ObjectiveTo investigate the characteristics of women who had preterm birth (PTB) and related outcomes according to ethnicity.MethodsA secondary analysis of a multicenter cross-sectional study conducted in Brazil. Women who had PTB were classified by self-report as white and non-white. Clinical, pregnancy, and maternal data were collected through postpartum interviews and reviews of medical charts. The sociodemographic, obstetric and clinical characteristics of the women, as well as the mode of delivery and the neonatal outcomes among different ethnic groups were compared through a bivariate analysis.ResultsOf the 4,150 women who had PTB, 2,317 (55.8%) were non-white, who were more likely: to be younger than 19 years of age (prevalence ratio [PR]: 1.05; 95% confidence interval [95%CI]: 1.01–1.09); to be without a partner; to live on low income; to have lower levels of schooling; to have ≥ 2 children; to perform strenuous work; to be from the Northeastern region of Brazil rather than the from Southern region; to have a history of ≥ 3 deliveries; to have an interpregnancy interval < 12 months; to have pregnancy complications such as abortion, PTB, preterm premature rupture of membranes (pPROM), and low birth weight; to initiate antenatal care (ANC) visits in the second or third trimesters; to have have an inadequate number of ANC visits; to be under continuous overexertion; to smoke in the first and second or third trimesters; and to have anemia and gestational hypertension. The maternal and neonatal outcomes did not differ between the groups, except for the higher rate of low birth weight (73.7% versus 69.0%) in infants born to non-white women, and the higher rate of seizures (4.05% versus 6.29%) in infants born to white women.ConclusionUnfavorable conditions were more common in non-whites than in whites. Proper policies are required to decrease inequalities, especially in the context of prematurity, when women and their neonates have specific needs.