Delivery by caesarean section and risk of obesity in preschool age children: a prospective cohort study.

OBJECTIVE: To examine whether delivery by caesarean section is a risk factor for childhood obesity.

DESIGN: Prospective prebirth cohort study (Project Viva).

SETTING: Eight outpatient multi-specialty practices based in the Boston, Massachusetts area.

PARTICIPANTS: We recruited women during early pregnancy between 1999 and 2002, and followed their children after birth. We included 1255 children with body composition measured at 3 years of age.

MAIN OUTCOME MEASURES: BMI score, obesity (BMI for age and sex ≥95th percentile), and sum of triceps plus subscapular skinfold thicknesses at 3 years of age.

RESULTS: 284 children (22.6%) were delivered by caesarean section. At age 3, 15.7% of children delivered by caesarean section were obese compared with 7.5% of children born vaginally. In multivariable logistic and linear regression models adjusting for maternal prepregnancy BMI, birth weight, and other covariates, birth by caesarean section was associated with a higher odds of obesity at age 3 (OR 2.10, 95% CI 1.36 to 3.23), higher mean BMI z-score (0.20 units, 95% CI 0.07 to 0.33), and higher sum of triceps plus subscapular skinfold thicknesses (0.94 mm, 95% CI 0.36 to 1.51).

CONCLUSIONS: Infants delivered by caesarean section may be at increased risk of childhood obesity. Further studies are needed to confirm our findings and to explore mechanisms underlying this association.