Early prenatal exposure to pandemic influenza A (H1N1) infection and child psychomotor development at 6 months - A population-based cohort study.

•Psychomotor development in children exposed to pandemic influenza in utero were compared to unexposed children at age 6 mo.•Prenatal influenza exposure in gestational weeks 0-8 was associated with somewhat delayed psychomotor development at 6 months.•Influenza exposure in gestational weeks 0-8 also indicated slightly worse temperament.•Pre-conceptional exposure to pandemic influenza showed similar trends for both outcomes.•No clear associations with gestational influenza were found for exposure after 9th gestational week.