Avoidable deaths have been employed as indicators of health care quality. The aim of this study was to identify factors associated with avoidable deaths from birth to four years of age among children from the 2004 Pelotas (Brazil) birth cohort study. From January 1st, 2004, to December 31st, 2005, deaths were monitored on a daily basis and the causes were investigated and classified according to avoidability. After the first year, deaths were monitored through the Mortality Information System. A total of 94 children died during this period. It was possible to classify 92 deaths, 70 of which were preventable. Low family income, fewer prenatal visits and poor-quality prenatal care, preterm birth, low 5-minute Apgar score, and no breastfeeding in the first 24 hours of life were associated with increased risk of death. Prematurity was present in 39 deaths, but only five of these would have been prevented by measures provided during prenatal care. Although limited, compliance with antenatal care program guidelines is still the most important strategy for preventing avoidable deaths in childhood, particularly among the poorest children.