[Umbilical and maternal amino acid concentrations in appropriate and small for gestational age infants]

Serum amino acid concentrations were determined in 63 pregnant women and their infants at delivery. Samples were obtained from 47 appropriate for gestational age infants (AGA) and 16 small for gestational age infants (SGA). The SGA group had significantly lower concentrations of total amino acid, compared with those of AGA, in both the umbilical and maternal blood. The essential amino acids of the cord, such as isoleucine and threonine, and maternal essential amino acids like threonine and arginine in the SGA group were lower than those in the AGA group. In contrast, nonessential amino acid concentrations, such as alanine, proline and aspartic acid were significantly higher in the umbilical blood of the SGA infants, while there were no differences in the maternal blood of both AGA and SGA groups. There was a positive relationship between maternal and umbilical total amino acid concentrations in the AGA group, but no relationship exists in the SGA group.