By Robert Preidt
Researchers followed 1,200 Australians born between 1989 and 1991 for two decades. They found that daughters born to mothers who were aged 30-34 had higher levels of stress at age 20 compared with those born to younger mothers.
A mother's age at the time of birth had no effect on sons, and the father's age at the time of birth had no effect on either daughters or sons, according to the findings published recently in the Journal of Abnormal Psychology.
But scientists only observed an association between a mother's age at childbirth and her daughter's mental state as an adult. The study did not prove a cause-and-effect link.
"This study suggests that older maternal age is associated with symptoms of depression, anxiety and stress in young adult females," said lead author Jessica Tearne, a doctoral student at the University of Western Australia.
She said it's not known why daughters born to older mothers might be at increased risk for stress, anxiety and depression, but 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," Tearne said in a journal news release. "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."
It's also possible that women who give birth after age 30 are in their 50s when their children are young adults and more likely to have age-related health problems, which could have a negative effect on their children.
Previous research has suggested that daughters are more affected by their mother's health problems than sons.