“…The rst stage exact-and propensity-matching by mother's year of birth, child's gender, child's year of birth, and child's rst use of health insurance card (all p > 0.99 after exact matching) of mothers exposed to substances before pregnancy (n = 1776, the 'substance-exposed before pregnancy cohort'), mothers exposed to substances during pregnancy (n = 1776, the 'substance-exposed during pregnancy cohort'), and the comparison cohort ('substance-unexposed mothers', n = 3552). More details may be referred to our previous work(Lee et al, 2023).ADHD: Attention de cit and hyperactivity disorderThe comparison cohort was selected by two-stages of exact-and propensity score (PS) matching. The rst stage exact-and propensity-matching by mother's year of birth, child's gender, child's year of birth, and child's rst use of health insurance card (all p > 0.99 after exact matching) of mothers exposed to substances before pregnancy (n = 1776, the 'substance-exposed before pregnancy cohort'), mothers exposed to substances during pregnancy (n = 1776, the 'substance-exposed during pregnancy cohort'), and the comparison cohort ('substance-unexposed mothers', n = 3552).…”