WEDNESDAY, June 27 (HealthDay News) -- Pregnant women who use antidepressants known as selective serotonin reuptake inhibitors (SSRIs) are not increasing the risk of most birth defects for their newborns, new research suggests.
Drugs within this class -- which include Celexa, Paxil, Prozac and Zoloft -- may increase the risk for certain defects, but, even then, the absolute risk is extremely small, concluded two studies published in the June 28 issue of the New England Journal of Medicine.
"It's a fairly reassuring message for women who need antidepressants and are pregnant or who plan on becoming pregnant," said Carol Louik, lead author of the first paper and an assistant professor of epidemiology at Boston University's Slone Epidemiology Center. "We saw no large risks, and the fewer elevated risks that we did see would only lead to very small absolute risks."
"This is a valuable contribution," added Dr. Jon Shaw, director of child and adolescent psychiatry at the University of Miami's Miller School of Medicine. "It substantiates the need to always be prudent in prescribing antidepressants."
The issue of maternal use of antidepressants, particularly those known as selective serotonin reuptake inhibitors (SSRIs) is a charged one.
Last November, the American College of Obstetricians and Gynecologists recommended that women avoid the SSRI Paxil if they are pregnant or planning on becoming pregnant, due to a potential heightened risk of birth defects.
The guidelines come a year after the U.S. Food and Drug Administration (FDA) issued a warning about possible birth defects associated with Paxil when the drug is taken during the first trimester of pregnancy.
The initial FDA warning came in September of 2005. In December of the same year, the FDA instructed Paxil's maker, GlaxoSmithKline, to reclassify the drug from a Category C to D (a stronger warning) for pregnant women. Category D means studies in pregnant women have demonstrated a risk to the fetus.
Other reports had indicated that SSRIs may cause newborns to have withdrawal symptoms.
To complicate matters further, yet another study found that pregnant women who discontinued their antidepressant medication were five times more likely to relapse into depression than women who continued with the medication.
Women of reproductive age have the highest prevalence of major depressive disorders, with experts estimating that about one in 10 will experience a bout of major or minor depression sometime during pregnancy or the postpartum period.
The first study, conducted by Louik's team of Boston researchers, looked at almost 10,000 infants with birth defects and close to 6,000 infants without birth defects. The researchers wanted to see if there was an association between defects that had been previously linked to SSRIs and the use of these drugs by mothers during their first trimester of pregnancy.
Overall, SSRI use was not associated with significantly increased risks of craniosynostosis (when connections between skull bones close prematurely), omphalocele (when intestines or other abdominal organs protrude from the navel) or heart defects.
There were, however, associations between maternal use of Zoloft (sertraline) and omphalocele and septal defects (defects in the walls that separate the chambers of the heart) and between Paxil and defects that interfere with blood flow to the lungs.
But even if a certain drug increased rates by a factor of four, the risk of having a child affected by the problem would still be less than 1 percent, the researchers said.
The study was funded by grants from the U.S. National Institute of Child Health and Human Development and the U.S. National Heart, Lung, and Blood Institute, as well as drug companies Aventis, Sanofi Pasteur and GlaxoSmithKline (maker of Paxil).
A second study, this time conducted by scientists at the U.S. Centers for Disease Control and Prevention (CDC), Atlanta, found that the use of SSRIs during the first trimester of pregnancy was not associated with any increased risks of most categories of birth defects, including congenital heart defects.
The researchers looked at four SSRIs: fluoxetine (Prozac), sertraline (Zoloft), Paxil and citalopram (Celexa).
There were some associations between maternal SSRI use and anencephaly (a brain defect), craniosynostosis and omphalocele, but, again, the absolute risk was very small. These defects had not previously been associated with SSRI use during pregnancy, the study authors noted.
Louik said she did not anticipate any labeling changes based on these studies, but that she did anticipate more research.
"These studies make a large contribution to the field, but they're not the final word by any means," she said.
There's more on treating depression during pregnancy at the March of Dimes.
SOURCES: Carol Louik, Sc.D., assistant professor of epidemiology, Slone Epidemiology Center, Boston University; Jon A. Shaw, M.D., professor and director, child and adolescent psychiatry, University of Miami Miller School of Medicine; June 28, 2007, New England Journal of Medicine