Maternal smoking during pregnancy and offspring obesity: Meta-analysis

Background: Recent reports have suggested that maternal smoking may increase the risk of development of obesity in the unborn child in later life, but relatively few cohort studies have been done on the relationship between maternal smoking during pregnancy and future development of metabolic syndrome. Methods: A systematic review and meta-analysis of observational studies reporting effect estimates and 95% confidence intervals (95%CI) was conducted on the association between maternal smoking during pregnancy and obesity of future offspring. Results: Seventeen papers were identified from 444 English-language papers (key word search: maternal smoking and obesity) in PubMed. All papers showed a positive association between maternal smoking during pregnancy and childhood obesity. The meta-analysis, using the DerSimonian-Laird method, found the association to be statistically significant. In association with maternal smoking during pregnancy and body mass index with more than 95%CI in the offspring aged 3-33 years, the pooled odds ratio calculated from 16 of these 17 studies was 1.64 (95%CI: 1.42-1.90). After adjustment for publication bias, the pooled adjusted odds ratio was 1.52 (95%CI: 1.36-1.70). In addition, confounders of maternal obesity, low social status, low birthweight and not being breast-fed seemed to be risk factors for offspring obesity. Conclusion: Maternal smoking during pregnancy may cause future obesity and metabolic syndrome.