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.

Purpose Identify factors associated with infant mortality by a hierarchical model based on socioeconomic, health care, obstetric and biological determinants in a northeastern Brazilian capital. Methods Observational, retrospective cohort study based on secondary data of births and deaths of infants of mothers living in the city of Teresina. ResultsBased on the distal level of determination of infant mortality, the characteristics that remained statistically significant were maternal age, maternal education and maternal occupation (p < 0.001). In the intermediate level, all variables were statistically significant, particularly the type of pregnancy and delivery (p < 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 (p < 0.001). Conclusions This study evidenced that, in addition to biological factors, socioeconomic status and maternal and child health care are important to determine infant mortality. Palavras-chave► mortalidade infantil ► fatores de risco ► sistemas de informação ► planejamento em saúde ResumoObjetivo Identificar os fatores associados à mortalidade infantil por modelo hierárquico segundo determinantes socioeconômicos, assistenciais, obstétricos e biológicos em uma capital do Nordeste brasileiro. Métodos Estudo observacional, de coorte retrospectiva, com base em dados secundários de nascimentos e óbitos de crianças menores de um ano, de mães residentes no município de Teresina (PI).Resultados Para o nível distal de determinação da mortalidade infantil, as características que se mantiveram estatisticamente significativas foram idade materna, escolaridade materna e ocupação materna, com p < 0,001. No intermediário, todas as variáveis apresentaram significância estatística, com destaque para o tipo de gravidez e de parto, com p < 0,001. O sexo do bebê representou a característica do nível proximal que não obteve associação significativa com o desfecho, enquanto as demais variáveis desse nível estavam associadas, com p < 0,001. Conclusões Além da determinação da mortalidade infantil pelos fatores biológicos, destacou-se a importância da condição socioeconômica e da assistência à saúde materno-infantil.