Depression drugs pose fetal risks


Pregnant women with a history of depression now have one more thing to talk to their doctors about.

A new Canadian study suggests the use of popular antidepressants such as Prozac, Paxil and Zoloft during pregnancy might be linked to premature birth, low birth weight babies, infant seizures and a slight increase in fetal death.

But doctors warn the research doesn’t conclude if the use of these antidepressants known as selective serotonin reuptake inhibitors (SSRIs) causes the problems, or if it’s the depression itself affecting the babies.

Led by Dr. Mark Walker, a high-risk obstetrician at The Ottawa Hospital, the study examined the pregnancy outcomes for 972 women who had been given at least one antidepressant, such as fluoxetine (Prozac) paroxetine (Paxil) and sertraline (Zoloft), in the year prior to delivery. The mothers were matched against a control group of pregnant women who had not taken such drugs.

The study found that of women on the antidepressants, 19.3 per cent gave birth to pre-term babies, compared with 12 per cent of women not on the drugs. Almost 9 per cent of babies born to women on the drugs were low birth weight, defined as less than 2,500 grams (or 5 1/2 pounds), compared with 5.3 per cent of women not on antidepressants. Fetal death occurred in 1.1 per cent of the mothers on antidepressants compared with 0.4 per cent.

“You are getting close to one-third of these pregnancies being affected by major complication,” Walker said. “The magnitude was a surprise.”

But Walker stressed depressed women who are on SSRIs must talk with their doctors before either coming off SSRIs or continuing treatment. “For any woman I treat on SSRIs, I would review the indication for the medication, her mental status at the time, her mental history, to see if it can be safely stopped. If not, then continue the patient on,” he said.

The Ottawa team found no greater risk of birth defects, infection, need for breathing support or death up to one year after birth.

While previous studies have reported side effects of SSRIs on the fetus, this investigation says it is the largest looking at a wide variety of side effects without relying on patient memory for prescription records.

Dr. Robert Swenson of The Ottawa Hospital said this study shouldn’t frighten depressed women off their medication. Not treating depression can put women at risk of suicide, lack of self-care during pregnancy and inability to care for their baby.

A woman who suffers depression when expecting is at far greater risk of postpartum depression once the baby is born. Stopping the drugs could put mom and baby in harms way.

“The study can’t determine if it’s drug related or a result of the illness,” he said. “You don’t want to scare women who may need medication to help them.”

The study was published today in this month’s issue of the American Journal of Obstetrics and Gynecology. Researchers used data collected from 1990 to 2000 from Saskatchewan Health databases on maternal and infant prescription records. Saskatchewan tracks patient information on prescription drug use.

The study sample size was not large enough to estimate risks for each antidepressant or selective serotonin reuptake inhibitors (SSRIs) individually.

Walker said there are limitations to the study; women on antidepressants were more likely to be on social assistance and to have had drug dependence issues. Drug dependence alone is a significant risk factor for perinatal death, the study said. Variables such as smoking and drinking were not available.

The study can show an association of risks to the fetus, but it can’t prove causation, Walker added.

The research was paid for by a grant from the Hospital for Sick Children, and the Canadian Institutes of Health Research.

In September 2005, the makers of Paxil, GlaxoSmithKline Inc., put out new safety information regarding its use during the first trimester of pregnancy. According to a preliminary report, there appeared to be an increased risk of major congenital malformations, and some cardiovascular malformations.