Paternal age >or=40 years: an important risk factor for infertility.

Abstract

The purpose of this study was to examine the risk of infertility that is associated with paternal age, because this factor rarely has been investigated, whereas maternal age of >or=35 years is a well-known risk factor. This large, retrospective, population-based sample included 6188 European women (from Denmark, Italy, Spain, Germany) aged 25 to 44 years who were selected randomly from census registers in 1991 through 1993. Among couples composed of a woman aged 35 to 39 years, risks were significantly higher when paternal age was >or=40 years than when paternal age was <40 years, with an adjusted odds ratio of 2.21 (95% CI, 1.13, 4.33) for delay in pregnancy onset (failure to conceive within 12 months) and of 3.02 (95% CI, 1.56, 5.85) for difficulties in having a baby (failure to conceive within 12 months or pregnancy not resulting in a live birth). Like maternal age of >or=35 years, paternal age of >or=40 years should be considered to be a key risk factor for infertility.