TORONTO - The babies of women who took a common antidepressant in early pregnancy do not appear to have an increased risk of heart defects, a Canadian-led study has found.
Altogether, the outcomes of 1,174 infants in Canada and centres in seven other countries were assessed in the study looking at the drug Paxil, conducted by the Motherisk program at the Hospital for Sick Children and the University of Toronto.
"This drug does not increase the risk of cardiovascular defects, heart defects," lead author Adrienne Einarson said in an interview after the findings were published online this week in the American Journal of Psychiatry.
Data from women and babies who took the drug was compared with the outcomes of women whose infants were not exposed, and the rate of cardiovascular defects was 0.7 per cent in each group.
The incidence of heart defects in the general population is about one per cent.
Einarson began the study after GlaxoSmithKline, the maker of Paxil, published information on its website in 2005 comparing its drug to another antidepressant.
The study based on the outcomes of 815 infants indicated an incidence of cardiovascular malformations of two per cent among the babies of women who had used Paxil. Two other small studies showed rates of two per cent and 1.9 per cent.
Einarson indicated that "based on this rather preliminary information" regulatory authorities in Canada and the U.S. advised women to avoid the drug if possible during pregnancy.
"So everyone got in a panic," she said, noting that the incidence for the GlaxoSmithKline study was later adjusted downward to 1.5 per cent.
Motherisk had calls from women who were already taking Paxil when they found out they were pregnant, and it prompted this new study.
"We know that 50 per cent of pregnancies are unplanned, so if you've already taken it and you're six weeks pregnant, I can tell you also that the heart is one of the first organs to develop. Right after the woman misses her period," she explained.
"By the time they're six weeks pregnant, it's not really much point stopping it anyway, right. It's like closing the barn after the horse is gone."
"The heart is already developed then, so if there was going to be any problem - not that we ever felt there was - but if there was, to tell somebody at that point you should stop taking it, it's not going to be helpful."
The study notes that untreated depression in pregnancy is associated with a sixfold increase in the risk of postpartum depression.
