OBJECTIVE: To examine associations between prenatal exposure to selective serotonin reuptake inhibitors (SSRIs)/anxiolytics and intelligence assessed with a standard clinical intelligence test at age 5 years.

DESIGN: Longitudinal follow-up study.

SETTING: Denmark, 2003-2008.

POPULATION/SAMPLE: A total of 1780 women and their children sampled from the Danish National Birth Cohort.

METHODS: Self-reported information on use of SSRI and anxiolytics was obtained from the Danish National Birth Cohort at the time of consent and from two prenatal interviews. Intelligence was assessed at age 5 years, and parental education, maternal intelligence quotient (IQ), maternal smoking and alcohol consumption in pregnancy, the child's age at testing, sex, and tester were included in the full model. The IQ of 13 medication-exposed children was compared with the IQ of 19 children whose mothers had untreated depression and 1748 control children.

MAIN OUTCOME MEASURE: Wechsler Preschool and Primary Scale of Intelligence - Revised.

RESULTS: In unadjusted analyses, children of mothers who used antidepressants or anxiolytics during pregnancy had higher verbal IQ; this association, however, was insignificant after adjustment for potentially confounding maternal and child factors.

CONCLUSION: No consistent associations between IQ and fetal exposure to antidepressants and anxiolytics were observed, but the study had low statistical power, and there is an obvious need to conduct long-term follow-up studies with comprehensive cognitive assessment and sufficiently large samples of adolescent or adult offspring.