Children born to mothers with severe obesity were more likely to be admitted to the hospital for infections during childhood and adolescence compared with those who were born to mothers with a healthy body mass index, according to a UK cohort study.
In infancy, these children had about 41% more admissions. During follow-up, 30% of children had at least one hospital admission for infection and the highest rates occurred in the first year of life. By ages 5 to 15 years, the excess risk rose to about 53%. Respiratory and gastrointestinal infections, as well as multisystem viral infections, accounted for most of the excess admissions.
Similar patterns were observed for both upper and lower respiratory tract infections, but after adjusting for socioeconomic factors and ethnic group, the researchers found that grade 2 to 3 obesity was no longer significantly associated with increased rates of admissions for lower respiratory tract infections. Mediation analysis suggested that being born by cesarean section accounted for about 21% of the association between severe maternal obesity and childhood infection admissions, while childhood obesity at ages 4 to 5 years accounted for about 26%, and preterm birth explained about 7%. Breastfeeding and gestational weight gain did not appear to have a significant mediating effect. "The absence of mediation from breastfeeding was surprising given that breastfeeding has a well established protective effect against childhood infections," the authors noted.
Lead author Victoria Coathup, PhD, of the National Perinatal Epidemiology Unit, Nuffield Department of Population Health at the University of Oxford, suggested with coauthors that "many factors, such as inflammatory processes, epigenetic changes, metabolic dysregulation, and alterations to the microbiome, could influence the developing immune system, thus contributing to increased vulnerability to infections during childhood."
The study analyzed data from 9,540 singleton births between 2007 and 2011 from the Born in Bradford cohort, including 9,037 mothers. Participants were followed from birth until about age 15 years using linked hospital records. Maternal body mass index (BMI) was measured during the first trimester and categorized as underweight, healthy weight, overweight, obesity grade 1, and obesity grades 2 to 3. More than half of mothers (56%) were overweight or obese during early pregnancy, and 10% had obesity grades 2 to 3 (BMI of at least 35).
Limitations included reliance on data from a single hospital, which may have missed admissions elsewhere, and the exclusion of milder infections that did not require hospitalization. Recording maternal BMI in the first trimester may have led to some misclassification. Missing data for breastfeeding and child BMI mean that mediation results should be interpreted with caution, the authors noted. The study also lacked information on diet, physical activity, or paternal BMI, which limited adjustment for some lifestyle confounders.
The researchers concluded that while the effect was modest and limited to mothers with the highest BMI category, the potential population impact is considerable given the rising global prevalence of obesity. They noted that mode of birth and early-life obesity may be intervention points to help reduce infection-related hospital admissions in children.
Full disclosures can be found in the published study.
Source: BMJ Medicine