Antidepressant use during the gestational period is a controversial topic.

To determine whether duration of antidepressant use during the first trimester increases the risk of major congenital malformations in offspring of women diagnosed with psychiatric disorders.

A case-control study was performed among women who had been pregnant between January 1998 and December 2002. Data were obtained from a Medication and Pregnancy registry, built by linking three databases from the province of Quebec, and a self-administered questionnaire. Women eligible for this study had to be 15–45 years old at the beginning of pregnancy, have at least one diagnosis of psychiatric disorder before pregnancy, have used antidepressants for ≥ 30 days in the year prior to pregnancy and have a pregnancy ending with a delivery. Cases were defined as any major congenital malformation diagnosed in the offspring's first year of life. Odds ratios, adjusted for relevant confounders, were estimated using logistic regression.

Among the 2329 women meeting the inclusion criteria, 189 (8.1%) infants were born with a major congenital malformation. Duration of antidepressant use during the first trimester of pregnancy was not associated with an increased risk of major congenital malformations: 1–30 days v. 0 day, adjusted OR=1.23 (95% CI 0.77–1.98); 31–60 days v. 0 day, adjusted OR=1.03 (95% CI 0.63–1.69); ≥ 61 days v. 0 day, adjusted OR=0.92 (95% CI 0.50–1.69).

These data do not support an association between duration of antidepressant use during the first trimester of pregnancy and major congenital malformations in the offspring of women with psychiatric disorders. These findings should help clinicians decide whether to continue antidepressant therapy during pregnancy.