Cesarean delivery and overweight at 6 years of age: a prospective cohort analysis of the Japan Environment and Children's Study.

Cesarean delivery (CD) has been suggested as a potential risk factor for childhood overweight and obesity; however, evidence beyond early childhood remains inconsistent. We examined the association between CD and childhood overweight at age 6 years and explored early life body mass index patterns including adiposity rebound (AR), in a large Japanese birth cohort. We analyzed 64,281 singleton mother-child pairs from the Japan Environment and Children's Study. Overweight at age 6 years was defined according to the International Obesity Task Force criteria. Logistic regression models were used to estimate adjusted odds ratios (aORs). Changes in overweight status between ages 3 and 6 years were examined to distinguish incident overweight from persistent overweight, and AR timing was evaluated. CD accounted for 18.5% of the births. Overweight at age 6 years was more frequent among children born by CD than among those born by vaginal delivery (10.7% vs. 8.8%). After adjusting for the prespecified covariates, CD was associated with higher odds of overweight at age 6 years (aOR 1.09, 95% confidence interval 1.02-1.16). In sex-stratified analyses, CD was associated with incident overweight between ages 3 and 6 years among females but not among males; however, the interaction between delivery mode and sex was not statistically significant. CD was not significantly associated with earlier AR.

Conclusion

In this large Japanese cohort, CD was modestly associated with childhood overweight at age 6 years.