Background By 2020, it is predicted that 60 million children worldwide will be overweight. Maternal smoking in pregnancy has been suggested as a contributing factor. Our objective was to systematically review studies on this, thereby expanding the evidence base for this association.
Methods Systematic review with meta-analysis, Prospero Registration number CRD42012002859. We searched PubMed, Embase, Global Health, Web of Science and the Grey literature. We included prevalence, cohort and cross-sectional studies involving full-term, singleton pregnancies. Published and unpublished studies through to 1 January 2015 in all languages, demonstrating an objective overweight outcome up until 18 years of age and data presented as an OR, were included. Quality assessment was undertaken using an adaption of the Newcastle-Ottawa scale. Statistical analysis was performed using Review Manager V.5.3.
Findings The meta-analysis included 39 studies of 236 687 children from Europe, Australia, North America and South America and Asia. Maternal smoking in pregnancy ranged from 5.5% to 38.7%, with the prevalence of overweight from 6.3% to 32.1% and obesity from 2.6% to 17%. Pooled adjusted ORs demonstrated an elevated odds of maternal smoking in pregnancy for childhood overweight (OR 1.37, 95% CI 1.28 to 1.46, I2 45%) and childhood obesity (OR 1.55, 95% CI 1.40 to 1.73, I2 24%).
Interpretation Our results demonstrate an association between maternal prenatal smoking and childhood overweight. This contributes to the growing evidence for the aetiology of childhood overweight, providing important information for policymakers and health professionals alike in planning cessation programmes or antismoking interventions for pregnant female smokers.
- CHILD HEALTH
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Contributors SR devised the study, established inclusion criteria, did all searches of published and unpublished work, evaluated each article for possible inclusion, completed data extraction and quality assessment of each included study, contacted authors of relevant studies, was responsible for statistical analysis and interpretation of the data and drafted the manuscript. EP established inclusion criteria, provided supervision, evaluated each article for possible inclusion, completed data extraction and quality assessment of each included study and assisted with interpretation of the data and critical revision of the manuscript.
Funding SR is a Public Health trainee salaried by Oxford University Hospitals NHS Trust. EP is salaried by the Nuffield Department of Medicine, University of Oxford.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement This study is a systematic review, and all included studies are available.