Women with a history of depression no longer have to worry about discontinuing treatment for their condition if they become pregnant, a new Yale study has found.

The research, conducted by a team at the School of Medicine, revealed that women who discontinue taking antidepressant medications during pregnancy face no greater risk of developing a depressive episode during or after term than they would have if they continued treatment. The study, published online and scheduled to appear in the November issue of the journal Epidemiology, followed a group of 778 pregnant women with a history of depression who decided independently whether or not to continue antidepressant medication throughout their term. Experts interviewed said the results of the study are important as little is known about the effects of antidepressant medications on fetal development.

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“This is very good news for women who are healthy,” said Kimberly Yonkers, lead author of the report and professor of psychiatry, obstetrics, gynecology and reproductive sciences at the School of Medicine. “A lot of women have concerns about exposing their fetuses to the effects of antidepressants, but the results of the study show that many who were afraid to stop taking antidepressants can do so fairly safely.”

The analysis was based on a larger cohort of 3,000 women, all over 18, with a history of depression throughout Connecticut and Massachusetts, whose progress was tracked through pregnancy and the post-partum period, Yonkers said. The women analyzed in this particular study did not face a major depressive episode during pregnancy, but had experienced at least one at some point in the past. Twenty-one percent of the 3,000 women were taking antidepressant medications at the start of pregnancy; only 14 percent continued treatment by their second trimester.

The decision to discontinue taking medication was a difficult one for many women in the study, as antidepressants have been previously linked to birth defects in the heart, lungs and brain, Yonkers said.

Yet, depression in women peaks during the child-rearing period, said Myrna Weissman, professor of epidemiology and psychiatry at the Columbia School of Public Health. As a result, a large proportion of new mothers have some history of depression, she said.

“It is still unclear what effects antidepressants have on children,” Weissman said. “On the other hand, the effects of a mother’s depression on the child and the fetus are dangerous as well and should not be overlooked.”

Factors other than medication proved to be better indicators of the likelihood of a depressive relapse, the researchers found.

The study revealed that women who experienced four or more major depressive episodes in their lifetimes or one episode within six months of pregnancy faced twice the risk of developing depressive symptoms again, regardless of their decision to continue medication. Minorities also appeared to face higher risks; black and Latina women were respectively 3.5 times and 2.5 times more likely to relapse than their Caucasian counterparts. The reason for this socioeconomic disparity is not yet understood, Yonkers said.

University of Illinois in Chicago psychiatry and mental health services professor Judith Cook said the problem with epidemiological research is that it relies upon previously existing data and cannot, for ethical reasons, set up experimental manipulations to more directly answer such large public health questions.

“The study’s methodology does not allow the researchers to rule out alternative explanations for their findings, such as the possibility that those women who were more likely to experience an episode of [major depressive disorder] were less likely to discontinue use of antidepressants during pregnancy,” Cook said.

The Yale team will next dissect the data to discover the effects of antidepressants on babies’ health, Yonkers said. Tracking both the health of babies born to mothers taken off antidepressants and the time before mothers first relapse would prove instructive in determining when mothers should restart their medication, Weissman said.

Any future research, Cook said, should highlight the need for integrated medical and mental health care for pregnant women who are at risk for major depression.

“Women need to work closely with their physicians to assess the risks and benefits of antidepressant use during pregnancy,” Cook said. “Pregnant women deserve to have all the evidence science has to offer — as well as support — to make this difficult decision.”

The study was funded by the National Institute of Child Health and Development. It comprised part of a larger NIH study on psychotropic medication use during pregnancy.