Exploring the association between maternal attention-deficit/hyperactivity disorder and obstetric complications: a danish population-based register study

Purpose: Maternal attention-deficit/hyperactivity disorder (ADHD) is increasingly recognised during the reproductive years, often with delayed diagnosis. Although ADHD has been linked to perinatal complications, it remains unclear whether risks reflect ADHD itself, comorbidity, vulnerability, behaviours, and medication use. We examined associations between maternal ADHD, stratified by diagnosis before and after childbirth, and ADHD medication exposure during pregnancy with a range of pregnancy, childbirth, and neonatal outcomes. Methods: We conducted a nationwide register-based cohort study, including 741,905 singleton live births in Denmark (2010–2022). Childbirths were classified by maternal ADHD diagnosis before childbirth (n = 12,859), after childbirth (n = 15,683), and no ADHD (n = 713,363). Among women diagnosed before childbirth, ADHD medication exposure was classified; no exposure (n = 10,118), first-trimester (n = 1,129) and continued (n = 1,612) based on prescription-timing. Analyses were preformed using Poisson GEE, accounting for repeated births and adjusting for sociodemographics, psychiatric history, and somatic comorbidity. Results: Maternal ADHD diagnosed before childbirth was associated with preterm childbirth (aRR 1.13, 95% CI 1.04–1.22; aRR 1.29, 95% CI 1.07–1.56) and low birthweight (aRR 1.19, 95% CI 1.09–1.30). Early pregnancy haemorrhage was modestly elevated for ADHD diagnosed before and after childbirth (aRR 1.15, 95% CI 1.08–1.25; aRR 1.14, 95% CI 1.07–1.22). ADHD diagnosed after childbirth was associated with infection (aRR 1.19, 95% CI 1.11–1.27), hyperemesis (aRR 1.23, 95% CI 1.13–1.34), and Apgar score < 7) (moderate aRR 1.48, 95% CI 1.09–2.01; severe aRR 1.32, 95% CI 1.09–1.59). ADHD medication in pregnancy (vs. unmedicated) was associated with gestational hypertension (first-trimester aRR 1.57, 95% CI 1.21–2.02; continued aRR 1.39, 95% CI 1.01–1.91). Conclusion: Maternal ADHD, whether diagnosed before childbirth or postpartum, was associated with small increases in selected obstetric and neonatal risks after adjustment for relevant sociodemographic and clinical factors. Continued use of ADHD medication was significantly associated with gestational hypertension only. However, these findings should be interpreted with caution due to the potential for residual confounding, including confounding by indication.