Rationale: Use of antidepressants during pregnancy has been associated with an increased rate of children small for gestational age (SGA), but it is unclear whether this is due to an effect of the underlying depressive disorder.
Objectives: This study aimed to investigate the effect of antidepressants on SGA in a nationwide sample and to separate the effect of exposure to antidepressants in utero from the effect of maternal depression.
Methods: A register study was conducted on all pregnant women in Denmark from 1996 to 2006 linking nationwide individualized data from the Medical Birth Register, the Psychiatric Central Register, and a prescription database. The rate of SGA (birth weight below the 10 percentile at given gestational week) was investigated for children exposed in utero to antidepressants or to a maternal psychiatric diagnosis of depression compared to children not prenatally exposed to antidepressants or maternal diagnosis.
Results: A total of 673,853 pregnancies were included in the study of which 35.737 women had a diagnosis of depression and/or used antidepressants before end of pregnancy. Antidepressant use during pregnancy was weakly associated with SGA (hazard ratios (HR) = 1.19; 95 % confidence interval (CI), 1.11-1.28), whereas a psychiatric diagnosis before or during pregnancy was not (HR = 1.02; 95 % CI, 0.92-1.13). The association for use during pregnancy was found for selective serotonin reuptake inhibitors and newer antidepressants, but not for older antidepressants.
Conclusions: The use of antidepressants during pregnancy slightly increases the rate of SGA. The association seems unrelated to the underlying maternal depressive disorder.