The loss of a close relative is one of the most stressful life events. In pregnancy, this experience has been associated with a higher risk of fetal death and under-five mortality, but little is known about potential effects on long-term mortality in offspring. We examined the association between prenatal maternal bereavement and mortality in a cohort of 5.3 million children followed until up to 37 years of age.

The population-based cohort study included 5 253 508 live singleton births in Denmark (1973–2004) and Sweden (1973–2006). Children born to mothers who lost a child, spouse, sibling, or parent during or 1 year before pregnancy were categorized as exposed.

Prenatal maternal bereavement was associated with a 10% increased all-cause mortality risk in offspring [mortality rate ratio (MRR) 1.10, 95% confidence interval (CI) 1.03–1.18]. The association was the most pronounced for children of mothers who lost a child/spouse (MRR 1.28, 95% CI 1.14–1.44) and was stronger during the first 10 years of life. Prenatal maternal bereavement may have stronger effects on natural causes of death in offspring, including infectious/parasitic disease (MRR 1.86, 95% CI 1.07–3.23), endocrine/nutritional/metabolic diseases (MRR 3.23, 95% CI 2.02–5.17), diseases of nervous system (MRR 3.36, 95% CI 2.47–4.58), and congenital malformations (MRR 1.39, 95% CI 1.08–1.80). No excess mortality risk in offspring was observed for unnatural causes of death.

Prenatal maternal bereavement was associated with an increased long-term mortality risk in offspring, particularly for selected natural causes of diseases and medical conditions. Our results support the fetal programming hypothesis that prenatal stress may contribute to ill health from physical diseases later in life.