Impact of maternal age and maternal somatic characteristics on newborn size.

Pregnancies during early adolescence were commonly thought to represent special risks, such as preterm delivery or low-weight newborns, resulting in increased mortality and morbidity of mother and child. An important biopsychosocial interaction can be assumed. In the present study the impact of maternal age and maternal somatic characteristics such as prepregnancy weight, stature, or pregnancy weight gain on newborn somatometric features (birth weight, birth length, head circumference, and arcomial circumference) using a dataset of 8,011 single term births were analyzed. The offspring of 215 extremely young mothers ages 12-16 years were significantly (P < 0.0001) lighter and smaller in all body dimensions than the offspring of older adolescent mothers, ages 17-19 years, and the offspring of adult gravida, ages 20-29 years, although no increased incidence of low-weight newborns (<2,500 g) could be observed. As expected, the youngest mothers were also significantly smaller and lighter than their older, biologically more mature counterparts, although the relative weight gain during pregnancy was highest in the youngest age group (23.4% vs. 22.9 and 22.1%, respectively). In general, age but also pregnancy weight gain and prepregnancy weight status were significantly associated with pregnancy outcome. Within term births taking place under sufficient psychosocial support, maternal somatic features had an important impact on newborn size. Copyright 2003 Wiley-Liss, Inc.