Background: This meta-analysis aimed to evaluate the association between maternal smoking during pregnancy and the risk of Attention-Deficit/Hyperactivity Disorder (ADHD) in offspring. This association is complex and may be influenced by genetic confounding, as individuals with ADHD are at higher risk of engaging in smoking behaviors. Methods: The PubMed, Scopus, Web of Science, and Cochrane Library databases were searched to identify relevant literature. Prospective cohort studies that met the inclusion criteria entered the data extraction process. Selected data for analysis included risk estimates in form of odds ratios (ORs), hazard ratios (HRs), or risk ratios (RRs), along with 95% CIs. Sensitivity and bias analysis were also performed. Results: A total of 14 prospective cohorts comprising 1,763,268 participants were eligible for the analysis. Smoking during pregnancy was associated with an increased risk ADHD in the offspring (pooled RR = 1.55 95% CI: 1.25–1.86, p < 0.001). This association decreased slightly after subgroup analysis based on adjustment for maternal ADHD (RR = 1.47 95% CI: 1.08–2.01, p < 0.001). This observation was replicated after adjustment for study location, maternal age, alcohol consumption, maternal socioeconomic status, and ADHD history. Conclusions: Based on the evidence presented in this systematic review and meta-analysis, maternal smoking during pregnancy is associated with an increased risk of ADHD in offspring. Therefore, pregnant women should be encouraged to quit smoking and to avoid exposure to tobacco smoke. Registration: The study has been registered on https://www.crd.york.ac.uk/PROSPERO/search (registration number: CRD420251274456; registration link: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251274456).
Zakerinasab et al. (Tue,) studied this question.