Introduction: Prematurity is a serious public health problem due to morbidity, mortality and associated costs. Objective: To evaluate the relationship between sociodemographic, obstetric and psychosocial characteristics with the outcome of premature birth versus term births at the Guillermo Grant Benavente Hospital in Concepción, Chile, between the second semester of 2016 and the first semester of 2017. Method: Quantitative, observational case-control study. The sample consisted of 85 women with premature delivery and 85 with term delivery. A self-elaborated questionnaire and Abbreviated Psychosocial Assessment scale (EPsA) were used. The study was approved by the scientific ethics committee. Bivariate and multivariate analysis was performed, with a level of significance α = 0.05. The data were analyzed with the statistical software SPSS v.25.0. Results: There were no differences between the sociodemographic antecedents (age, socioeconomic level, marital status and education) between both groups. Only women with preterm birth had a higher percentage of paid work than full-term pregnant women (43.4% vs. 25.9%). Nutritional status and a history of previous preterm birth were not associated with a new delivery before 37 weeks. Interruption by cesarean section was significantly more frequent in preterm pregnancies than in the control group (p = 0.0377). Conclusions: In the studied population, the sociodemographic characteristics of the pregnant women were not related to the premature outcome of pregnancy. Biomedical factors are significantly related to this risk. It is necessary to evaluate the relevance of applying psychosocial scales in this population and to focus efforts to promote preconception control in women with a history of preterm birth and/or comorbidities.