Antidepressants while pregnant may cause pre-term, underweight babies

TORONTO (CP) - Taking certain antidepressants during pregnancy may increase the risk of premature delivery, underweight babies, stillbirths and seizures in newborns, a Canadian study suggests.

The study led by researchers at the Ottawa Health Research Institute found pregnant women who took Prozac, Paxil, Zoloft and other selective serotonin re-uptake inhibitors, or SSRIs, had a higher incidence of adverse birth outcomes compared with women who weren't taking the popular drugs while pregnant.

But Dr. Mark Walker, a high-risk obstetrician and senior author of the study, stressed that the researchers found only a correlation, not proof that the antidepressants caused the abnormalities.

Furthermore, some obstetrical experts say it may be the depression itself - and not the drugs - that leads to the problems, and going off the drugs during pregnancy could be dangerous for both a woman and her baby.

Using 1990-2000 health records from Saskatchewan, Walker's team compared 972 pregnant women taking SSRIs and a control group of almost 3,900 women who were not on the medications during pregnancy. Women in the two groups were matched for age, the type of hospital where they gave birth, socioeconomic status based on postal code area and other factors.

"I was surprised at the degree of effect we found," Walker said from Ottawa. "We found there was almost a doubling in the increase" of low birth-weight infants - nine per cent in the SSRI group versus five per cent in the control group.

"Women on SSRIs were more likely to have a pre-term birth - almost 20 per cent versus 12 per cent in our control group," he said. "Fetal death - that's stillbirth - was more common, about two times more common," at one per cent in the drug group versus 0.4 per cent among controls.

Seizures - thought to be one symptom of a newborn's withdrawal from SSRI exposure - during the 48 hours after birth were almost four times more common in the offspring of women who had taken the drugs, Walker said.

"What we cannot determine is (whether) it's the fact that these women are depressed and perhaps have other medical problems or is it the SSRIs," he said, noting that the study tried to adjust for such factors as low socioeconomic status and drug abuse by some women.

"But what we do know is that this group of women are at higher risk for these outcomes and they do need to be followed more carefully and have increased surveillance in their pregnancies.

"Every patient should talk to their doctor about their medication and the safety of staying on them," said Walker, whose study is published in the April issue of the American Journal of Obstetrics and Gynecology.

Dr. Gideon Koren, head of the Motherisk Program at Toronto's Hospital for Sick Children, is critical of the researchers' interpretation, saying that scores of studies show that women with depression during pregnancy have higher risks for underweight newborns, premature delivery and other problems - whether they are taking SSRIs, other antidepressants or none at all.

"Women with depression, because of the depression, are not proactive about their health, they are not going to (doctors') appointments, they are not eating well, they don't have an appetite, they tend to smoke more," Koren, a pediatrician and pharmacologist, said Wednesday.

"And then at the end there is now more and more compelling research that the stress associated with psychiatric morbidity has detrimental effects on the fetus."

Dr. Shaila Misri, a professor of psychiatry, obstetrics and gynecology at the University of British Columbia, agreed, saying that women who are seriously depressed but not treated show altered chemistry in their bodies - "in which the baby is growing for the next 40 weeks."

"And those who don't go on treatment, we are concerned about how lack of treatment and change in their biochemistry will affect them and the babies," Misri, author of the book Pregnancy Blues, said from Vancouver.

Referring to one patient who has been on Paxil throughout her pregnancy, Misri asked: "Do you think she wants to be? Do you think I want to put her on it? No. But she didn't have a choice because her illness and her symptoms outweigh the risks of her taking it."

Koren worries that data from the study could be misinterpreted by pregnant women suffering from depression, who could stop their medication for fear they are trading their babies' health for their own mental well-being.

"The danger is tremendous . . . untreated depression in late pregnancy is the best predictor of postpartum depression, with its huge risk for the life of the woman and for the baby." (Untreated depression could lead to psychosis and/or suicide in some women.)

Dr. Christina Chambers, a specialist in pediatrics and preventive medicine at the University of California at San Diego, said the study's findings of neonatal complications are similar to those from several other SSRI studies. Research she published in February suggests a possible link between moms-to-be taking the drugs and a serious lung problem in infants. Another study found an increased risk of heart defects related to Paxil.

Chambers said scientists are still trying to tease out the actual cause-effect relationship to SSRIs. Confounding issues include, for instance, the fact that depressed women tend to smoke - and tobacco use can cause pre-term and underweight infants.

"It's easy for someone to hear negative information about a drug in pregnancy and think, 'Oh my gosh, I've got to quit it right away,' and that can be not a good thing to do," she said.

"Our position has always been that it's better for people to know what they're up against and if there is a risk associated with it, how big is the risk and is it something that's manageable?

"Obviously, women shouldn't be making the decision independently that they're going to go off the drug without discussing it with their health provider."

© The Canadian Press, 2006