They might relish becoming parents, but they can also be unprepared for the infant in their lives. They're sleep-deprived, confused and irritable. They're the fathers.

Discussions of the connection between mental health and childbirth have long focused on women, but a sizeable portion of men experience prenatal and postpartum depression too, according to research released Tuesday.

The study, published in the Journal of the American Medical Assn., found that 10.4% of men experienced serious depression at some point between his partner's first trimester and one year after childbirth, more than double the depression rate for men in general. American men were more likely to experience prenatal or postpartum depression compared with men in other countries, 14.1% in the U.S. compared with 8.2% internationally.

"It's viewed as a disorder of motherhood. It's not viewed by health professionals and the public as a problem in fathers," said James F. Paulson, the lead author of the study and an assistant professor of pediatrics at Eastern Virginia Medical School in Norfolk.

But depression in either parent can affect both the couple's relationship and the child's development, Paulson said, adding that further study is needed.

"There have been a few very good studies documenting negative child outcomes when fathers are depressed," he said. "That alone makes this a significant public health concern and something we need to pay more attention to."

Paulson analyzed the findings of 43 studies involving 28,004 participants. The men were from the United States, China, Ireland, Britain, Australia and several other developed nations.

The most vulnerable period for depression in men was three to six months postpartum, he found, with a quarter of the men who experienced depression afflicted during this time period.

An estimated 14% to 23% of women experience depression during pregnancy and 5% to 25% have postpartum depression, according to the American College of Obstetricians and Gynecologists.

Paternal depression has not been well documented historically, and many of the studies in the meta-analysis were conducted only in the last five to 10 years, Paulson said. The contemporary father may be more vulnerable to this malady than previous generations of fathers because of the increasing number of women in the workplace and the corresponding expectations that he shoulder more responsibilities at home.

"We are expecting dads to be more involved in parenting than we ever have before," said Will Courtenay, a psychotherapist and researcher on paternal depression in Berkeley who was not involved in the study. "Most dads are welcoming of that, but they don't have any models about what a dad is supposed to do. That creates uncertainty, and that uncertainty can lead to anxiety and depression."

Further, paternal depression symptoms are much less likely to be recognized than maternal depression, Paulson said. A woman may be sad, withdrawn and weepy while depressed; men may appear more irritable or angry and become detached from the family.

In women, the condition is often linked to biological and hormonal changes associated with pregnancy and birth. But hormones are not the sole cause of pregnancy-related depression even in women.

"This narrow focus really makes it difficult to understand depression in men," Paulson said. "We know, in fact, there are many factors, hormonal and other, related to depression in women."

The depression of either parent can include how one partner's depression affects the other and how intimacy, conflict management and division of responsibilities change after having a baby. In the meta-analysis, men had a higher risk of depression if their partner also had depression.

"If we see depression in one partner that should prompt us to screen for depression in the other partner," he said.

Marital dissatisfaction, financial stress and having a sick or colicky baby could increase the risk of depression in one or both partners, said Courtenay, who is conducting a study on new fathers in collaboration with the Center for Men at McLean Hospital in Belmont, Mass.

"Sleep deprivation likely plays one of the biggest roles for men and women," he said. "We know that if normal, healthy adults go without good sleep for just one month, they begin to show signs of clinical depression."