Researchers have previously shown that severe stress experienced by pregnant women can lead to weight problems for children between 10 and 13 years; however, a correlation between the mother's level of stress during pregnancy and the risk of developing overweight or obesity as an adult is new.
"Overall our results indicate that stress can create a programming of the unborn child that makes it susceptible to putting on weight after birth," said Lena Hohwu from the Department of Public Health at Aarhus University, Denmark.
The study is based on data from 119,908 young men who were summoned to the Danish conscription examination between 2006-2011, during which their body mass index or BMI was measured.
The researchers focused on women who experienced the death of a close relative just before or during the pregnancy. They subsequently followed the women's male children until early adulthood.
Young men whose mothers had been exposed to bereavement had - depending on the relation of the relative to the mother - different degrees of increased risk of overweight and obesity.
If the woman had lost her husband, her son had twice the risk of developing overweight in adulthood.
"We have specifically investigated the stress factor that occurs when the child's mother loses a close relative just before or during pregnancy, that is, before the child is born," Hohwu said.
"We have designated this as 'an indicator of severe stress' that can double the risk of developing obesity in adulthood," said Hohwu.