Neonatal mortality still remains a complex challenge to be addressed. In Brazil, 60% of neonatal deaths occur among preterm infants with a gestational age of 32 weeks or less (≤32w). The aim of this study was to evaluate the factors involved in the high mortality rates among newborns with a gestational age ≤32w in a socioeconomically developed southern city in Brazil. Data on retrospective births and deaths (2000-2014) were analyzed from two official Brazilian national databases. The risk of neonatal death for all independent variables (mother's age and schooling, prenatal visits, birth hospital, delivery method, gestational age, and the newborn's sex, age, and birth year, gemelarity, congenital anomalies and birthplace) was assessed with a univariable and a multivariable model of Cox's semiparametric proportional hazards regression (p < 0.05). Data of 288,904 newborns were included, being 4,514 with a gestational age ≤32w. The proportion of these early newborns remained stable among all births, while the neonatal mortality rate for this group tended to decrease (p < 0.001). The adjusted risk was significantly for lower birthweight infants (mean 659.13 g) born from Caesarean (HR 0.58 [95% CI 0.47-0.71]), but it was significantly higher for heavier birth weight infants (mean 2,087.79) also born via Caesarean section (HR 3.71 [95% CI 1.5-9.15]). Newborns with lower weight seemed to benefit most from Cesarean deliveries. Effort towards reducing unacceptably high surgical deliveries must take into account cases that the operations may be lifesaving for mother and/or the baby. The reduction in infant mortality rates over the past few years has enabled Brazil to attain the fourth goal of the eight Millennium Development Goals proposed by the United Nations: to reduce infant mortality by two-thirds between 1990 and 2015 1. However, unlike postneonatal mortality, neonatal mortality has not yet reached acceptable rates considering the country's technological and economic development. Neonatal mortality in Brazil still remains a complex challenge to be addressed 2. Most neonatal deaths occur among preterm newborns 3. In Brazil, 60% of neonatal deaths occur among preterm infants with a gestational age of 32 weeks or less 4. Of all neonatal deaths, 75% occurred between zero and six days of age, and one in four deaths occurred during the first 24 hours of life 1,5,6. Despite this scenario, there are few studies that seek to elucidate the causes or factors contributing to mortality in this population. This study investigated the possible contributing factors involved in the high mortality rates among newborns with a gestational age of up to 32 weeks at a socioeconomically developed capital city in southern Brazil. Data were obtained through the vital statistics published by two official health information systems combined by means of a record linkage in a time series. Methods Porto Alegre is the capital city of the state of Rio Grande do Sul, Brazil, with a population of 1,467,823 (2013) and a very high Human Development Index...