Semen parameters' mediation effect on the association between advanced paternal age and IVF clinical outcomes: A...

To explore the mediation between advanced paternal age and the outcomes of in vitro fertilization (IVF) in a female-adjusted cohort.

The study retrospectively included couples undergoing IVF cycles between 2011 and 2020, and whose female partner was free of medical conditions that would significantly worsen clinical outcomes. Data on patient medical conditions, clinical data, and follow-up information were collected. Causal mediation effect analysis adopting both linear/logistic regression and mixed-effects models was carried out to evaluate the effect of paternal age on the outcomes.

21,959 IVF cycles were included in the study. Semen volume, sperm motility and sperm morphology were significantly associated (P value <0.05) with paternal age. A lower fertilization rate was associated with increased paternal age after adjustment for maternal age (adjusted OR = 0.800; 95 % CI, 0.678, 0.943; P value = 0.008). Mediation analysis revealed that A-level sperm rate and progressive rate respectively mediated 37.0 % and 41.0 % of the association between paternal age and fertilization rate.

Sperm motility rate, especially A-level sperm rate and rapid progressive rate, mediated the association between advanced paternal age and lower fertilization rate in the cycles.