Potential Impact of Revising the Diagnostic Criteria for Gestational Diabetes on Maternal Pregnancy and Infant Perinatal Outcomes

AIMS: The revised diagnostic criteria for gestational diabetes (GDM) in New Zealand include lowering the fasting glucose from the current ≥ 5.5 to ≥ 5.3 mmol/L and replacing the current 2-h post-load glucose (≥ 9.0 mmol/L) with a 1-h glucose (≥ 10.6 mmol/L). We assessed the effects of these changes on the demographics of those diagnosed and their perinatal outcomes. MATERIALS AND METHODS: Participants in the GEMS trial were grouped as meeting only the revised criteria (Additional group), only the current criteria (Missed group), both criteria (Both-Criteria group), and neither criteria (Non-GDM group). RESULTS: GDM prevalence among 3921 participants was 6.8% using the revised criteria and 5.8% using the current criteria (risk ratio 1.18, 95% CI 1.00-1.40). Women in the Additional (n = 125) and Missed groups (n = 83), who would be affected by the changes, were more likely to be overweight/obese, have a family history of diabetes, and have Asian ethnicity than women in the Non-GDM group (n = 3562). They also had less gestational weight gain and more induced labors, while their infants were born earlier, had lower birthweight, and more neonatal hypoglycemia (all p < 0.001). Women in the Missed group had lower BMI and fewer were of Pacific ethnicity than the Both-Criteria group (n = 151). They also had less pharmacotherapy use and postpartum hemorrhage. CONCLUSIONS: Using the revised criteria will increase GDM diagnoses by identifying a high-risk group of women likely to benefit from treatment, but 35.5% of women currently treated for GDM will no longer be diagnosed, potentially compromising their health.