CONTEXT: Children exposed to gestational diabetes mellitus (GDM) in utero are at high risk of developing overweight and obesity, but their postnatal growth trajectories and risk profiles remain unclear.

OBJECTIVE: We aimed to identify distinct body mass index (BMI) trajectories from birth to 10 years of age in children exposed to GDM and to explore their associations with infant and maternal characteristics.

METHODS: This nationwide cohort study linked data from Danish registries on 15 509 children exposed to GDM in utero, born in Denmark from January 2008 to October 2019. We applied latent class trajectory modeling to identify distinct BMI trajectories. Associations of BMI trajectories with infant and maternal characteristics were analyzed using multiple linear regression.

RESULTS: We identified 3 distinct BMI trajectories characterized by a "normal" (60%), a "late accelerating" (28%) and an "early accelerating" (12%) BMI trajectory, the 2 latter at risk of overweight and obesity, respectively, at age 10 years, relative to World Health Organization child growth standards. Children in the "late accelerating" BMI trajectory were more often born large for gestational age (P < .001). More children in the "early accelerating" BMI trajectory were boys, born small for gestational age, and had mothers with a higher pre-pregnancy BMI compared to the other groups (P < .001).

CONCLUSION: Children exposed to GDM in utero differ widely in their BMI trajectory. The detection of risk profiles based on early BMI growth and infant and maternal characteristics provides an opportunity for future targeted care and prevention.