Male age negatively influences clinical pregnancy rate in women younger than 40 years undergoing donor insemination cycles.

The influence of paternal age on clinical pregnancy was examined within younger patients undergoing donor insemination (DI) cycles in Western Australia. A retrospective analysis of 2142 DI cycles was carried out, including only women <40 years with no history of fertility problems. Logistic regression analysis was used to relate donor age to clinical pregnancy rate. Proportional hazards regression analysis was used to relate male age to time to pregnancy. Mediation analysis was conducted to adjust for influence of sperm concentration and motility. Analysis was controlled for female age, luteal-phase progesterone support and insemination year. There was no effect of female age on pregnancy rate or time to pregnancy. Older males (age ≥ 45 years) were significantly associated with a reduced pregnancy rate and longer time to pregnancy. Mediation analysis indicated that sperm concentration and motility did not fully account for the effect of male age on pregnancy. This study reveals an adverse effect of male age on clinical pregnancy in women <40 years of age that is not solely mediated by decreased sperm concentration or motility. This has implications for recruitment systems that attract older donors such as open-identity systems, which may benefit from actively recruiting younger donors.