Dads have long gotten short shrift in studies of babies' early development. Indeed, some have even argued that men's lack of a "maternal instinct" means they do not bond as well with their children, so have excluded them from research on how parental behavior influences development. Yet men, like women, sometimes become depressed after the birth of a child. British researchers sought to give fathers equal time, looking at whether that kind of postpartum depression affected their kids.

What the researchers wanted to know: Does a father's postnatal depression influence his baby's development?

What they did: The researchers surveyed more than 13,000 pregnant women and many of their partners. The new dads were asked about a range of issues, including their mood before and after the baby was born. They were also surveyed eight weeks later to see whether they were suffering from postpartum depression. (The researchers took measures to rule out long-term depression.) Finally, the researchers questioned the mothers when their children were 31/2 years old, to find out whether the kids had behavioral or emotional problems.

What they found: Dads who were depressed just after their babies were born were more likely to have children with behavioral problems later, including hyperactivity. Boys were more likely than girls to have later problems when their dads experienced postnatal depression, especially when it came to behavior problems such as fighting with other children. The effects of the father's postnatal depression remained even when the researchers controlled for the mother's postnatal depression and the father's long-term depression.

What it means to you: Dad matters too! Just as mothers' moods can affect their babies' long-term development, fathers can also influence it. New dads should pay attention to how they are feeling and seek help if they experience symptoms of postnatal depression such as prolonged feelings of sadness or loss, tiredness, and lack of interest in activities.

Caveats: The researchers used mailed surveys to get all of their information for the study, which are generally not thought to be as accurate as examinations or in-person interviews.

Find out more: KidsHealth.org has a website that focuses on mothers' risks of postpartum depression but also talks about when fathers might be at risk.

Postpartum Education for Parents also has a good site that includes information for new parents on postpartum depression, though, like most sites, it concentrates on women's problems with depression.

Read the article: Ramchandani, P., et al. "Paternal Depression in the Postnatal Period and Child Development: A Prospective Population Study." The Lancet. June 25, 2005, Vol. 365, No. 9478, pp. 2201-2205.

Abstract online: http://www.thelancet.com