NEW ORLEANS (FRONTLINE MEDICAL NEWS) – Maternal obesity and cesarean delivery were each independently associated with increased rates of overweight or obesity during childhood in a prospective study of 1,441 mothers and their children.

In addition, these risks for childhood obesity appeared to interact in an additive way, so that women who were both obese and delivered by C-section had a nearly threefold increased rate of having a child who was overweight or obese at about 5 years of age, compared with children born to normal-weight women who delivered vaginally, Noel T. Mueller, PhD , said at the American Heart Association Scientific Sessions.

“Decreasing medically unnecessary C-sections may help reduce the intergenerational transmission of obesity,” suggested Dr. Mueller, an epidemiologist at the Johns Hopkins School of Public Health in Baltimore. “Studies are needed to explore mechanisms and to evaluate whether vaginal seeding may help reduce the risk of obesity” in children born by C-section, he added.

This finding of a link between maternal overweight and obesity and childhood obesity in the next generation supports results from previously reported studies. The new results “also add to the growing evidence for an association between C-section and obesity [in offspring], as well as C-section and immune-related disorders such as asthma and allergies” in offspring, Dr. Mueller said in an interview.

He hypothesized that delivery mode may contribute to a child’s obesity risk by producing an abnormal gastrointestinal microbiome. For example, vaginal delivery seems to associate with a higher prevalence of Bacteroides species in a child’s gut, bacteria that aid in the digestion of breast milk, Dr. Mueller said.

His study used data collected in the Boston Birth Cohort from 1,441 mothers and their children from full-term, singleton pregnancies born to women with a body mass index of at least 18.5 kg/m2 during 1998-2014. The child’s weight was measured at a median age of 4.8 years, with an interquartile range of 3-6 years. Children were deemed overweight if they were at or above the 85th percentile for weight, according to standards from the Centers for Disease Control and Prevention.

Just under half the women were normal weight, slightly more than a quarter were overweight, and a quarter were obese. The incidence of 5-year-old children who were overweight or obese was 70% higher in children of overweight mothers and 80% higher in those with obese mothers, compared with children with normal-weight mothers in an analysis that adjusted for maternal age at delivery, race or ethnicity, and education. Both were statistically significant differences, Dr. Mueller reported .

Two-thirds of the women had vaginal deliveries and a third had C-sections. Overweight or obesity occurred in 40% more of the children delivered by C-section, compared with children born vaginally, a statistically significant difference in an analysis that controlled for the same three covariates as well as prepregnancy body mass index, pregnancy weight gain, and other variables.

When Dr. Mueller and his associates ran a combined analysis they found that the highest risk for childhood overweight or obesity was in children born to obese mothers by C-section, and it was a 2.8-fold higher rate than that in the children born to normal-weight mothers by vaginal delivery, a statistically significant difference.

Dr. Mueller had no disclosures.

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