In utero exposure to antidepressant drugs and risk of attention deficit hyperactivity disorder: a nationwide Danish cohort study.
OBJECTIVE
To investigate whether in utero exposure to antidepressants is associated with increased risk of attention deficit hyperactivity disorder (ADHD).


METHODS
Cohort study.


METHODS
Denmark.


METHODS
All Danish singletons born alive from 1996 to 2009 were included. Using national medical registries, we defined in utero exposure to antidepressants as redemption of an antidepressant prescription by the mother 30 days prior to or during pregnancy. We defined maternal former users of antidepressants as women, who had redeemed a prescription up to 30 days prior to pregnancy, and never users as women who had never redeemed a prescription.


METHODS
ADHD was defined as redemption of a prescription for ADHD medication or an ADHD hospital diagnosis. Children were followed through 2010, and we used proportional-hazards regression to compute adjusted HRs comparing children exposed in utero and children born to former antidepressant users with children born to never users. To adjust for confounding from family-related factors, we conducted a within-mother between-pregnancy analysis comparing exposed children with unexposed siblings using conditional logistic regression.


RESULTS
We identified a cohort of 877 778 children, of whom 1.7% were exposed in utero. The overall median follow-up time was 8 years; selective serotonin reuptake inhibitors were the most commonly used class of antidepressant during pregnancy (78% of users). The adjusted HR comparing children exposed to any antidepressant in utero with children born to never users was 1.2 (95% CI 1.1 to 1.4), and 1.6 (95% CI 1.5 to 1.8) comparing children born to former users to children born to never users of antidepressants. In the within-mother between-pregnancy analysis (n=867), the adjusted OR was 0.7 (95% CI 0.4 to 1.4).


CONCLUSIONS
This study provides no evidence to support a causal association between in utero exposure to antidepressants and risk of ADHD.
Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
Kristina
K
Laugesen
Morten Smærup
MS
Olsen
Ane Birgitte
AB
Telén Andersen
Trine
T
Frøslev
Henrik Toft
HT
Sørensen