New journal article which uses Young Lives data from the public archive, written by Rodrigo M. Carrillo-Larco, Antonio Bernabé-Ortiz (from CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima) and J. Jaime Miranda (Department of Medicine, Universidad Peruana Cayetano Heredia, Lima)

Objectives. We aimed to assess if Caesarean section is a risk factor for overnutrition in early- and late-childhood, and to assess the magnitude of the effect of child- versus family-related variables in these risk estimates.

Methods. Longitudinal data from Peruvian children from the Young Lives Study was used. Outcomes assessed were overweight, obesity, overnutrition (overweight plus obesity), and central obesity (waist circumference) at the age 5 (first follow-up) and 7 (second follow-up) years. The exposure of interests was delivery by Caesarean section. Relative risks (RR) and 95% confidence intervals (95% CI) were calculated using multivariable models adjusted for child-related (e.g., birth weight) and family-related (e.g., maternal nutritional status) variables.

Results. At baseline, mean age was 11.7 (± 3.5) months and 50.1% were boys. Children born by Caesarean section were 15.6%. The 10.5% of the children were overweight and 2.4% were obese. For the obesity outcome, data from 6,038 and 9,625 children-years was included from baseline to the first and second follow-up, respectively. Compared to those who did not experience Caesarean delivery, the risk of having obesity was higher in the group born by Caesarean: RRs were higher at early-childhood (first follow-up: 2.25; 95% CI [1.36?3.74]) than later in life (second follow-up: 1.57; 95% CI [1.02?2.41]). Family-related variables had a greater effect in attenuating the risk estimates for obesity at the first, than at the second follow-up.

Conclusion. Our results suggest a higher probability of developing obesity, but not overweight, among children born by Caesarean section delivery. The magnitude of risk estimates decreased over time, and family-related variables had a stronger effect on the risk estimates at early-childhood.

Rodrigo M. Carrillo-Larco, J. Jaime Miranda and Antonio Bernabé-Ortiz (2015) Delivery by Caesarean Section and Risk of Childhood Obesity: Analysis of a Peruvian Prospective Cohort, PeerJ 3: e1046.