Effect of Advanced Paternal Age on Reproductive Outcomes in IVF Cycles of Nonmale Factor Infertility: a Retrospective Cohort Study

Abstract Background: Female age over 35 years has been considered a determinant factor and increases the risk of infertility. However, paternal age has been virtually ignored, and its potential role is still poorly investigated. There is no current consensus on the effects of paternal age on assisted reproductive technology（ART）outcomes. Methods: In total, 381 in vitro fertilization (IVF) cycles of nonmale factor infertility (paternal age <35 y in 261 cycles, 35– 39 y in 72 cycles and ≥ 40 y in 48 cycles) were involved in this retrospective cohort study. Maternal age was controlled at under 35 years old. Embryo quality, clinical and neonatal outcomes were compared.Results: Among different paternal age groups, fertilization rate and high-quality embryos were not significantly different (P> 0.05). Compared with the <35 y group, pregnancy rate was not significantly different in the 35–39 y group (P> 0.05), but significantly lower in the ≥ 40 y group(P < 0.05). Additionally, we found a statistically significantly lower implantation rate for men aged ≥40 years (18.8%) compared to the group of men aged <35 years (31.1%) and men aged 35-39 years (30.0%) (P <0.05). A declining trend in the live birth rate (30.6%, 21.7%, and 19.6%) was noted in the subgroups of paternal age (<35 y, 35-39 y, and ≥40 y) (P >0.05). The miscarriage rate was significantly higher in the 35–39 y (44.8%) than that in the <35 y group (21.0%)(P <0.05). While in the oldest group of paternal age ≥ 40 y, although miscarriage rate increased but not significantly different (P >0.05). There were no significant differences in the preterm birth or multiple pregnancy rates among the different paternal age groups (P >0.05). Ectopic pregnancy was only found in the paternal age <35 y group. There was no abnormality in the birth weight of newborns among the different male age groups. Conclusion: Paternal age over 40 years is a key risk factor that influences the ART success rate even with good semen parameters, though has no impact on embryo development.