Impact of male partner’s age on IVF/ICSI pregnancy outcomes stratified by female age: a retrospective study of 1,703 treatment cycles

Increasing male age has been linked to reduced sperm quality and poorer pregnancy outcomes in assisted reproductive technolo (ART) cycles; however, the combined effects of both paternal and maternal ages remain controversial. A retrospective analysis of 1703 fresh embryo transfer cycles (January 2018–June 2024) was conducted. Females were stratified into < 35 years (n = 1,188) and ≥ 35 years (n = 515). Within each female age group, male partners were further subdivided into narrower age categories. Sperm parameters (concentration, progressive motility [PR%], normal morphology, DNA fragmentation index [DFI]) and pregnancy outcomes (clinical pregnancy rate, miscarriage rate, live birth rate) were compared using Mann-Whitney U test and chi-square test. Propensity score matching (PSM) adjusted for confounding factors. Among females age < 35 group, no significant associations were observed between male age and clinical pregnancy rate, miscarriage rate, or live birth rate (all P > 0.05). Although age 35 in males appeared to be a potential inflection point for changes in reproductive outcomes, comparative analysis revealed no statistically significant differences in pregnancy outcomes between men < 35 years and those ≥ 35 years. In female aged ≥ 35 years, increasing male age was significantly correlated with a lower live birth rate (P = 0.032). Compared to the < 40 years group, male age ≥ 40 years exhibited significantly higher miscarriage rates (32.5% vs. 21.8%, P = 0.039) and lower live birth rates (31.2% vs. 39.2%, P = 0.035). These trends persisted after PSM adjustment for confounders, with the age ≥ 40 years group demonstrating a 15.2% increase in miscarriage rate (37.2% vs. 22.0%, P = 0.026) and a 10.7% reduction in live birth rate (32.0% vs. 42.7%, P = 0.037). Notably, there were no significant differences in fertilization rate, good-quality embryo rate, or blastocyst formation rate across male age subgroups (all P > 0.05). Further analysis revealed that advanced male age was associated with significantly higher DFI abnormality rates. The high-DFI group showed increased biochemical pregnancy loss (11.7% vs. 5.2%) and miscarriage rates (38.0% vs. 20.9%), with significantly elevated DFI levels in the miscarriage group versus non-miscarriage group (P = 0.030). However, DFI showed no significant correlation with embryo quality parameters or clinical pregnancy rate. This retrospective analysis demonstrates that the impact of male age on IVF/ICSI outcomes is dependent on the female partner’s age. Specifically, male age is not significantly correlated with clinical outcomes when the female partner is under 35 years; however, among female age ≥ 35 years, advanced male age is associated with increased miscarriage rates and decreased live birth rates. Sperm DNA damage may contribute to these adverse outcomes observed in older female partners. Therefore, careful evaluation and management of sperm DNA integrity should be prioritized in clinical practice.