OBJECTIVE: This study sought to evaluate the distinct impact of fetal exposure to gestational diabetes (GDM) severity, as well as the impact of infant breastfeeding (BF) and sugary beverage intake, on preadolescent overweight and obesity, accounting for other established risk factors. METHODS: This analysis included 850 mother-infant dyads exposed to GDM who reported monthly infant BF duration and intensity, as well as sugary beverage intake (sugar-sweetened beverages [SSB] and 100% fruit juice [FJ]) during the first year of life, BMI measured at ages 6 to 11 years, and GDM severity variables (i.e., diagnosis time, treatment, and glycemic control). Preadolescent weight and height from electronic health records classified the following BMI percentiles: normal weight, <
85th percentile (referent)
overweight (85th to <
95th percentile)
obesity (≥95th percentile)
moderate obesity (100 to <
120% of 95th percentile)
and severe obesity (≥120% of 95th percentile). Log-binomial regression models estimated adjusted relative risk (aRR) and 95% CI of BMI categories associated with fetal exposure to GDM severity and infant diet (inadequate BF, <
6 months or adequate BF, ≥6 months, combined with or without SSB/FJ intake). RESULTS: Among preadolescents, 17.6% had overweight, 18.2% had moderate obesity, and 7.6% had severe obesity. Compared with adequate BF with no SSB/FJ, aRR (95% CI) of developing obesity was 1.55 (95% CI: 1.05-2.30) for inadequate BF with SSB/FJ intake and 1.50 (95% CI: 1.01-2.21) for adequate BF with SSB/FJ intake, independent of GDM severity and covariates. The aRR (95% CI) of developing severe obesity was 3.80 (95% CI: 1.55-9.29) for inadequate BF with SSB/FJ intake versus adequate BF without SSB/FJ intake. CONCLUSIONS: BF adequacy and avoidance of sugary beverages in early life are modifiable lifestyle behaviors that may combat preadolescent obesity in infants exposed to GDM, suggesting potential longer-term benefits on child cardiometabolic health.