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Infants
born to women taking commonly prescribed antidepressants
during the first trimester of their pregnancies have an
increased risk of serious birth defects, though the
danger remains tiny, according to two published studies
published.
The
reports in the New England Journal of Medicine
found a higher risk of developmental problems affecting
the intestines, brain and skull. Although
life-threatening, all of the defects are rare and
normally occur in no more than one in 2,500 births.
“The
take-home message is that we are talking about very
small risks,” said UC San Diego epidemiologist Christina
Chambers, who has studied the effects of antidepressants
but wasn’t involved in the new research.
The
studies are the latest to raise concerns about the
effects of antidepressants on fetuses.
Babies
born to women on antidepressants have been shown to
experience signs of withdrawal, including tremors and
sleep disturbances, during the first days of life.
Other
studies have linked a mother’s antidepressant use later
in pregnancy to an increased risk of lung problems in
newborns. Two reports have tied the drug Paxil, i n
particular, to a higher rate of congenital heart
malformation. The drug carries a warning about heart
defects.
The
latest studies were the largest yet to analyze the
association between antidepressants and birth defects.
The
findings could complicate decisions by pregnant women
about whether to use or continue taking antidepressants,
because untreated depression also carries risks and can
lead to smoking, drinking and other harmful behaviors.
An estimated 10 percent of pregnant women have
depression, according to previous research.
Women
should not discontinue antidepressants without first
talking with their doctors, the researchers said.
The
studies focused on antidepressants known as selective
serotonin reuptake inhibitors, a class that includes
Paxil, Prozac, Zoloft and Celexa. The medications work
by enhancing the activity of the brain chemical
serotonin. They have become the standard treatment for
depression since their introduction in the 1980s.
In
addition to acting on the brain to improve mood,
serotonin constricts blood vessels and performs other
functions. The full impact of manipulating serotonin
levels within the body isn’t completely understood,
although animal studies have detected a role for
serotonin in prenatal development of the heart and head.
Taken
together, the two studies looked at 19,471 infants with
birth defects and compared them with 9,952 normal
babies. Researchers examined which antidepressants
mothers had taken during the first trimester and
searched for patterns among dozens of different birth
defects reported.
The
studies found that Paxil tripled the risk of a heart
defect that reduces blood flow to the lungs, though the
chance of developing such a defect was less than 1
percent, according to an editorial published with the
reports. No other antidepressants were linked to cardiac
problems.
Dr.
Victoria Hendrick, a UCLA psychiatrist who was not
involved in the research, said it was reassuring that
cardiac malformations weren’t found with most of the
drugs.
But the
findings “add to our concern about Paxil in pregnancy,”
said Hendrick, who has received speaking fees from
Zoloft manufacturer Pfizer Inc.
The two
studies differed in other respects.
One of
the reports, funded in part by Paxil maker
GlaxoSmithKline, associated Zoloft with a nearly sixfold
increase in cases of omphalocele, in which intestines or
other abdominal organs protrude from the navel. The
birth defect is very rare, occurring in one of every
5,000 births, according to federal statistics.
The
finding was based on three cases in which infants with
the intestinal defect had been exposed to Zoloft — not
enough to draw firm conclusions, said Carol Louik, a
Boston University epidemiologist and lead author of the
study.
The
other study linked antidepressant use to a doubling of
the risk of three congenital problems: anenecephaly, a
defect in which a large portion of the brain and skull
is missing; craniosynostosis, in which connections
between skull bones close prematurely; and intestinal
defects.
The
researchers, from the Centers for Disease Control and
Prevention and the University of British Columbia in
Vancouver, Canada, cautioned that their findings were
based on only a handful of cases.
The
risks appeared greater for obese women who used
antidepressants, said Dr. Sonja A. Rasmussen of the CDC,
a coauthor of the study.
Although
obesity itself is a risk factor for some kinds of birth
defects, antidepressants appeared to increase that risk.
One possible reasons is that antidepressants dissolve in
fats and so they may work differently in women who are
obese, she said. |
