C-Section Associated With Increased Risk of Obesity, Type 2 Diabetes

Jorge Chavarro, MD, ScD

A new study has identified a significant association between being born via cesarean delivery and increased risks of obesity and type 2 diabetes in adulthood.

Jorge Chavarro, MD, ScD, and colleagues compared the incidence of obesity and type 2 diabetes between cesarean and vaginal delivery among more than 30,000 women participating in the Nurses’ Health Study II. The study findings suggested that women born by cesarean delivery had a higher risk of developing such conditions during adult life than women born via vaginal delivery.

Chavarro, from the Harvard T.H. Chan School of Public Health, and the team of investigators included 33,226 participants born between 1946-1964. Participants were excluded if they did not provide information on delivery mode and height or weight and were not born of a singleton pregnancy.

Information on height and weight were updated from baseline every 2 years. The investigators calculated body mass index (BMI) from the data. Obesity was defined as a BMI >30 using the World Health Organization (WHO) cutoffs.

Participants reported physician-diagnosed type 2 diabetes on follow-up questionnaires. Cases were confirmed based on American Diabetes Association criteria: >1 classic symptom (excessive thirst; polyuria; weight loss; hunger; pruritus; or coma) plus elevated glucose levels; no symptoms reported but >2 elevated plasma glucose concentrations on >1 occasion; or treatment with insulin or an oral hypoglycemic agent.

The participants’ mean age was 33.8 years old (range, 24-44 years old). Among those included, 3.3% were born by a cesarean delivery. Mothers of those delivered by cesarean section (C-section) had a higher mean prepregnancy BMI than those delivered vaginally (21.7 vs 21.2), were older (mean age at delivery, 28.2 vs 26.2 years old), and were more likely to have preeclampsia (5.0% vs 3.2%), pregnancy-induced hypertension (5.1% vs 3.4%), preterm birth (9.2% vs 4.1%), and low birth weight (8.6% vs 5.9%).

Women who gave birth by C-section were less likely to smoke during pregnancy (22.9% vs 26.1%) and to breastfeed their daughters (32.1% vs 46.1%) than those who had a vaginal delivery.

There were 12,156 cases of obesity and 2014 new cases of type 2 diabetes during nearly 2 million person-years of follow-up. The incidence of diabetes per 10,000 person years was 10.4 among those born vaginally and 14.1 for those born through C-section.

C-section delivery was associated with a higher risk of obesity (RR, 1.09; 95% CI, 1.01-1.18). The incidence of type 2 diabetes was also higher among women born by C-section (HR, 1.42; 95% CI, 1.14-1.76).

The association of C-section delivery with risks of obesity and type 2 diabetes were of comparable magnitude across each low-risk category for such delivery based on maternal characteristics, separately, and when considered together.

Additional research should replicate the association with type 2 diabetes and address the biological mechanisms underlying the link between C-section and increased risk of offspring diabetes and obesity in adulthood.

The study, “Association of Birth by Cesarean Delivery With Obesity and Type 2 Diabetes Among Adult Women,” was published online in JAMA Network Open.