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. 2009 Nov 25;91(2):357–365. doi: 10.3945/ajcn.2009.28457

TABLE 2.

Plasma amino acid concentrations (in μmol/L) during fasting in pregnant and nonpregnant women1

Nonpregnant First trimester Second trimester Third trimester P2
Aspartate 10.13 ± 2.94 7.2 ± 1.1 6.10 ± 0.7434 8.20 ± 2.1545 0.004
Glutamate 41.69 ± 9.04 34.45 ± 7.1 35.00 ± 12.22 41.50 ± 9.96 NS
Asparagine 45.25 ± 10.61 33.15 ± 3.243 37.10 ± 7.30 37.65 ± 6.86 0.051
Serine 133.44 ± 37.36 77.75 ± 14.73 79.10 ± 20.733 70.05 ± 18.673 <0.001
Glutamine 611.75 ± 99.50 403.5 ± 50.83 452.60 ± 43.683 443.90 ± 81.013 <0.001
Glycine 134.69 ± 96.88 72.15 ± 20.93 82.90 ± 20.39 77.00 ± 16.25 0.026
Histidine 214.94 ± 110.17 105.9 ± 47.9 120.30 ± 51.42 121.60 ± 40.54 NS
Threonine 152.19 ± 58.17 113.75 ± 24.8 174.70 ± 60.243 163.80 ± 45.554 0.032
Citrulline 27.38 ± 11.05 14 ± 3.453 14.60 ± 3.363 16.65 ± 4.043 0.001
Alanine 255.31 ± 65.77 186.4 ± 64.7 234.50 ± 66.86 219.50 ± 104.75 NS
Arginine 98.88 ± 43.18 44.85 ± 11.2 44.50 ± 9.43 48.70 ± 13.48 NS
Taurine 27.38 ± 20.59 15.95 ± 3.643 13.60 ± 3.073 10.95 ± 3.3334 <0.001
Tyrosine 54.56 ± 16.88 33.25 ± 5.43 33.60 ± 4.993 33.80 ± 5.423 0.003
Aminobutyric acid 22.88 ± 7.26 16.9 ± 3.033 15.50 ± 3.323 13.05 ± 3.4034 0.001
Methionine 31.00 ± 1.95 24.25 ± 4.053 25.20 ± 3.373 23.10 ± 3.923 0.001
Valine 199.50 ± 29.02 173.95 ± 28.63 158.70 ± 34.75 138.95 ± 20.7034 0.001
Tryptophan 38.19 ± 4.91 36.7 ± 3.80 32.50 ± 6.32 30.40 ± 4.8634 0.008
Phenylalanine 51.00 ± 13.35 37.35 ± 8.04 42.20 ± 15.85 42.00 ± 8.64 NS
Isoleucine 46.75 ± 13.60 32.7 ± 7.05 35.80 ± 8.20 39.50 ± 10.12 NS
Leucine 92.38 ± 22.63 65.1 ± 8.64 68.50 ± 16.13 70.35 ± 14.67 NS
Ornithine 41.50 ± 15.10 17.2 ± 5.143 16.10 ± 2.303 18.45 ± 4.883 0.003
Lysine 151.44 ± 44.40 106.35 ± 20.773 123.80 ± 19.734 125.00 ± 23.734 <0.001
Total 2482.2 ± 438.7 1652.75 ± 119.53 1572.4 ± 688.03 1794.1 ± 282.03 0.002
1

All values are means ± SDs.

2

Obtained by using Kruskal-Wallis one-factor ANOVA.

3

P < 0.05 compared with nonpregnant subjects (Mann-Whitney U test).

4

P < 0.05 compared with first trimester subjects (Mann-Whitney U test).

5

P < 0.05 compared with second trimester subjects (Mann-Whitney U test).