Use of antidepressants during pregnancy and the risk of spontaneous abortion.

Background: The risk of relapse of depression or the diagnosis of some other psychiatric disorders during pregnancy necessitates the use of antidepressants despite possible adverse effects. Whether such use increases the risk of spontaneous abortion is still being debated. We evaluated the risk of spontaneous abortion in relation to the use of antidepressants during pregnancy.
Methods: Using a nested case-control study design, we obtained data from the Quebec Pregnancy Registry for 5124 women who had a clinically detected spontaneous abortion. For each case, we randomly selected 10 controls from the remaining women in the registry who were matched by the case's index date (date of spontaneous abortion) and gestational age at the time of spontaneous abortion. Use of antidepressants was defined by filled prescriptions and was compared with nonuse. We also studied the classes, types and doses of antidepressants.
Results: A total of 284 (5.5%) of the women who had a spontaneous abortion had at least one prescription for an antidepressant filled during the pregnancy, as compared with 1401 (2.7%) of the matched controls (odds ratio [OR] 2.09, 95% confidence interval [CI] 1.83-2.38). After adjustment for potential confounders, we found that the use of antidepressants during pregnancy was associated with an increased risk of spontaneous abortion (OR 1.68, 95%CI 1.38-2.06). Stratified analyses showed that use of selective serotonin reuptake inhibitors alone (OR 1.61, 95% CI 1.28-2.04), serotonin-norepinephrine reuptake inhibitors alone (OR 2.11, 95% CI 1.34-3.30) and combined use of antidepressants from different classes (OR 3.51, 95% CI 2.20-5.61) were associated with an increased risk of spontaneous abortion. When we looked at antidepressant use by type versus no use, paroxetine use alone (OR 1.75, 95% CI 1.31-2.34) and venlafaxine use alone (OR 2.11, 95% CI 1.34-3.30) were associated with an increased risk of spontaneous abortion.
Interpretation: The use of antidepressants, especially paroxetine, venlafaxine or the combined use of different classes of antidepressants, during pregnancy was associated with an increased risk of spontaneous abortion.