Prevalence of maternal hyperglycemic subtypes by race/ethnicity and associations between these subtypes with adverse pregnancy outcomes: Findings from a large retrospective multi-ethnic cohort in the United States

Aims With the two-step gestational diabetes mellitus (GDM) screening approach, hyperglycemic subtypes can be identified. We aimed to investigate racial/ethnic differences in the prevalence of hyperglycemic subtypes and to examine the associations between these subtypes and adverse pregnancy outcomes. Methods In this retrospective cohort, 11,405 pregnancies were screened using the two-step approach. Hyperglycemic subtypes included: pregnancy-impaired glucose intolerance-I (PIGT-I), PIGT-II, GDM-I (abnormal post-load glucose only), and GDM-II (abnormal fasting & post-load glucose). Modified Poisson regressions with robust error variance were used to estimate age-adjusted prevalence ratios (PR) of hyperglycemic subtypes and multivariable-adjusted risk ratios (RR) of adverse pregnancy outcomes. Results The prevalence of hyperglycemic subtypes was higher in Asians (PIGT-I: 1.51 [95% confidence interval 1.35–1.69]; PIGT-II: 2.18 [1.78–2.68]; GDM-I: 2.55 [2.10–3.10]; GDM-II: 1.55 [1.08–2.21]) and Hispanics (PIGT-I: 1.32 [1.16–1.50]; PIGT-II: 2.07 [1.67–2.57]; GDM-I: 1.69 [1.35–2.13]; GDM-II: 2.68 [1.93–3.71]) than non-Hispanic Whites (NHW). Despite low GDM prevalence, Japanese and Koreans had higher PIGT prevalence than NHW. PIGT-II was positively associated with hypertensive disorders of pregnancy (1.19 [1.02–1.38]), large-for-gestational age (1.73 [1.37–2.18]), and preterm birth (PB, 1.33 [1.05–1.68]). PIGT-I (1.23 [1.04–1.45]) and GDM-I (1.56 [0.87–1.71]) were positively related to PB. Conclusions The prevalence of hyperglycemic subtypes varies by race/ethnicity and they have distinct health implications.