Influence of Neighborhood Socioeconomic Status on Adverse Outcomes in Pregnancy.

PURPOSE: To evaluate whether ZIP-code level neighborhood socioeconomic status (SES) is associated with adverse pregnancy outcomes. METHODS: A retrospective study of 2009-2014 Oregon Health and Science University (OHSU) births with maternal ZIP codes in one of 89 Portland metropolitan area ZIP codes. Deliveries with ZIP codes outside of the Portland metro area were excluded. Deliveries were stratified by SES based on ZIP code median household income: low (below 10th percentile), medium (11th-89th percentile), and high (above 90th percentile). Univariate analysis and multivariable logistic regression with medium SES as the reference group evaluated perinatal outcomes and strength of association between SES and adverse events. RESULTS: This study included 8118 deliveries with 1654 (20%) classified as low SES, 5856 (72%) medium SES, and 608 (8%) high SES. The low SES group was more likely to be younger, have a higher maternal BMI, have increased tobacco use, identify as Hispanic or Black, and less likely to have private insurance. Low SES was associated with a significantly increased risk of preeclampsia (RR 1.23 95% CI 1.01-1.49), but this was no longer significant after adjusting for confounders (aRR 1.23 95% CI .971-1.55). High SES was negatively associated with gestational diabetes mellitus (GDM), even after adjusting for confounders (aRR 0.710, 95% CI 0.507-0.995). CONCLUSION: In the Portland metropolitan area, high SES was associated with a lower risk of GDM. Low SES was associated with a higher risk of preeclampsia before accounting for covariates. ZIP code-based risk assessment may be a useful indicator in detecting healthcare disparities.