Losing a loved one during pregnancy may affect the mental health of the child as he or she grows into adulthood, according to a study by two Stanford researchers.

“We find that prenatal exposure to the death of a maternal relative increases take-up of ADHD medications during childhood and anti-anxiety and depression medications in adulthood,” wrote the researchers—Maya Rossin-Slater, PhD, assistant professor of health research and policy, and Petra Persson, PhD, assistant professor of economics—in the study, published in the April issue of the American Economic Review.

“Of course, you cannot prevent family members from dying, and we certainly do not want our findings to constitute yet another source of stress for expecting mothers, who already face rather intense pressure to eat the right foods, avoid activities deemed harmful, and experience an avalanche of health advice,” Persson said. “But our findings potentially point to the importance of generally reducing stress during pregnancy, for example through prenatal paid maternity leave and programs that provide resources and social support to poor, pregnant women.”

Their research focused specifically on singleton children in Sweden born between 1973 and 2011 whose mothers lost close relatives during their pregnancies. They used population registers to construct family trees that span four generations, from the children to their maternal great-grandparents. Their sample included all children whose mother lost a close relative—a sibling, parent, maternal grandparent, the child’s father, or her own older child—in the 9 months after the child’s date of conception or the year after the child’s birth. The study did not account for the quality of those relationships.

Their analysis compared the outcomes of children whose mothers experienced a relative’s death while they were pregnant with those of children whose maternal relatives died in the year after birth. They were thus able to isolate the impacts of fetal exposure to maternal stress from bereavement from all other consequences associated with a family member’s death, such as changes to family resources or household composition, which affect all children in their sample.

Additionally, by considering the deaths of different relatives, the researchers’ approach presents a new measure of intensity of stress exposure: the closeness between the mother and the relative who passed in the family tree.