Frequency and Risk Factors Associated with Prematurity: A Cohort Study in a Neonatal Intensive Care Unit.

: Prematurity rates remain high and represent a challenge for the public health systems of any country, with a high impact on neonatal mortality. This study aimed to evaluate the frequency and environmental and maternal-fetal risk factors for premature birth in a cohort of parturient women, with their newborns monitored in a neonatal intensive care unit at a private reference hospital. : A cohort was carried out between 2013 and 2018 among parturient women living in a capital city in the Northeast of Brazil whose newborns were admitted to the neonatal intensive care unit. This study was approved by the Research Ethics Committee of the University of Fortaleza. The information collected comprised data from both medical records and hydrosanitary data from maternal homes. : The prevalence of prematurity among live births ( = 9778) between 2013 and 2018 at this hospital was 23%. The frequency of prematurity among those eligible ( = 480) was 76.9%, and the frequency of eligible premature babies ( = 369) in relation to the total number of births in this period was 3.8%. In the multivariate analysis, the significant risk factors for prematurity were primigravida (RR = 1.104, 95%CI: 1.004-1.213) and hypertensive syndromes during pregnancy (RR = 1.262, 95%CI: 1.161-1.371), and the significant protective factor was the highest number of prenatal consultations (RR = 0.924, 95%CI: 0.901-0.947). : This study contributes to providing greater visibility to prenatal care and the understanding of complications during pregnancy and childbirth care. These results indicate the need to implement public policies that promote improvements in the population's living conditions and care for pregnant women to reduce premature births and, consequently, neonatal and infant mortality.