<span name="style_bold">Aim: </span>To identify the risk factors for preterm delivery in pregnant adolescents during their prenatal care. <span name="style_bold">Methods: </span>An observational cross-sectional study was conducted through secondary analysis of the data base from the original study <span name="style_italic">“Characteristics of prenatal care of pregnant adolescents, Obstetrics Department of the Rafael Angel Calderon Guardia Hospital, 2010”</span>. The variables related to prenatal care were categorized according to the yes/no dichotomy and by using a regression, the adjusted odds ratio (OR) regarding presence of preterm labor, was calculated for each of them. <span name="style_bold">Results: </span>The mean age of the patients was 16.6years (SD±1.6). Preterm delivery occurred in 13.3% of the cases (n= 48, 95% CI 10.1 to 17.4). The <span name="style_italic">medical illnesses associated to pregnancy </span>(OR3.5, 95% CI 1.3 to 9.6), <span name="style_italic">two or more pregnancies </span>(OR3.6, 95% CI 1.3 to 10.3) and <span name="style_italic">the lack of adequate prenatal care</span>(OR 10.1, 95% CI 3.2 to 32.3) were the main independent variables for preterm labor. <span name="style_bold">Conclusions: </span>Medical illnesses associated to pregnancy, two or more pregnancies and the lack of adequate prenatal care are the main independent variables in preterm labor in the adolescent population.Medical illnesses associated to pregnancy, two or more pregnancies and the lack of adequate prenatal care are the main independent variables in preterm labor in the adolescent population.

Pregnancy; adolescent; prenatal care; preterm delivery