June 27, 2007–Taking antidepressants during pregnancy doesn’t greatly
increase the overall risk of most birth defects, new research shows.
But taking specific antidepressants may slightly increase the risk of
certain birth abnormalities, the researchers say.
The two new studies, published in the June 28 issue of The New England
Journal of Medicine, examined a type of popular antidepressants called
SSRIs, or selective serotonin reuptake inhibitors. The drugs work by making
more of the brain chemical serotonin available to the brain, thought to help in
boosting mood.
While the results from the two studies are at odds on some points, they are
in agreement on others. Paxil, for instance, was found to be strongly
associated with specific defects. And the risks of certain birth defects, while
increased, are still very small, the researchers say.
Concerns about birth defects associated with SSRI use began to surface three
years ago, says Carol Louik, ScD, assistant professor of epidemiology at Boston
University, Boston, and an author of one study. But research on SSRI use during
pregnancy has produced mixed findings.
“There have been several studies in the past that have found an
association between several SSRIs and certain birth defects, such as heart
defects,” says Jennita Reefhuis, PhD, an epidemiologist with the National
Center on Birth Defects and Developmental Disabilities for the CDC, and a
co-author of the other new study.
In 2005, the FDA alerted doctors and patients that the SSRI Paxil had been
found to increase the risk of birth defects, especially heart defects, when it
was taken during the first three months of pregnancy.
The new studies don’t answer the question about the safety of SSRI use
during pregnancy definitively, but they do add valuable information for women
trying to decide. Both studies should reassure women, Louik and Reefhuis
say.
CDC Study Details
Reefhuis’ team evaluated data from 9,622 infants born with major birth
defects and 4,092 infants born without birth defects, all delivered during the
years 1997-2002. The data was obtained through the CDC-funded National Birth
Defects Prevention Study, an ongoing effort that collects information from
eight states.
The mothers participated in a telephone interview, answering questions about
their exposure to antidepressants during pregnancy and one month before. In
all, 3% of them, or 408, reported use of SSRIs during pregnancy or one month
before they conceived.
The researchers evaluated four SSRIs, including Prozac, Zoloft, Paxil, and
Celexa. Overall, no significant associations were found between the mother’s
use of the SSRIs and congenital heart defects, Reefhuis says. But they did find
that Paxil use was linked to one type of heart defect, called right ventricular
outflow tract obstruction defect, she says.
And they found an overall association between SSRIs and three other types of
birth defects:

Anencephaly. A defect in which the neural tube fails to close. The
neural tube is a narrow channel that normally closes about the fourth week of
pregnancy to form the brain and spinal cord.

Craniosynostosis. A defect in which the joints between the
bones of the skull close prematurely before brain growth is complete.
Mental retardation can occur.

Omphalocele. An abdominal wall defect in which intestines and other
organs can protrude.

The increased risk ranged from 2.4 to 2.8 times higher, she says. But the
numbers of infants affected, in each case, were small, she says. naprosyn. For instance,
nine of the 214 born with anencephaly were exposed to SSRIs.

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