Melatonin treatment results in progression of endometrial thickness in infertile women in IUI cycle

Background Infertility is a disease of the reproductive system, characterized by failure to establish a clinical pregnancy after 12 months of regular and unprotected sexual intercourse. This study was conducted with the aim of investigating the effect of melatonin on the thickness of the endometrium of infertile patients undergoing intrauterine insemination (IUI). Materials and methods This randomized, double-blind, placebo-controlled clinical trial was conducted in Shahid Jalil Infertility Clinic. 94 infertile patients 18–42 years of age undergoing IUI were randomly divided to a daily dose of 6 mg of melatonin or placebo for a 4-week period. Endometrial thickness was measured by transvaginal ultrasound on days 1, 11 and 14 for each patient. Also, the subjects' basic characteristics, including employment status, smoking, pregnancy rate, abortion rate, and live birth rate were recorded. Results The thickness of the endometrium in the group treated with melatonin was significantly different compared to the control group (P < 0.05). In addition, the clinical pregnancy rate in the intervention group receiving melatonin was about 40%, while it was 14% in the control group (P < 0.05). Therefore, it was concluded that the clinical pregnancy rate increases with the increase in endometrial thickness ratio. Conclusions In general, administration of melatonin for 4 weeks in infertile women undergoing IUI cycle had beneficial effects on endometrial thickness, which was associated with better pregnancy outcome. Trial registration EU CT Nr IRCT20221127056633N1 2023,04,03. Registered on 3 April 2023.