LATEBREAKER
Health Disparities
Census-Tract Level Social Vulnerability and Preterm Birth in California Jocelyn Burridge* Jocelyn Burridge Rebecca Baer Christina Chambers
Background: Preterm birth (PTB) is a leading cause of neonatal morbidity and mortality. Existing literature has shown that community factors influence risk of PTB. This has led to increasing use of the Social Vulnerability Index (SVI) as a proxy for individual risk factors.
Objectives: This study investigated the association between SVI and PTB and explored the moderating effect of SVI on risk of pregnancy-induced hypertension in relation to PTB.
Methods: This retrospective study utilized linked hospital discharge and vital statistics data from all pregnancies in California 2018-2021 from the UC San Diego Study of Outcomes in Mothers and Infants (SOMI). The study sample consisted of 1,022,097 singleton livebirths linked to the CDC’s 2020 SVI metrics by census tract. SVI was categorized in quintiles (Very Low, Low, Moderate, High, Very High), determined by socioeconomic status, household composition, racial/ethnic status, and housing/transportation metrics. Pregnancy-induced hypertension was identified by ICD code. PTB (<37 weeks) was obtained from vital statistics. Logistic regression models were adjusted for maternal age, insurance status, education, body mass index, nulliparity, pre-existing hypertension, smoking, and rural-urban classification. An interaction term for pregnancy-induced hypertension and SVI was tested in the model.
Results: Significant associations were found between PTB and successively higher SVI quintiles compared to Very Low SVI quintile, adjusting for confounders (see table). Highest risk was in the Very High SVI quintile (adjusted odds ratio [aOR] 1.34, 95% Confidence Interval [CI] 1.30, 1.39). Increased risks were also seen for very preterm birth (<32 weeks) (Very High vs Very Low SVI: aOR 1.81, 95% CI [1.66, 1.97]). A significant interaction between hypertension and SVI was found, suggesting SVI amplifies the impact of hypertension on risk of PTB.
Conclusion: There was a significant correlation between higher SVI and PTB at the census tract level. This highlights the potential for SVI as a predictive tool for assessing risk of PTB and underlines the need for targeted interventions in high SVI regions.
