Understanding determinants of unequal distribution of stillbirth in Tehran, Iran: a concentration index decomposition approach

OBJECTIVE The present inquiry set to determine the economic inequality in history of stillbirth and understanding determinants of unequal distribution of stillbirth in Tehran, Iran. METHODS A population-based cross-sectional study was conducted on 5170 pregnancies in Tehran, Iran, since 2015. Principal component analysis (PCA) was applied to measure the asset-based economic status. Concentration index was used to measure socioeconomic inequality in stillbirth and then decomposed into its determinants. RESULTS The concentration index and its 95% CI for stillbirth was -0.121 (-0.235 to -0.002). Decomposition of the concentration index showed that mother's education (50%), mother's occupation (30%), economic status (26%) and father's age (12%) had the highest positive contributions to measured inequality in stillbirth history in Tehran. Mother's age (17%) had the highest negative contribution to inequality. CONCLUSIONS Stillbirth is unequally distributed among Iranian women and is mostly concentrated among low economic status people. Mother-related factors had the highest positive and negative contributions to inequality, highlighting specific interventions for mothers to redress inequality.