This study aims to analyze the effect of the body mass index (BMI) on E2, P and LH values in females who received intrauterine insemination (IUI) treatment on human chorionic gonadotropin (HCG) day. Methods: A total of 2319 cycles of IUI-assisted pregnancy treatment were selected in our hospital. Based on the BMI, female infertility patients are divided into three groups: normal weight group, overweight and obese group.