Use of antidepressants during pregnancy has been associated with a low Apgar score in infants but a contribution from the underlying depressive disorder might influence this association.

To estimate the effects of maternal depression and use of antidepressants during pregnancy on low Apgar scores (<7) 5min after birth.

Register study on all pregnant women in Denmark from 1996 to 2006 linking nationwide individualised data from the Medical Birth Register, the Psychiatric Central Register and the National Prescription database.

Infants exposed to antidepressants during pregnancy had an increased rate of a low Apgar score (odds ratio (OR) = 1.72, 95% CI 1.34-2.20). The increased rate was only found among infants exposed to selective serotonin reuptake inhibitors (SSRIS) (OR =1.96, 95% CI 1.52-2.54), not among those exposed to newer (OR = 0.83, 95% CI 0.40-1.74) or older antidepressants (OR=0.53, 95% CI 0.19-1.45). Maternal depression before or during pregnancy, without prescription of antidepressants, was not associated with a low Apgar score (OR=0.44, 95% CI 0.11-1.74). Women who had only used antidepressants prior to pregnancy had no increased rate of a low Apgar score in their subsequent pregnancy, regardless of depression status.

Use of SSRls during pregnancy increases the risk of a low Apgar score independently of maternal depression.