Factors Associated with Infant Mortality in a Northeastern Brazilian Capital.

 Identify factors associated with infant mortality by a hierarchical model based on socioeconomic, health care, obstetric and biological determinants in a northeastern Brazilian capital.  Observational, retrospective cohort study based on secondary data of births and deaths of infants of mothers living in the city of Teresina.  Based on the distal level of determination of infant mortality, the characteristics that remained statistically significant were maternal age, maternal education and maternal occupation ( < 0.001). In the intermediate level, all variables were statistically significant, particularly the type of pregnancy and delivery ( < 0.001). The gender of the baby was the proximal level feature that had no significant association with the outcome, while the other variables of this level had association ( < 0.001).  This study evidenced that, in addition to biological factors, socioeconomic status and maternal and child health care are important to determine infant mortality.