Introduction It has been suggested that prenatal stress contributes to the risk of obesity later in life. In a population-based cohort study, we examined whether prenatal stress related to maternal bereavement during pregnancy was associated with the risk of overweight in the offspring in young adulthood.

Methods We conduct a cohort study of 109 919 Danish men who were born in 1986-1990 and presented for conscription in 2006–2009. By linkage of the conscription file (“session”) and national registers, we identified 4549 conscripts who were exposed to prenatal stress, defined by being born to mothers who were bereaved by death of a close family member from 1 year before pregnancy until birth of the child. Differences in the means in Body mass index and RR of overweight between the exposed and the un-exposed were analysed by GLM regression or Logistic regression in SAS.

Results Body mass index values and prevalence of overweight were higher in the exposed group. The overall adjusted OR for overweight was 1.13 (95% CI 1.04 to 1.23). The highest OR was observed in the subjects whose mothers lost a child or husband during pregnancy (OR 1.35, 95% CI 1.07 to 1.71).

Conclusions Our results suggest that severe pre-pregnancy stress is associated with an increased risk of overweight in the offspring in young adulthood.