Neighborhood Socioeconomic Disadvantage and Abnormal Birth Weight

OBJECTIVE: To examine whether exposure to community or neighborhood socioeconomic disadvantage as measured by the ADI (Area Deprivation Index) is associated with risk of abnormal birth weight among nulliparous individuals with singleton gestations. METHODS: This was a secondary analysis from the prospective cohort NuMoM2b study (Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be). Participant addresses at cohort enrollment between 6 and 13 weeks of gestation were geocoded at the Census tract level and linked to the 2015 ADI. The ADI, which incorporates the domains of income, education, employment, and housing quality into a composite national ranking of neighborhood socioeconomic disadvantage, was categorized by quartiles (quartile 1, least disadvantaged, reference; quartile 4, most disadvantaged). Outcomes were large for gestational age (LGA; birth weight at or above the 90th percentile) and small for gestational age (SGA; birth weight below the 10th percentile) compared with appropriate for gestational age (AGA; birth weight 10th-90th percentile) as determined with the 2017 U.S. natality reference data, standardized for fetal sex. Multinomial logistic regression models were adjusted for potential confounding variables. RESULTS: Of 8,983 assessed deliveries in the analytic population, 12.7% (n=1,143) were SGA, 8.2% (n=738) were LGA, and 79.1% (n=7,102) were AGA. Pregnant individuals living in the highest ADI quartile (quartile 4, 17.8%) had an increased odds of delivering an SGA neonate compared with those in the lowest referent quartile (quartile 1, 12.4%) (adjusted odds ratio [aOR] 1.32, 95% CI 1.09-1.55). Pregnant individuals living in higher ADI quartiles (quartile 2, 10.3%; quartile 3, 10.7%; quartile 4, 9.2%) had an increased odds of delivering an LGA neonate compared with those in the lowest referent quartile (quartile 1, 8.2%) (aOR: quartile 2, 1.40, 95% CI 1.19-1.61; quartile 3, 1.35, 95% CI 1.09-1.61; quartile 4, 1.47, 95% CI 1.20-1.74). CONCLUSION: Neonates of nulliparous pregnant individuals living in U.S. neighborhoods with higher area deprivation were more likely to have abnormal birth weights at both extremes.