Factors associated with clinical pregnancy and live birth in first intracytoplasmic sperm injection cycles: a retrospective cohort study from Mongolia

Evidence concerning factors associated with clinical pregnancy and live birth after intracytoplasmic sperm injection (ICSI) in Mongolia remains limited. This study evaluated these associations among women undergoing fresh embryo transfer in their first eligible ICSI cycle. This single-center retrospective cohort study screened 1,490 ICSI cycles performed between February 2017 and November 2023. After 332 exclusions, 1,158 eligible cycles formed the overall stimulation cohort. Retaining each woman’s first eligible cycle yielded 657 women, of whom 287 underwent fresh embryo transfer. Women were categorized by oocyte yield: ≤4 ( n = 44), 5–9 ( n = 125), 10–15 ( n = 96), and ≥16 ( n = 22). Separate multivariable logistic regression models evaluated factors associated with clinical pregnancy and live birth. Frozen embryo transfer outcomes were not followed. Among 287 first-cycle fresh embryo transfers, 111 resulted in clinical pregnancy (38.7%) and 90 in live birth (31.4%). Higher antral follicle count (AFC) was associated with clinical pregnancy (adjusted odds ratio [aOR] 1.206, 95% confidence interval [CI] 1.105–1.317; p < 0.001) and live birth (aOR 1.210, 95% CI 1.106–1.325; p < 0.001). Greater maternal age was associated with lower odds of live birth (aOR 0.911, 95% CI 0.851–0.974; p = 0.007); its adjusted association with clinical pregnancy did not reach statistical significance. Outcome rates did not differ significantly across oocyte-yield groups. The events-per-parameter ratios were borderline, particularly for live birth (approximately 8.2), increasing the risk of overfitting. Higher AFC was associated with clinical pregnancy and live birth, and greater maternal age with lower odds of live birth, in this first-cycle fresh embryo transfer cohort. These hypothesis-generating findings do not establish clinical prediction utility and cannot be generalized to cumulative live birth per initiated ICSI cycle. Prospective multicenter studies with standardized transfer-related data and model validation are needed.