Vitamin D improves endometrial thickness in PCOS women who need intrauterine insemination: a randomized double-blind placebo-controlled trial

To determine whether administration of vitamin D affects the success rates of intra uterine insemination (IUI) in infertile polycystic ovarian syndrome (PCOS) women and their endometrial thickness. This randomized, double-blind, placebo-controlled trial was conducted in an infertility clinic of Women's Hospital, and 110 infertile PCOS patients undergoing IUI were randomly divided to receive vitamin D or placebo. Endometrial thickness, IUI results, number of dominant follicles, duration of IUI cycle, and dose of HMG used in IUI were determined. The endometrial thickness was significantly different in the group treated with vitamin D versus the placebo group (p = 0.003). There was no statistical difference in pregnancy out come between the two groups (RR = 1.167, CI 95 % 0.70-1.93). No statistical difference was found in number of dominant follicles (p = 0.96), duration of IUI cycles (p = 0.70) and dose of HMG used for IUI (p = 0.95). It seems that administration of vitamin D induces endometrial proliferation in PCOS women during IUI cycle.