Prevalence of attention‐deficit/hyperactivity disorder and autism in 12‐year‐old children: A population‐based cohort.

Aim: To investigate the prevalence of attention‐deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) in a population‐based birth cohort and correlate the findings with prenatal and perinatal factors. We hypothesized that children born preterm, having experienced preeclampsia or maternal overweight, would have an increased risk of ADHD or ASD. Method: A Swedish cohort of 2666 children (1350 males, 1316 females) has been followed from birth with parental and perinatal data. The National Board of Health and Welfare's registries were used to collect data regarding perinatal status and assigned diagnoses at the age of 12 years. Results: The prevalence of ADHD and ASD was 7.6% and 1.1% respectively. Maternal obesity early in pregnancy resulted in a three‐fold increased risk of ADHD in the child. Similarly, paternal obesity resulted in a two‐fold increased risk. The association was significant also when adjusted for sex, preterm birth, smoking, and lower educational level. The prevalence of ASD was too low for statistically relevant risk factor analyses. Interpretation: Our results corroborate earlier findings regarding prevalence and sex ratio for both ADHD and ASD. Maternal body mass index and preterm birth were correlated with an ADHD diagnosis at the age of 12 years. [ABSTRACT FROM AUTHOR]