Impact of gestational diabetes detection thresholds on infant growth and body composition: a prospective cohort study within a randomized trial

Objective: Gestational diabetes mellitus (GDM) is associated with offspring metabolic disease, including childhood obesity, but causal mediators remain to be established. We assessed the impact of lower versus higher thresholds for detection and treatment of GDM on infant risk factors for obesity, including body composition, growth, nutrition and appetite.

Research design and methods: Prospective cohort study within the GEMS Trial; pregnant women were randomly allocated to detection of GDM using the lower criteria of the International Association of Diabetes and Pregnancy Study Groups or higher New Zealand criteria (ACTRN12615000290594). Randomly selected Control infants of women without GDM were compared with infants exposed to: A) GDM by lower but not higher criteria, with usual treatment for diabetes in pregnancy; B) GDM by lower but not higher criteria, untreated; C) GDM by higher criteria, treated. The primary outcome was whole-body fat mass at 5-6 months.

Results: 760 infants enrolled; 432 assessed for the primary outcome. Fat mass was not significantly different between Controls (2.05kg) and exposure groups: A) GDM by lower but not higher criteria, treated (1.96kg), aMD -0.09 95%CI -0.29,0.10; B) GDM by lower but not higher criteria, untreated (1.94kg), aMD -0.15 95%CI -0.35,0.06; C) GDM detected and treated using higher thresholds (1.87kg), aMD -0.17 95%CI -0.37,0.03.

Conclusion: GDM detected using lower but not higher criteria, was not associated with increased infant fat mass at 5-6 months, regardless of maternal treatment. GDM detected and treated using higher thresholds was also not associated with increased fat mass at 5-6 months.