Developing a social vulnerability index for antenatal care screening of risk for adverse maternal and perinatal outcomes

OBJECTIVE: Social determinants of health influence maternal and perinatal outcomes, yet tools to operationalize these risks in clinical care remain scarce. We aimed to study social determinants in Brazilian pregnant women and develop a social vulnerability index (SVI) that could correlate with pregnancy and perinatal outcomes. METHODS: The present study was a secondary analysis of 1565 low-risk nulliparous women enrolled in two Brazilian cohort studies. We selected vulnerability indicators from sociodemographic data and tested the performance and risk association of multiple SVI models with any adverse outcome (preterm birth, gestational diabetes mellitus, pre-eclampsia, small or large for gestational age, low 5-min Apgar score, neonatal intubation, neonatal intensive care unit admission, fetal or neonatal death) using chi-square tests, logistic regression, and receiver operating characteristic analysis. RESULTS: Advanced maternal age, non-white ethnicity, and exclusive publicly funded antenatal care were the most consistent vulnerability predictors of adverse outcomes. The final three-variable SVI demonstrated a significant dose-response gradient, with maternal adverse outcomes increasing from 16.4% (no vulnerabilities) to 43.8% (3 vulnerabilities) and perinatal adverse outcomes rising from 22.1% to 35.6%. The model presented a sensitivity of 64.71%, a specificity of 42.56%, a positive predictive value of 47.46% and a negative predictive value of 60.07% for any adverse outcome. CONCLUSION: The three-variable SVI offers a simple, reproducible, and context-adapted screening tool for primary care. Either for individual or population screening, it can be easily combined with clinical risk assessment, targeting those who may benefit from equity-oriented maternal health strategies.