Plasma somatomedin activity and nutrition in the newborn infant.

Plasma somatomedin activity was measured by postnatal pig cartilage bioassay in 11 full term normal for dates, 10 preterm normal for dates and 5 full term small for dates newborn infants on the 2nd, 5th and 10th day after birth. On day 2 mean somatomedin activity was lower than in the adult in all three groups of infants. After that, a slight but not significant rise in somatomedin activity occurred in the full term but not in the preterm infants. No significant correlation was found between somatomedin activity and calorie, protein, lipid or carbohydrate intake.