Researchers at the U.S. Centers for Disease Control and Prevention say they've confirmed a link between some antidepressant drugs and birth defects.
They gathered data on 17,952 mothers whose children were born with birth defects and 9,875 mothers with children born without defects from 1997 to 2009.
More than 1,200 of the mothers reported using a class of antidepressants known as selective serotonin reuptake inhibitors, or SSRIs, from one month before conception through the first trimester of pregnancy.
Some birth defects occurred more frequently in babies born to women who took certain types of SSRI medications early in pregnancy, the CDC researchers report in their study published in the BMJ.
The SSRI most commonly reported by study participants was Zoloft (sertraline), followed by Prozac (fluoxetine) and Paxil (paroxetine), Celexa (citalopram) and Lexapro (escitalopram), the CDC said.
Zoloft, the most widely used, was not found to be associated with any increased risks, says study author Jennita Reefhuis, an epidemiologist with the U.S. National Center on Birth Defects and Developmental Disabilities at the CDC.
However, the study revealed "some birth defects occur two to three times more frequently among babies born to mothers who took paroxetine [Paxil] and fluoxetine [Prozac] in early pregnancy," she says.
The researchers emphasized that a link or an association does not prove a cause and effect and that women shouldn't stop taking such drugs.
"Depression can be very serious, and women should not suddenly stop taking their medications," Reefhuis says.
"Women should talk to their health care providers about available options, ideally before planning a pregnancy," she suggests.
Although previous studies had suggested possible links between Zoloft and five types of birth defects, the CDC researchers say they found no connection.
This is a reassuring finding since around 40 percent of women who said they used an antidepressant in early pregnancy were prescribed Zoloft, the researchers point out.
The total increased risk of the rare birth defects seen in the study remains extremely low even with antidepressants, the CDC says.
Other experts said the study should help to reassure women who are pregnant.
"Pregnancy itself predisposes women to become depressed," says Dr. Cynthia Gyamfi-Bannerman of Columbia University Medical College. "For most women it turns out the risk of taking the medication is much lower than the benefits to both them and the developing baby."
The study's findings should help health care providers and women seeking the safest options for treating depression during pregnancy, while still minimizing risks of birth defects in the developing baby, the CDC says.