1245-P: Maternal HbA1c Is Related to Childhood Fat Mass and Only Partially Mediated by Neonatal Fat Mass

Abstract

Maternal diabetes during pregnancy impacts offspring body composition and has been associated with greater offspring adiposity across the life course. However, the extent to which the relationship between maternal glycemia and offspring adiposity during later life is independent of neonatal adiposity is unclear. In a prospective study of 544 mother-child pairs in the Healthy Start Study, we estimated the total effect of maternal HbA1c on childhood fat mass (FM) %, and the direct effect independent of neonatal FM %. We measured maternal fasting HbA1c at a gestational age of 20-34 weeks, and offspring FM % using air displacement plethysmography at birth and during childhood (age 4-7 y). We used multivariable linear regression with HbA1c tertiles (T1 [reference], T2, T3) as the exposure, neonatal FM % as the mediator, and childhood FM % as the outcome. A counterfactual-based approach was used to estimate total and direct effects, while also accounting for exposure-mediator interaction. Covariates were maternal race, education, gestational weight gain and smoking, and offspring sex and age. The medians (interquartile ranges) of the HbA1c tertiles were T1: 4.80 (3.70, 4.90), T2: 5.05 (5.00, 5.10), and T3: 5.30 (5.20, 6.30). The estimated total effect on child FM % was 1.27 (95% CI: 0.00, 2.54) units higher for T2 vs. T1, and 1.53 (0.23, 2.82) units higher for T3 vs. T1 (P-trend=0.02). After adjusting for pre-pregnancy BMI, the total effect was 1.18 (-0.09, 2.44) and 1.31 (0.00, 2.62) units higher for T2 vs. T1 and T3 vs. T1, respectively (P-trend=0.04). The direct effect after accounting for neonatal FM % was slightly attenuated (T2 vs. T1: 1.14 [-0.11, 2.39], T3 vs. T1: 1.20 [-0.11, 2.51]; P-trend=0.07). Excluding women with gestational diabetes mellitus (n=27) did not substantially impact the results. Our data suggest that maternal glycemia during pregnancy, even within normal levels, may influence childhood adiposity through pathways that are in part mediated by programming of neonatal adiposity. Disclosure E.C. Francis: None. B. Ringham: None. D.H. Glueck: None. W. Perng: None. D. Dabelea: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (5R01DK076648-10)