Objective — To estimate the risk for adverse perinatal outcomes for women who met the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria but not the two-step criteria for gestational diabetes mellitus (GDM).
Design — Population‐level cross‐sectional study.
Setting — Ontario, Canada.
Population — A total of 90 140 women who underwent a 75-g oral glucose tolerance test.
Methods — Women were divided into those who met the diagnostic thresholds for GDM by 2‐step criteria and were therefore treated, those who met only the IADPSG criteria for GDM and so were not treated, and those who did not have GDM by either criteria.
Main Outcome Measures — Hypertensive disorders of pregnancy, preterm delivery, primary caesarean section, large-for-gestational-age, shoulder dystocia and neonatal intensive care unit admission.
Results — Women who met the IADPSG criteria had an increased risk for all adverse perinatal outcomes compared to women who did not have GDM. Women with GDM by two‐step criteria also had an increased risk of most outcomes. However, their risk for large for gestational age neonates and for shoulder dystocia was actually lower than that of women who met IADPSG criteria.
Conclusion — Women who met IADPSG criteria but who were not diagnosed with GDM based on the current two‐step diagnostic strategy, and were therefore not treated, had an increased risk for adverse perinatal outcomes compared to women who do not have GDM. The current strategy for diagnosing GDM may be leaving women who are at risk for adverse events without the dietary and pharmacological treatments that could improve their pregnancy outcomes.