Abstract
BACKGROUND: Segregation is the degree to which two or more groups live separately. While US research has linked segregation to increased stillbirth risk, studies from Latin America have yet to explore this. This study investigated the association between the racial and income segregation index (SI) and stillbirth prevalence in Brazil. METHODS: We used nationwide birth data from Brazil in 2018 (live births from Live Birth Information System, SINASC, and stillbirths from Mortality Information System, SIM). Income and racial SI were calculated using the 2010 national census and analyzed as quintiles with the least segregated group as the reference. Odds ratios were calculated using a logistic regression model, adjusting for infant sex, maternal age, education, previous fetal loss, and the municipal level percentage of the population earning less than half the minimum wage. The sub-analysis was stratified by city size, area-level stillbirth prevalence, and stillbirth type (intrapartum or antepartum). RESULTS: Two million seven hundred seventy-one thousand two hundred seventy-two live-born and stillborn in 2018 were included in the analysis. Women in municipalities with high income and racial SI were older, had more education, and had more previous fetal loss. Women in municipalities with the highest income SI had a 25.1% higher risk of delivering a stillbirth (95% CI: 1.202-1.303). Those in the highest racial SI municipalities had a 5.5% lower risk of delivering a stillbirth compared to those in the quintile with the lowest racial SI (95% CI: 0.908-0.984). In regions with low stillbirth prevalence, a dose-response relationship was observed between income segregation and stillbirth, with the risk of stillbirth among those with the highest income SI being more than twice that of the least segregated (OR 2.086, 95% CI: 1.494-2.911). In larger cities, racial and income segregation were associated with reduced odds of stillbirth. The effect of income SI was larger for intrapartum stillbirths. CONCLUSIONS: We observed that income segregation increases the odds of stillbirth, especially in municipalities with low stillbirth prevalence, while the association for racial segregation was less consistent.