Some Anti-Depressants Linked to Rare Cases of Birth Defects, Study Reveals

— -- A new study has shed light on the complex interaction between anti-depressants and pregnancy by looking at thousands of women who took them before giving birth.

The study published in The BMJ, previously known as the British Medical Journal, found that some popular antidepressants known as SSRIs (selective serotonin reuptake inhibitors)were in rare cases associated with an increased risk in birth defects. However, they found that one drug, commonly sold under the brand name Zoloft, was not associated with any increased risk.

The researchers from the U.S. Centers for Disease Control and Prevention, Boston University and the University of British Columbia studied more than 27,000 women who had children between 1997 to 2009. In spite of the findings the experts strongly cautioned against pregnant women forgoing medication treatment without consulting a doctor due to the risks associated with depression during pregnancy.

Dr. Cynthia Gyamfi-Bannerman, Associate Professor of Obstetrics and Gynecology at Columbia University Medical College, told ABC News women should always consult with their doctors before going off their medication, even if pregnant.

"Pregnancy itself predisposes women to become depressed," said Gyamfi-Bannerman. "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."

A major finding in the study was that the most commonly reported type of SSRI, sertraline, sold most often under the brand name Zoloft was not associated with any of the five birth defects identified in earlier studies. Approximately 40 percent of the women who used SSRI drugs reported using sertraline.

Dr. Bill Cooper, Professor of Pediatrics at Vanderbilt University Medical Center, said these large studies are key to help pregnant women make the best decisions about their health care.

"When you look at sertraline, it’s one of the most commonly used antidepressants," said Cooper. He said the findings that the Zoloft was not associated with any birth defects should be "reassuring" for expectant women.

"Women are very reluctant to take medications at all during pregnancy. Sometimes that makes their condition worse," said Cooper. "It creates more risk for the? developing fetus. You want the best possible information to guide a mother and her physician."

Other antidepressants studied in the research include paroxetine commonly sold under the brand name Paxil and fluoxetine commonly sold under the brand name Prozac. In this study these drugs were found to be significantly associated with various birth defects, but the overall risk remained extremely low.

The more common birth defects associated with anti-depressants include heart defects, issues with the abdominal wall, anus and malformation of the skull and brain.

Eli Lilly, which distributes Prozac, told ABC News its drugs face rigorous safety evaluations before being released and that the company "completed a significant body of research on Prozac, which is considered as having a positive benefit-risk profile for patients by regulatory authorities and physicians around the world."

GlaxoSmithKline, which makes Paxil, said the medication warns doctors to counsel patients about the risks before taking medication.

"It’s very important that physicians advise any women considering use of Paxil (paroxetine) or other SSRIs during pregnancy of the potential risks, which are clearly detailed within the product label and patient information, recognizing that for some the benefits of therapy may continue to outweigh the potential risk," a GlaxoSmithKline spokesman said in a statement. " As with any medicine it is very important that patients do not stop taking their medication without first speaking to their physician.”

Researchers and experts caution that the total increased risk of birth defect remained extremely small and pointed out those taking paroxetine had only a slight risk of having a fetus develop anencephaly, which is malformation of the skull and brain. In paroxetine's case the potential risk went up from two per 10,000 births to seven per 10,000 births. For heart defects the potential risk went from 10 to 24 per 10,000 births.