The features of polyamine and amino acid metabolism play a key role in the cellular processes, and the search for their role as prognostic and diagnostic (assessment of fetal condition severity) markers in obstetrics can contribute to improvement of perinatal outcomes in fetal growth restriction (FGR) syndrome, both isolated and combined with early onset preeclampsia (PE). The study was aimed to determine the features of polyamine and amino acid levels associated with placentaassociated pregnancy complications. Liquid chromatography coupled with mass spectrometry was used to determine blood levels of polyamines and amino acids in 156 pregnant women divided into the following groups: with FGR — 48 pregnant women, with early onset PE — 56 pregnant women, control group — 52 somatically healthy women having no pregnancy complications. As a result, we managed to distinguish significant differences in these metabolites, depending on the obstetric complication (PE or FGR), and to determine correlations of those with a number of clinical data. We revealed a strong negative correlation between the increasing fetal condition decompensation in FGR and the length of the newborn’s hospital stay for the PE and FGR groups, as well as between the levels of 1,7-diaminoheptane polyamine (r = –0.78, CI = –0.92 – ‒0.37, p = 0.002; r = –0.76, CI = –0.95 – 0.23, p = 0.003) and proline amino acid and the increasing fetal condition decompensation in FGR (r = –0.56, CI = –0.86 – –0.034, p = 0.03). Considering the diversity and complexity of metabolic pathways responsible for adaptation in the context of hypoxic damage, the results obtained suggest that regulation of amino acids and polyamines is coordinated. Metabolic pathways of low molecular weight antioxidants, proline and polyamines, are associated with clinical pregnancy outcomes in FGR and early-onset PE.