Xu Ll, et al. - Since epidemiological studies on correlations between caesarean sections (C-sections) and attention-deficit hyperactivity disorder (ADHD) were inconsistent, researchers carried out a systematic literature review and meta-analysis to explore any link between C-sections and the subsequent development of ADHD in offspring. PubMed and Embase were systematically searched to December 2018 and involved nine hospital-based and population registry studies published in 2011-2018. These included a total study cohort of more than 2.5 million individuals in eight countries: Australia, Brazil, Denmark, Finland, Germany, Sweden, Turkey and the UK. Findings suggested an association of C-sections with a small increase in the risk of ADHD in offspring. The connection persisted for both infants born after elective C-sections and emergency C-sections in subgroup analyses. However, when the authors pooled data from siblings from other pregnancies, these were only slightly significant, suggesting that the correlation was attributable to uncertainty. Unmeasured confounding can partially explain the statistically significant correlation between C-sections and ADHD in children. Until firm conclusions can be drawn, more work controlling important confounders is needed.