Relationship of maternal protein turnover and lean body mass during pregnancy and birth length

Epidemiological evidence shows that small size at birth is associated with an increased risk of developing cardiovascular and metabolic disease in adu lt life. We have examined the relationships between size at birth and mater nal body composition and protein turnover in normal pregnant women. A group of 27 multiparous Caucasian women with singleton pregnancies were studied at around 18 and 28 weeks' gestation. Body composition was determined by an thropometry, and whole-body protein turnover was estimated by using a singl e oral dose of [N-15] glycine and the end-product method. The baby's weight and length were measured within 48 h of birth. Mothers with a greater lean body mass had higher rates of protein turnover at 18 weeks' gestation. Thi s association was largely accounted for by differences in the mother's visc eral, rather than muscle, mass. Mothers who had higher protein turnover at 18 weeks' gestation had babies that were longer at birth. After adjustment for the duration of gestation and the baby's sex, 26% of the variation in l ength at birth was accounted for by maternal protein synthesis at 18 weeks' gestation. Maternal protein intake was not associated with the baby's birt h length. Thus the mother's ability to nourish her fetus is influenced by h er body composition and her rate of protein turnover. Dietary intake does n ot adequately characterize this ability.