Two randomized controlled trials (RCT) on intrapartum fetal monitoring with cardiotocography (CTG) only versus CTG combined with automatic ST segment waveform analysis of the fetal ECG have been performed. In altogether 6826 randomized cases, the odds ratio for operative delivery for fetal distress (ODFD) was 0.65 (95% confidence interval 0.53-0.78) and for metabolic acidosis at birth 0.39 (0.21-0.72), in favor of the CTG+ST method. CTG combined with ST analysis increases the ability of obstetricians to identify fetal hypoxia and to intervene more appropriately, resulting in an improved perinatal outcome.