Diagnostic thresholds for pregnancy hyperglycemia, maternal weight status and the risk of childhood obesity in a diverse Northern California cohort using health care delivery system data

OBJECTIVE: To estimate the risk of childhood obesity associated with the various criteria proposed for diagnosis of gestational diabetes (GDM), and the joint effects with maternal BMI. METHODS: Cohort study of 46,396 women delivering at the Kaiser Permanente Northern California health care delivery system in 1995–2004 and their offspring, followed through 5–7 years of age. Pregnancy hyperglycemia was categorized according to the screening and oral glucose tolerance test values proposed for the diagnosis of GDM by the International Association of the Diabetes and Pregnancy Study Group (IADPSG), Carpenter Coustan (CC), and the National Diabetes Data Group (NDDG). Childhood obesity was defined by the International Obesity Task Force’s age and sex-specific BMI cut-offs. Poisson regression models estimated the risks of childhood obesity associated with each category of pregnancy glycemia compared to normal screening, and the joint effects of maternal BMI category and GDM by the CC and the IADPSG criteria. RESULTS: Compared with normal screening, increased risks of childhood obesity were observed for abnormal screening [RR (95% CI): 1.30 (1.22, 1.38)], 1+ abnormal values by the IADPSG or CC [1.47 (1.36, 1.59) and 1.48 (1.37, 1.59), respectively], and 2+ values by CC or NDDG [1.52 (1.39, 1.67) and 1.60 (1.43, 1.78), respectively]. Compared to obese women without GDM, obese women with GDM defined by the CC criteria had significantly increased risk of childhood obesity [1.20 (1.07, 1.34)], which was also observed for GDM by the IADSPG [1.18 (1.07, 1.30)], though GDM did not significantly increase the risk of childhood obesity among normal weight or overweight women. CONCLUSIONS: The risk of childhood obesity starts to increase at levels of pregnancy glycemia below those used to diagnose GDM and the effect of GDM on childhood obesity risk appears more pronounced in women with obesity. Interventions to reduce obesity and pregnancy hyperglycemia are warranted.