Relationship of maternal amino acid profiles at 25 weeks of gestation to fetal growth.

In a study of the relationship of maternal nutrition to fetal development, the free amino acid concentration was determined in the plasma of 43 subjects sampled between the 20th to 30th (25 +/- 3.7) week of pregnancy. Significant positive correlations were found between mothers' 25-week plasma levels of aspartic acid, serine, alanine, tyrosine, ornithine, and arginine, and babies' size at birth. The concentration of total free amino acids in plasma from mothers of fetally malnourished infants, was significantly lower than that from mothers having normal babies. The branched chain amino acids isoleucine and valine were at normal levels, suggesting a sparing effect for these amino acids.