Although a variety of factors have been reported as affecting pregnancy rates after intrauterine insemination (IUI), there have been conflicting results on prognostic factors. This study aimed to determine predictive factors for pregnancy in patients undergoing the first four IUI cycles.
A total of 348 IUI cycles using clomiphene citrate or letrozole combined with gonadotropin, or gonadotropin only were analyzed. Baseline clinical characteristics, variables related to ovulation induction and sperm parameters were compared between pregnant (n = 54) and non-pregnant groups (n = 294). Logistic regression analysis was performed to identify factors that could predict a pregnancy.
The overall clinical pregnancy rate was 15.5% (54/348) per cycle and 30.0% (54/180) per couple. During the first four IUI cycles, logistic regression analysis revealed that woman who were 39 years or older (OR: 0.263, 95% CI: 0.076-0.906, p = 0.034), longer duration of infertility (OR: 0.967, 95% CI: 0.942-0.993, p = 0.012), endometriosis (versus unexplained infertility; OR: 0.177, 95% CI: 0.040-0.775, p = 0.022) and endometrial thickness below 7 mm (OR: 0.114, 95% CI: 0.015-0.862, p = 0.035) were unfavorable factors to predict clinical pregnancy.
Women with old age, longer duration of infertility, the presence of endometriosis or thin endometrium in the preovulatory phase may have unfavorable outcomes during the first four IUI cycles.