The Association of Community Social Vulnerability and Racial Disparities with Infant Preterm Birth and Low Birthweight

This study aimed to examine the association of community-level social vulnerability with infant preterm birth (PTB) and low birth weight (LBW). National Center for Health Statistics Restricted Vitals Statistics birth cohort linked files of infants born preterm (<37 weeks gestation) and with LBW (<2,500 g). The exposure was the CDC's Social Vulnerability Index (SVI) (five quintiles, ranked from lowest to highest social vulnerability). We performed multivariable logistic regression for each outcome with SVI as the exposure (referent Quintile 1). We assessed for effect modification of SVI by Black and White race with stratum-specific estimates for other racial groups. All models were adjusted for maternal characteristics and reported adjusted odds ratios (aOR) with 95% confidence intervals (CI). There were 3,791,712 infants analyzed: 379,777 (10%) with PTB and 314,568 (8.3%) with LBW. In the multivariable models the association between higher SVI counties and PTB was higher among Black (Quintile 4: aOR [95% CI] = 1.17 [1.07, 1.28]; Quintile 5: 1.21 [1.11, 1.32]) compared with White infants (Quintile 4: 1.06 [1.02, 1.10]; Quintile 5: 1.09 [1.01, 1.18]). There was effect modification for SVI by race for PTB, but not LBW. LBW was associated with higher SVI counties in a step-wise fashion (Quintile 3: 1.04 [1.01, 1.08]; Quintile 4: 1.08 [1.04, 1.12]; Quintile 5: 1.12 [1.07, 1.18]), with higher odds for infants of Asian (1.45 [1.39, 1.51]) and Black (1.92 [1.85, 2.00]) compared with White race, and Hispanic ethnicity (1.05 [1.01, 1.09]). PTB and LBW are associated with increased community-level social vulnerability and with racial disparities.