To explore the clinical factors related to the live birth rate of intrauterine insemination (IUI).

A retrospective cohort study was conducted in 9077 patients treated with IUI for 15 740 cycles in Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital from January 2015 to December 2018. The effects of female age, duration of infertility, types of infertility, factors of infertility, protocols and times of cycles, time of insemination, forward motile sperm concentration after treatment and the number of broken eggs on the live birth rate were analyzed. The difference of live birth rate of different number of broken eggs in ovulation induction cycle was analyzed.

A total of 1784 clinical pregnancy cycles were obtained in 15 740 IUI cycles, with a clinical pregnancy rate of 11.3% (1784/15 740) and a live birth rate of 8.5% (1339/15 740). In univariate analysis, among the age factors, the live birth rate of different aged patients was significantly different [<30 years old 10.62% (462/4349), 30-35 years old 8.27% (748/9048), >35 years old 5.51% (129/2343), P<0.001]. Among the factors of infertility, the live birth rate of the female factors [11.51% (357/3101)] was significantly different from the male factors [8.14% (337/4142)], the bilateral factors [8.09% (216/2670)] and the unexplained factors [7.36% (429/5829)] after IUI treatment (P<0.001). The live birth rate in the ovulation induction cycle [10.19% (850/8343)] was different from that in the natural cycle [6.61% (489/7397), P<0.001)]. In the No.of oocytes ovulated group, the live birth rate when the number of ovulation was ≥3 [11.80% (19/161)] was significantly different from that in the groups with ovulation number of 1 and 2 [8.31% (1233/14 837), 11.73% (87/742), P<0.001)]. There were no significant differences in different types of infertility, time of insemination, forward motile sperm concentration after treatment, duration of infertility and time of insemination. Multivariate analysis showed that female age (OR=0.766, 95% CI=0.700-0.838), factors of infertility (male factor OR=0.762, 95% CI=0.649-0.893, bilateral factors OR=0.759, 95% CI=0.634-0.909 and unexplained factors OR=0.708, 95% CI=0.608-0.824), protocols (OR=1.421, 95% CI=1.260-1.604) and the number of broken eggs (OR=1.206, 95% CI=1.018-1.430) were independent factors affecting the live birth rate of IUI. Compared with the difference of the live birth rate of different number of broken eggs in the ovulation induction cycle, the live birth rate of the ovulation number of 2 [13.45% (83/617)] was higher than that of 1 or more than 3 ovulations [9.89% (750/7582), 11.81% (17/144), P=0.016].

The female age, the type of infertility, the different protocols and the number of broken eggs are the independent factors affecting the live birth rate of IUI. The female age <30 years old, ovulation induction cycle, and the number of broken eggs ≥3 are independent factors of live birth rate in IUI patients. In the ovulation induction cycle, the live birth rate was the highest when the number of broken eggs was 2.

Insemination, artificial, homologous; Infertility, female; Live birth rate