Main findings
This study reports no substantial risk for ADHD with prenatal SSRI/SNRI
antidepressant exposure at different timings during pregnancy, and no
definite duration-response associations when the hazard of ADHD is
averaged over the study’s follow-up. Misclassification of exposure could
underestimate of about 10% the observed point estimates, leading to an
unaltered inference. When splitting the follow-up time, we observed that
at pre- and early school-age children prenatally exposed to SSRI/SNRI
have lower risk for ADHD diagnosis and symptoms than unexposed. At age
7-9 years, prenatal SSRI/SNRI exposure was associated with greater ADHD
risk in offspring, and this seemed to be mainly driven by longer
duration of SSRI/SNRI exposure. After taking into account biases and
confounding, our best estimate for the weighted HR was around 1.58-1.93
for ever in-utero exposure to SSRI/SNRI, and 2.22-2.76 for 9-20 weeks
duration. Nevertheless, we also document that maternal psychiatric
illness during and prior to during pregnancy are possibly key factors of
joined confounding, yielding substantial risk attenuation to the effect
estimates for SSRI/SNRI in-utero exposure.