The Contributions of delivery mode and intrapartum antibiotic exposure to body mass index among children through 5 years of age

Objective

To investigate independent effects of group B Streptococcus (GBS) intrapartum antibiotic prophylaxis (IAP) and cesarean delivery (CD) on body mass index (BMI) during early childhood.

Study design

Retrospective cohort study of infants (n = 157,820) born 2007–2015 in an integrated healthcare system. Exposures were delivery mode (CD or vaginal delivery [VD]) and GBS IAP exposure. CD was further divided into elective CD (without labor or rupture of membrane [ROM]) or unscheduled CD (following labor and/or ROM). BMI over 5 years was compared using non-linear multivariate models with B-splines, adjusted for demographics, maternal medical and obstetrical factors, and childhood antibiotic exposure.

Results

At age 5 years, unscheduled CD without GBS IAP (Δ BMI 0.11 kg/m², 95 % CI 0.06 to 0.16, p < 0.0001) and unscheduled CD with GBS IAP (Δ BMI 0.24 kg/m², 95 % CI 0.11 to 0.36 kg/m², p = 0.0002) were positively associated with higher BMI compared to their VD counterparts, respectively. No BMI difference was observed between children born by elective versus unscheduled CD. GBS IAP exposure was positively associated with increased BMI compared to non-exposed births in both VD (Δ BMI 0.07 kg/m², 95 % CI 0.02 to 0.13 kg/m², p = 0.0125) and CD (Δ BMI 0.22 kg/m², 95 % CI 0.09 to 0.35 kg/m², p = 0.0009).

Conclusions

Based on our findings, the widespread administration of GBS IAP and birth by cesarean delivery independently contribute to a significant upshift in body weight early in life that compares to or is higher than the annual increase in BMI in U.S. children on a population level.