Association Between Neighborhood Deprivation in Early Pregnancy and Gestational Diabetes Mellitus.

OBJECTIVE:To evaluate whether having a pregnancy in a deprived neighborhood was associated with an increased risk of gestational diabetes mellitus (GDM) compared with having a pregnancy in the least-deprived neighborhoods. METHODS:This was a retrospective observational cohort study of pregnant individuals within Kaiser Permanente Northern California from 2011 to 2018 with residential history from prepregnancy through 24 weeks of gestation and clinical data from prepregnancy through delivery. The primary outcome was a diagnosis of GDM. Neighborhood deprivation was characterized with an index aggregating multiple indicators of Census tract-level sociodemographic information. Mediation analysis using inverse odds ratio weighting estimated the mediation effects of prepregnancy body mass index (BMI), gestational weight gain, smoking tobacco, and illegal drug use before GDM diagnosis. RESULTS:Overall, 214,375 pregnant individuals were included, and 11.3% had a diagnosis of GDM. Gestational diabetes prevalence increased with neighborhood deprivation from 10.0% in the lowest Neighborhood Deprivation Index quintile to 12.7% in the highest quintile. Compared with pregnant individuals in the least deprived neighborhoods (quintile 1), pregnant individuals in quintiles 2-5 had elevated risk of GDM (relative risk [95% CI]) when adjusted for maternal age, parity, insurance type, and residential history (quintile 2, 1.17 [1.10-1.23]; quintile 3, 1.38 [1.30-1.46]; quintile 4, 1.54 [1.45-1.63]; quintile 5, 1.71 [1.62-1.82]). There was a dose-response relationship between relative risk of GDM and increasing quintile of neighborhood deprivation (P for trend <.001). Prepregnancy BMI mediated 45.8% (95% CI, 40.9-50.7%) of the association. Other potential mediators were found to mediate a small if not negligible proportion of this association (2.4-3.6%). CONCLUSION:Neighborhood deprivation was associated with GDM, and a considerable proportion of this relationship was mediated by prepregnancy BMI.