The objective of this study was to compare pregnancy evolution, newborn's weight, its somatometry and Apgar's qualification of teenagers and the general population in a community where the socio-economic factor is similar among those two groups. Three hundred and two pregnancies in teenagers were analyzed, 69 of 12-15 years and 233 of 16-17 years at the time of pregnancy, against a control group of 304 pregnant patients of 18-39 years. It was a prospective, comparative, longitudinal study. Average age at the first delivery of the 606 patients was 18.1 years. There were no significant difference among the groups as to occupation. There was not significant difference among the three groups as to pre-natal control, weeks of gestation incidence of threatening abortion, toxemia, bleeding of the second half of pregnancy, premature rupture of membranes, proportion of deliveries and cesarean sections, as well as forceps application and newborns' sex. The most common indications of cesarean section in teenagers were CPD and acute fetal suffering, in the control group were CPD and pelvic presentation. There was significant difference comparing the weight, Apgar qualification at one minute and at three minutes in the 16-17 years group, and older of 18 years being greatest in the last group. There was significant difference in size, cephalic perimeter, thoracic perimeter and PC/pa ratio among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)