OBJECTIVE: To evaluate validity of biophysical diagnostic methods of fetal hypoxia. DESIGN: A case-control study. SETTING: Department of Gynecology and Obstetrics, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic. METHODS: We divided the patients according to pH in umbilical artery (UA) < 7.15 into two groups: controls (n = 36), and studied (n = 31), retrospectively. We performed continuous simultaneous fetal monitoring with cardiotocography (CTG), fetal pulse oxymetry (IFPO), and ST segment analysis of fetal electrocardiogram (STAN). STATISTICS: histograms, Kolmogorov-Smirnovov test, Mann-Whitney test, Spearman's rho; statistical significance: p < 0.05, Receiver Operating Characteristic curves, Area Under the Curve. RESULTS: The most frequent was intermediary CTG pattern (n = 32; 47.76%). Non-reassuring IFPO was in 22 cases (32.86%), and ST events were present in 4 cases (5.97%). CTG validity in prediction of pH in UA < 7.15: sensitivity 80.0%, specificity 50.0%, positive predictive value (PPV) 22.1%, and negative predictive value (NPV) 93.4%, respectively; IFPO sensitivity was 76.3%, specificity 71.4%, PPV 32.2%, and NPV was 94.4%. Validity of STAN was not significant, because of low frequency of ST events in our study. Satisfactory accuracy (AUC > 0.8) had combined continuous monitoring with CTG, IFPO and STAN. Good accuracy (AUC > 0.7) had CTG by itself, and combined monitoring with IFPO and STAN, respectively. IFPO by itself had only sufficient accuracy (AUC > 0.6). CONCLUSION: The most valid method of fetal wellbeing objectification is combined simultaneous monitoring with CTG, IFPO and STAN. Our results support the effort in the development of integrated sensor for CTG, IFPO, and STAN.