[Comparison between two cohorts of adolescent mothers in municipality of the Southeastern, Brazil]. / Comparação entre duas coortes de mães adolescentes em município do Sudeste do Brasil.

OBJECTIVE: To compare the prevalence of pregnancy among adolescents and analyze trends in some social and biological variables among two cohorts of adolescent mothers in Ribeirão Preto, Brazil, during 1978/79 and 1994. METHODS: Two cohorts of adolescent mothers were interviewed shortly after delivery, comprising 943 women in the first survey (1978/79) and 499 in the second (1994). Both surveys covered more than 98% of births in all childbirth clinics. Only singleton livebirths from adolescent mothers living in the municipality were included in the analysis. The Chi-square test was used for statistical analysis, with a 0.05 significance level. RESULTS: The percentage of adolescent mothers increased from 14.1% in 1978/79 to 17.5% in 1994 (p<0.05), mainly due to an increase in deliveries in the 13-17 years age group. There was a reduction in the number of smokers and mothers with lower schooling. The number of prenatal care visits increased. There was also an increase in the proportion of single mothers, of those who were employed and got private delivery care. Low birth weight and preterm birth rates remained unchanged for all of them. Cesarean section and forceps delivery rates increased substantially. Mothers in the 13-17 years age group however showed twice as much premature and low birth weight children, a higher proportion of single mothers with lower schooling, and higher rate of forceps delivery. CONCLUSIONS: Some characteristics of the adolescent mothers in the 13-17 years age group were more unfavorable when compared to the 18-19 years age group. The characteristics of adolescent age groups need to be better understood and taken into account in the prenatal and delivery care planning.