Neighbourhood Social Vulnerability and Preterm Birth Risk Among Infants With Trisomy 21: A Statewide Analysis

BACKGROUND: Residing in socioeconomically vulnerable areas is known to be associated with increased preterm birth (PTB) risk in the general population. However, the relationship between social vulnerability and PTB remains unexplored among infants with trisomy 21, who experience more than twice the PTB rate of the general population. OBJECTIVES: The primary objective was to examine the association between maternal socioeconomic vulnerability, as measured by the SVI, and PTB among infants with trisomy 21. METHODS: We conducted a retrospective cohort study among infants with trisomy 21 born in Texas (1999-2018). We examined the association between neighbourhood vulnerability, measured by Social Vulnerability Index (SVI) quartiles, and PTB utilising data from the Texas Birth Defects Registry. Using Poisson regression, we estimated crude and adjusted risk ratios (RRs) and 95% confidence intervals (CIs), accounting for maternal demographic characteristics and health factors. RESULTS: Of the 8823 eligible infants included in the analysis, 2269 (25.7%) were born preterm. Maternal residence in the highest vulnerability quartile was associated with an increased risk of PTB (RR 1.17, 95% CI 1.04, 1.32) and moderate to late PTB (RR 1.19, 95% CI 1.05, 1.35), compared to the least vulnerable quartile. In secondary analyses stratified by race/ethnicity, the association with high vulnerability was particularly strong among non-Hispanic Black women (RR 1.44, 95% CI 1.00, 2.07). CONCLUSIONS: These findings underscore the importance of neighbourhood social vulnerability in influencing perinatal health risks, particularly PTB among infants with trisomy 21.