CHICAGO -- New mothers face increased risks for a variety of mental problems, not just postpartum depression, according to one of the largest studies of psychiatric illness after childbirth.
New fathers aren't as vulnerable, probably because they don't experience the same physical and social changes associated with having a baby, the researchers and other specialists said.
The study, based on medical records of 2.3 million people over a 30-year period in Denmark, found that the first three months after women have their first baby is riskiest, especially the first few weeks. That's when the tremendous responsibility of caring for a newborn hits home.
During the first 10 to 19 days, new mothers were seven times more likely to be hospitalized with some form of mental illness than women with older infants.
Compared with women with no children, new mothers were four times more likely to be hospitalized with mental problems.
New mothers also were more likely than other women to get outpatient psychiatric treatment.
However, new fathers did not have a higher risk of mental problems when compared with fathers of older infants and men without children.
The prevalence of mental disorders was about 1 per 1,000 births for women and just 0.37 per 1,000 births for men.
Mental problems included postpartum depression, but also bipolar disorder, with alternating periods of depression and mania; schizophrenia and similar disorders; and adjustment disorders, which can include debilitating anxiety.
The study underscores a need for psychiatric screening of all new mothers and treatment for those affected, said an editorial accompanying the study in today's Journal of the American Medical Association.
Two of the three authors of the editorial reported financial ties to the psychiatric drug industry. The researchers said they had no financial ties to the industry.
They examined national data on Danish residents from around 1973 to July 2005. About 1.1 million participants became parents during the study.
A total of 1,171 mothers and 658 fathers -- none diagnosed with any previous mental problems -- were hospitalized with a mental disorder after childbirth.
Lead author Trine Munk-Olsen, a researcher at Denmark's University of Aarhus, said similar risks for psychiatric problems probably would affect new parents in other developed nations including the United States.
However, differences in screening practices and access to healthcare might influence whether parents elsewhere are hospitalized, she said.
Physical changes after childbirth might partly explain why women are vulnerable, including fluctuating hormone levels, Munk-Olsen said.
These, alone or combined with sleep deprivation and the demands of breast-feeding, could trigger mental problems, she said.
Hard data on the number of women worldwide affected by postpartum mental illness are scant, but postpartum depression alone affects about 15 percent of US women.
The condition made headlines last year when actress
Postpartum mental illness also has been cited as a factor in shocking cases of mothers killing their children, including Andrea Yates's drowning of her five children in Texas in 2001.
Dr. Nada Stotland, a psychiatry professor at Rush Medical College in Chicago, said gender differences in postpartum mental illness are not surprising.
Mothers generally bear the brunt of sleep deprivation, and many new mothers are socially isolated or live far from relatives who could provide support, Stotland said.