Maternal growth during pregnancy and decreased infant birth weight.

We used stature and measurement of knee height to measure continued maternal growth during adolescent pregnancy in a sample of young gravidas (primigravidas and multiparas) and mature pregnant control subjects. Growth during pregnancy has been masked by a tendency of all gravidas to shrink while pregnant (approximately 0.5 cm over 6 mo of observation). Consequently, growth of many adolescent gravidas has not been clinically apparent. There was no effect on maternal growth during a first pregnancy in adolescence but this may be a result of the relatively good prepregnant nutrition status of the young gravidas in developed countries. Maternal growth during pregnancy, however, is associated with significantly decreased (-282 g, p less than 0.05) birth weight for infants when maternal growth continues during a subsequent adolescent pregnancy. This observation is consistent with the hypothesized competition between the metabolic demands of the growing adolescent mother and the nutrient needs of her developing fetus.