In a prospective study, a population of 528 pregnant primiparas aged 13-17 years were surveyed who gave birth at the obstetrical clinic of the Medical University of Pleven, Bulgaria, during the period of 1988-90. The data were compared to data of a sample of 100 pregnant primiparas aged 20-24 years and the data of the literature. The rate of abortion among these adolescents was 2.4% compared to 1.78%, 7.44%, and 9.37%, respectively, reported from authors in Spain (1980), Tunisia (1991), and the US (1983). These 528 births to adolescents accounted for 5.48% of a total of 9635 births. This percentage exceeded the rate of 1.2% among 112 women reported by a French researcher (1984). Pregnant girls under 15 years of age face more medical complications. In this sample there were 72 (13.64%) cases of anemia, 52 (9.85%) cases of premature rupture of the amniotic sac, 13 (2.46%) cases of preeclampsia (3-18% reported in the literature), and 4 (0.76%) cases of eclampsia. In most cases delivery occurred spontaneously, and it lasted 8 hours and 35 minutes in the adolescents compared to 10 hours and 37 minutes in the controls. Among the girls under age 15, often analgesics, tranquilizers, and anesthesia had to be used because of the instrumental extraction of the fetus. The high rate of cesarean section (5.11%) indicated pelvic-fetal disproportion, which was even higher (15%) as reported by other researchers. The rate of vaginal instrumental delivery amounted to 6.72%. Fetal retardation occurred in 1.32% vs. 9.33% reported in Tunisia and 6.69% in France. The adoption rate made up a 8.29% vs. 20.11% reported in Tunisia and 18.20% reported in France. 56.82% of these girls were of Gypsy origin; 51.70% were single or cohabiting with the father of the child; 14.20% were illiterate. The rate of stillbirths amounted to 0.76% (4 children) vs. 11.11% (Tunisia) and 3.25% (France). However, prematurity reached 17.99% in the adolescent groups compared to 4.7% in the controls (p 0.05).