Developmental and nutritional determinants of pregnancy outcome among teenagers.

To investigate the determinants of low birth weight in infants born to adolescent mothers, we studied the obstetric population attended at the Maternity Hospital of Lima, Peru. From this population, 1256 gravidas, ranging in age from 12 to 25 years, volunteered to participate in this study. Anthropometric and biochemical measurements were used to evaluate the nutritional status and physiological maturity of the mother and newborn. For analytical reasons the young teenaged mothers (less than 15 years) were classified as either still-growing or having completed their growth, depending on their height relative to their parents' height. Similarly, the young teenagers were classified as either gynecologically immature or gynecologically mature depending on whether their gynecological age was less than or greater than 2 years. Our results indicate that young still-growing teenagers, even when matched for nutritional status, have smaller newborns than adult mothers. The data also demonstrate that maternal gynecological age per se does not affect prenatal growth. As inferred from multivariate analyses, it appears that the reduction in birth weight among young teenagers can be explained in part by a decreased net availability of nutrients resulting from the competition for nutrients between the mother's growth needs and the growth needs of her fetus and by an inability of the teenage placenta to maintain placental function adequately for active fetal growth.