The relationship between mode of delivery and Attention Deficit Hyperactivity Disorder: a meta-analysis and systematic review

TL;DR

This study finds a moderate link between C-section births and increased ADHD risk in children, based on a review of global research.

Contribution

A meta-analysis combining cohort and case-control studies to assess C-section's association with ADHD risk.

Findings

C-section delivery is associated with a moderately increased risk of ADHD (OR 1.44 in case-control, 1.12 in cohort studies).

Both elective and emergency C-sections showed similar ADHD risk associations.

Study quality was high (NOS score ≥ 7), but heterogeneity and publication bias remain concerns.

Abstract

Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent neurodevelopmental disorder in children, with an etiology that remains incompletely understood. Recent studies have suggested that the mode of delivery, particularly cesarean section (C-section), may be associated with an increased risk of ADHD. This study aims to examine whether children born via C-section are at increased risk of developing ADHD using both cohort and case-control data.

We included observational studies (case-control or cohort) that examined the association between mode of delivery and ADHD in children. Inclusion criteria were: (a) ADHD diagnosed using standardized tools; (b) assessment of the relationship between C-section and ADHD; (c) availability of effect estimates (ORs with 95% CIs). Exclusion criteria were: (a) duplicate or overlapping data; (b) unavailable full text; (c) no extractable effect estimates. Literature searches were conducted in PubMed, Web of Science, CNKI, Wanfang, and VIP. Data were extracted using Excel and analyzed in R Studio with the meta, metabias, and metainf packages to pool the adjusted odds ratios (ORs) for the association between C-section and the occurrence of ADHD. Study quality was assessed using the Newcastle-Ottawa Scale (NOS).

A total of 14 studies were included, consisting of six case-control and eight cohort studies across 10 countries in Asia, Europe, the Americas, and Australia. ADHD diagnoses were based on DSM-IV or ICD-10. Most studies adjusted for key confounders such as maternal age (57.14%), child’s sex (50.00%), and gestational factors (35.71%). The pooled ORs were 1.44 (95% CI [1.04–1.25]) for case-control studies and 1.12 (95% CI [1.10–1.15]) for cohort studies. All studies scored ≥ 7 on the NOS.

This meta-analysis suggests that C-section is associated with a moderately increased risk of ADHD in children. Both elective and emergency C-sections showed similar effects. However, limitations such as study heterogeneity, potential publication bias, and lack of genetic or biological mechanism data are to be acknowledged. Further research is needed to clarify causality and explore underlying mechanisms.

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