Question: Is prenatal exposure to multiple substances, alone or in combination, associated with the risk of attention-deficit/hyperactivity disorder (ADHD) in childhood?

Findings: In this cohort study of 3138 children with and without ADHD, prenatal opioid exposure was significantly associated with the highest childhood risk of ADHD among all substances measured. Interactions between exposure to opioids and cannabis as well as opioids and alcohol were also associated with ADHD risk.

Meaning: This study’s findings suggest that it is important to consider prenatal exposure to multiple substances and the interactions between these substances when counseling women regarding substance use during pregnancy.

[See also, invited commentary: Polysubstance exposure during pregnancy and attention-deficit/hyperactivity disorder in offspring—methodological challenges and opportunities for future research]