This study aimed to evaluate the quality of socioeconomic and demographic data in the Brazilian Mortality Information System (SIM), in relation to infant mortality. The article assesses the system's potential for monitoring inequalities in infant mortality in various States in the country. Accessibility, timeliness, methodological clarity, incompleteness, and consistency were explored as quality indicators. Selected variables were: race, birth weight, gestational age, medical care, parity, and maternal schooling, age, and occupation. The study also reviewed the system's working documentation and the scientific literature on infant mortality. Proportions of data incompleteness were calculated by region and State, identifying factors that might influence (in)completeness using logistic regression. Despite the database's accessibility and the relevance of most of its variables, the system has serious quality problems: confusing instructions in the information manual concerning missing data, misclassification of maternal occupation, lack of data on the informant's race/ethnicity, and high proportions of incomplete information. The system does not appear to be a reliable source for monitoring, evaluating, and planning measures to minimize infant health inequalities.
Infant Mortality; Mortality Registries; Health Inequity; Quality
