Pre- and perinatal risk factors in adults with attention-deficit/hyperactivity disorder

Biol Psychiatry. 2012 Mar 1;71(5):474-81. doi: 10.1016/j.biopsych.2011.11.013. Epub 2011 Dec 24.


Background: Attention-deficit/hyperactivity disorder (ADHD) is a prevalent and disabling lifespan disorder, but little is yet known about risk factors for ADHD persisting beyond adolescence. The present study investigates the association between pregnancy and birth complications and ADHD in adulthood.

Methods: We used data from the Medical Birth Registry of Norway to compare pre-and perinatal risk factors among 2323 adults approved for medical treatment for ADHD, with the remaining population born during the same years, 1967-1987, and surviving into adulthood (n = 1,170,073). Relative risks (RR) adjusted for potential confounders were calculated.

Results: Preterm (< 37 weeks of gestation) and extremely preterm birth (< 28 weeks of gestation) were associated with 1.3- and 5-fold increased risks of ADHD, respectively. Birth weights <2500 g and <1500 g also increased the risk of ADHD (RR: 1.5, 95% confidence interval [CI]: 1.2-1.8, and RR: 2.1, 95% CI: 1.3-3.6, respectively). Five-minute Apgar scores <4 and <7 were associated with 2.8- and 1.5-fold increased risks of persisting ADHD, respectively. Maternal epilepsy (RR: 1.7, 95% CI: 1.1-2.7) and offspring oral cleft (RR: 2.8, 95% CI: 1.6-4.9) occurred more frequently among adult ADHD patients.

Conclusions: This is the first population-based study of pre-and perinatal risk factors in adults with ADHD. We show that low birth weight, preterm birth, and low Apgar scores increase the risk of ADHD, persisting up to 40 years after birth. The increased risk of ADHD related to oral cleft and to maternal epilepsy warrants further investigation to explore possible causal mechanisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Apgar Score
  • Attention Deficit Disorder with Hyperactivity / epidemiology*
  • Attention Deficit Disorder with Hyperactivity / etiology
  • Birth Weight
  • Congenital Abnormalities / psychology*
  • Female
  • Humans
  • Infant, Low Birth Weight / psychology*
  • Infant, Newborn
  • Infant, Premature / psychology
  • Male
  • Norway
  • Pregnancy
  • Pregnancy Complications / psychology*
  • Registries / statistics & numerical data*
  • Risk Factors