Reproductive function in the sons of women who experienced stress due to bereavement before and during pregnancy: a...

To estimate the association between prenatal exposure to maternal stress and reproductive disorders in Danish men, where prenatal stress exposure was defined as the mother's loss of a close relative during pregnancy or in the 12 months before conception.

Population-based cohort study.

Not applicable.

All males born in Denmark between 1973 and 2008 (n = 1,217,576) and observed for up to 39 years.

None.

Male reproductive function, defined using a composite outcome including congenital malformations of genital organs, testicular cancer, diagnosis of male infertility, or assisted conception use due to male factor infertility.

In total, 28,986 men (2.4%) had been exposed to prenatal stress, and 62,929 (5.2%) experienced the composite outcome during the follow-up period. Prenatal exposure to stress was associated with an elevated risk of reproductive problems (hazard ratio [HR] 1.09; 95% CI, 1.04-1.15). The association was stronger when the exposure occurred during the first trimester of pregnancy, and for congenital malformations of genital organs. When focusing on infertility alone, we saw no evidence of increased risk (HR 0.90; 95% CI, 0.77-1.06). In addition, the probability of marrying a woman was lower for exposed men (HR 0.93; 95% CI, 0.89-0.98).

Prenatal stress in the form of the mother's bereavement during the first trimester of pregnancy is associated with a higher risk of reproductive disorders from congenital malformations of the genital organs in the male offspring. The lack of an association between maternal bereavement and later infertility in the exposed male offspring may be due in part to the men's lower probability of attempting to have children.