News

Women who take a popular class of antidepressants during pregnancy have a higher risk of birth complications, according to a new Canadian study.

The research shows that women who take selective serotonin reuptake inhibitors - SSRIs, a class of drugs that includes big-selling brand names such as Prozac, Paxil and Zoloft -- are at increased risk of having a fetus who dies, experiencing premature delivery, giving birth to an underweight baby and seeing their newborn have seizures.

Almost one-third of the women taking SSRIs experienced at least one of those complications.

"These results are unsettling," said Mark Walker, a scientist at the Ottawa Health Research Institute and lead author of the study.

He cautioned, however, that women should not necessarily stop taking the drugs, but rather consult with their doctors.

Dr. Walker said the appropriateness of prescribing antidepressants should be determined on a case-by-case basis because depression can also have serious effects on a pregnant woman and her fetus. Women who are depressed sometimes eat poorly or they self-medicate with tobacco, alcohol and non-prescription drugs, all of which can cause far more severe damage to the fetus.

"Patients need to make informed decisions," Dr. Walker said. He added that women taking SSRIs during pregnancy should also be monitored more closely because of the higher risk of complications.

Between 10 and 15 per cent of pregnant women suffer from depression, but it is unclear how many are treated with antidepressants. Dr. Walker said it is probably somewhere between 1 and 5 per cent. That means as many as 17,000 Canadian women could be taking SSRIs during pregnancy each year, a significant number.

In 2004, Health Canada issued an advisory that warned pregnant women to avoid a number of antidepressants, most of them SSRIs.

The regulatory agency said newborns whose mothers took the drugs "can experience drug-withdrawal symptoms or toxicity after delivery." The effects are wide-ranging, though the most common symptoms include respiratory problems, trouble eating, irritability, body rigidity and constant crying. In some cases, Health Canada warned, newborns may require tube feeding or breathing support, but said the symptoms appear to be reversible.

The new study, published in today's edition of the American Journal of Obstetrics and Gynecology, was based on the health records of 972 pregnant women taking SSRIs (and a comparison group of 3,878 new mothers who did not take the drugs). It identified far more serious risks than those in the advisory.

The research showed that almost 20 per cent of women taking SSRIs had a premature birth, compared to 12 per cent for those not taking the prescription antidepressants; 9 per cent had low-birth-weight babies, versus 5.3 per cent for non-takers; and the fetal death rate was 1.1 per cent in the SSRI group, versus 0.4 per cent. The percentage of newborns suffering seizures was 0.4 in the SSRI group, compared to 0.1 per cent. Researchers did not find an increased risk of birth defects, infections or death.

A recent, unrelated study found that children born of mothers taking SSRIs have much higher rates of pulmonary hypertension.