. Starting clomiphene citrate on day 5 of the menstrual cycle improves the endometrial thickness and the gonadotropin administration does not have any negative effect on the endometrial thickness.