In Chile, 14 to 16% of births occur in teenage mothers. These mothers apparently have a higher frequency of premature labor, low birth weight and congenital malformations. Aim: To assess the frequency of prematurity, congenital malformations and weight at birth among the offspring of adolescent mothers. Patients and methods: The births occurred in a hospital between 1982 and 2001, were analyzed using the Latin American Collaborative Study for Congenital Malformations (ECLAMC) data base. Mothers were classified as teenagers when their age ranged between 10 and 19 years old and older when their age was over 20 years old. All women were subdivided as cases and controls. Results: The sample was formed by 894 teenage and 806 older mothers. Seven percent of both teenage and older mothers had offspring with one or more malformations. The incidence of low birth weight newborns and of prematurity was also similar in both groups of mothers. Conclusions: In this sample, offspring of teenage mothers do not have a higher frequency of malformations, low birth weight or prematurity (Rev Méd Chile 2003; 131: 1165-72).