Table 1. Molecules whose concentration (mM, mean ± SD) showed significant differences between the first and the second trimester of pregnancy.

	First trimester (mM; mean ± SD)	Second trimester (mM; mean ± SD)	P value	Variation
Adenine	0.011 ± 0.007	0.014 ± 0.008	0.002	↑
Tryptophan	0.0091 ± 0.002	0.0099 ± 0.002	0.01	↑
Benzoate	0.0034 ± 0.001	0.0029 ± 0.0009	0.003	↓
Phenylalanine	0.027 ± 0.013	0.034 ± 0.012	< 0.0001	↑
Phenylpropionate	0.035 ± 0.015	0.042 ± 0.012	< 0.0001	↑
Tyramin	0.008 ± 0.01	0.005 ± 0.009	0.01	↓
Hydroxyphenylacetate	0.023 ± 0.01	0.026 ± 0.007	0.02	↑
Inosine	0.0048 ± 0.002	0.0042 ± 0.002	0.03	↓
UDP	0.013 ± 0.003	0.014 ± 0.003	0.002	↑
Uridine	0.009 ± 0.005	0.008 ± 0.004	0.001	↓
Maltose	0.20 ± 0.12	0.15 ± 0.11	< 0.0001	↓
Threonine	0.054 ± 0.018	0.062 ± 0.018	0.001	↑
Lactate	2.39 ± 0.87	2.63 ± 0.80	0.002	↑
Serine	0.067 ± 0.039	0.078 ± 0.030	0.04	↑
Glycine	0.071 ± 0.024	0.090 ± 0.023	< 0.0001	↑
Glucose	0.056 ± 0.051	0.044 ± 0.035	0.01	↓
sn-Glycero-3-phosphocholine	0.009 ± 0.004	0.008 ± 0.004	0.002	↓
Creatinine	0.017 ± 0.011	0.013 ± 0.009	0.005	↓
Creatine	0.024 ± 0.008	0.028 ± 0.009	0.0003	↑
Aspartate	0.023 ± 0.009	0.026 ± 0.008	0.001	↑
Methylamine	0.0024 ± 0.004	0.0011 ± 0.001	< 0.0001	↓
Glutamine	0.028 ± 0.01	0.034 ± 0.01	< 0.0001	↑
Glutamate	0.26 ± 0.10	0.33 ± 0.08	< 0.0001	↑
5-Aminopentanoate	0.025 ± 0.02	0.026 ± 0.02	< 0.0001	↑
Methionine	0.009 ± 0.005	0.013 ± 0.006	< 0.0001	↑
Acetate	0.61 ± 0.73	0.46 ± 0.66	0.01	↓
Putrescine	0.007 ± 0.01	0.005 ± 0.01	0.04	↓
3-Hydroxyisovalerate	0.0014 ± 0.0004	0.0016 ± 0.0005	0.003	↑
Ethanol	0.036 ± 0.031	0.025 ± 0.017	0.003	↓
Propionate	0.026 ± 0.04	0.023 ± 0.07	< 0.0001	↓
Isoleucine	0.021 ± 0.01	0.026 ± 0.01	< 0.0001	↑
Valine	0.029 ± 0.01	0.031 ± 0.01	0.03	↑
Leucine	0.099 ± 0.04	0.12 ± 0.04	< 0.0001	↑

Differences were searched by Wilcoxon matched-pairs signed rank test and a P value < 0.05 was considered as significant.