This study characterizes the women receiving precarious prenatal care according to socio-demographic variables, mother's reproductive history, family support, satisfaction with pregnancy, and risk behavior during pregnancy. A total of 1,967 adolescents were interviewed in the immediate post-partum in public and outsourced maternity hospitals in the City of Rio de Janeiro. The dependent variable was the number of prenatal appointments (0-3; 4-6; 7 or more). The statistical analysis aimed to test the hypothesis of homogeneity of proportions, including bi- and multivariate analysis, using multinomial logistic regression, in which the reference category for the response variable was 7 or more prenatal visits. Higher (and statistically significant) proportions of insufficient number of prenatal visits (0-3) were associated with: precarious sanitation conditions; not living with the child's father; attempted abortion; and smoking, drinking, and/or drug use during pregnancy. The results strongly indicate that mothers with worse living conditions and risk behavior during pregnancy were the same who lacked access to prenatal care.