This study aimed to investigate the associations between the post-wash total progressively motile sperm count (TPMSC) in the first intrauterine insemination (IUI) cycle and pregnancy outcomes of the second IUI cycle. Data were retrieved from the clinical database at the Reproductive Center of Peking University Third Hospital (Beijing, China) between January 2011 and December 2022. Couples were included in this retrospective cohort study if they had unexplained or mild male factor infertility and were treated with IUI for two consecutive cycles using the same protocol. A total of 8290 couples were included in the analysis. The mean ± standard deviation (s.d.) age of women was 32.0 ± 3.5 years. We categorized groups based on the post-wash TPMSC (×106) levels in the first IUI cycle: group 1 (0 < TPMSC < 1, n = 1290), group 2 (1 ≤ TPMSC < 2, n = 863), group 3 (2 ≤ TPMSC < 3, n = 800), group 4 (3 ≤ TPMSC < 4, n = 783), group 5 (4 ≤ TPMSC < 5, n = 1541), group 6 (5 ≤ TPMSC < 6, n = 522), group 7 (6 ≤ TPMSC < 7, n = 547), group 8 (7 ≤ TPMSC < 8, n = 175), group 9 (8 ≤ TPMSC < 9, n = 556), group 10 (9 ≤ TPMSC < 10, n = 192), and group 11 (TPMSC ≥ 10), n = 1021). The primary outcome was live birth rate of the second IUI cycle. Live birth rates were 7.9%, 5.8%, 7.6%, 7.4%, 7.3%, 8.4%, 7.5%, 7.4%, 8.8%, 8.9%, and 7.6% in each group, respectively. There were no statistically significant differences in clinical pregnancy rates or live birth rates between any groups and those with the post-wash TPMSC <1 × 106. In an IUI program for unexplained and mild male factor infertility, the post-wash TPMSC in the first IUI cycle was not significantly associated with the live birth rate in the second IUI cycle.

Keywords: infertility; intrauterine insemination; live birth; semen analysis; total progressively motile sperm count