(600) Does Mild Gestational Diabetes Increase Risk for Adverse Maternal Pregnancy Outcome?

Pregnancies complicated by gestational diabetes (GDM) are at a higher risk for adverse maternal pregnancy outcomes (APO). If mild GDM (MGDM), the diagnosis of having an abnormal screening but normal diagnostic oral glucose tolerance test (OGTT), is associated with increased risks of APO is less clear. Using the large multi-site prospective cohort Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-be (nuMoM2b), we investigated if MGDM associates with APO (composite including one or more of the following: hypertensive disorders of pregnancy, cesarean section, preterm premature rupture of membranes, or preterm birth).

Study Design:

This is a secondary analysis of nuMoM2b. MGDM included 1-hour (hr) screening OGTT >135 mg/dL & < 2 elevated values on the 3-hr diagnostic OGTT (Carpenter-Coustan cutoffs). MGDM was subclassified into 3 groups: no abnormal values on 3-hr (GDM1), only abnormal fasting value on 3-hr (GDM2), & only abnormal post-glucose load value on 3-hr (GDM3). No GDM (NGDM) included normal 1-hr screening test. Wilcoxon Rank-Sum & Chi-square tests compared continuous and categorical variables respectively. Multivariable logistic regression calculating adjusted odds ratio (AOR) controlling for maternal age, race & body mass index were performed.

Results: Of N=9289 subjects, 68.4% (n=6352) had NGDM, 7% (n=651) MGDM, 3% (n=280) GDM1, 0.4% (n=37) GDM2, & 3.6% (n=334) had GDM3 respectively (Table 1a). 39.8% of NGDM, 43.2% MGDM, 40.4% of GDM1, 54% of GDM2, & 44.3% GDM3 had an APO. When controlling for confounders, those with MGDM (AOR 1.4, 95% CI 1.1-1.9, p=0.02) & GDM1 (AOR 1.6, 95% CI 1.1-2.2, p< 0.02) had significantly higher odds of experiencing an APO.

Conclusion: It is unequivocal that GDM is associated with APOs. Innovatively, our data demonstrate that those with no elevated values on a 3-hr OGTT (theoretically the lowest risk group) had the highest odds of developing an APO. Further studies investigating the mechanistic underpinnings connecting the phenotypes of MGDM and APO development are imperative.