Mother's age at birth may influence symptoms of depression in daughters

"This study suggests that older maternal age is associated with symptoms of depression, anxiety and stress in young adult females," said Jessica Tearne, a doctoral student at the University of Western Australia and lead author of the study. It appears in the Journal of Abnormal Psychology.

Tearne and her colleagues analyzed data from the Western Australian Pregnancy Cohort (Raine) Study. From 1989 to 1991, pregnant women were recruited into this study, and provided psychological and demographic information. The resulting offspring then underwent psychological assessment at various ages over the next 23 years.

In this study, the researchers looked at self-reported levels of various symptoms of depression, anxiety and stress from 1,200 of the offspring at age 20 and compared them with the age of the mother and father at the time the children were born. Daughters whose mothers were age 30 to 34 when they gave birth reported significantly higher levels of stress and those whose mothers were over age 35 at the time of birth had significantly higher levels of stress, depression and anxiety compared with daughters whose mothers were under age 30.

While 5 percent of the mothers were under age 20 when they gave birth, there was no effect for giving birth in that age group. The fathers' age at the time of birth also had no effect, and there was no effect found for sons.

While the exact cause of this relationship is not clear, Tearne said she suspects it is not necessarily biological. "One hypothesis is difficulties may occur in the mother-daughter relationship because of a large age difference between the two," said Tearne. "It may be that a 30 or more year age difference between mother and daughter leads to a significant difference in the value systems that may cause tensions in the relationship, leading to stress, worry and sadness in the child, particularly during the transition to young adulthood."

Another possible explanation may be that the women who gave birth over age 30 would be in their 50s at the time their children were assessed and therefore more likely to be experiencing health problems associated with aging. This could also lead to higher levels of symptoms in the children, Tearne said. Other studies have suggested that daughters are more affected by their mother's health problems than sons, which could explain why the effect only appears in daughters, she said.

"It is important to remember, too, that the study examined symptoms of distress, rather than clinical diagnosis," said Monique Robinson, PhD, of the University of Western Australia, another author of the study. "It could be that the offspring of older mothers are at risk for a few more symptoms of depression, anxiety and stress, but that does not necessarily mean they will experience a diagnosable mental disorder."