Evaluation of fetal heart rate patterns during the second stage of labor through fetal oximetry.

The purpose of this study was to assess the feasibility and accuracy of fetal pulse oximetry during the second stage of labor in cases with abnormal fetal heart rate (FHR) patterns with reference to postpartum acid-base status and Apgar scores. Forty-eight parturients with normal and 20 parturients with abnormal FHR tracings during the second stage of labor were monitored by fetal pulse oximetry and postpartum umbilical artery pH, pO(2), pCO(2) values and 1- and 5-min Apgar scores. The mean SpO(2) value was 55. 47 +/- 9.95% in cases with normal and 52.55 +/- 16.42% in cases with abnormal FHR patterns. A significant correlation was noted between fetal SpO(2) and umbilical artery pH in cases with normal (r = 0.76, p < 0.05) as well as in cases with abnormal FHR patterns (r = 0.78, p < 0.05). No significant correlation was found between fetal SpO(2) and Apgar scores at 1 and 5 min in cases with normal FHR patterns. On the contrary a significant correlation was noted in cases with abnormal FHR patterns. A normal FHR pattern alone is reassuring. In cases with abnormal FHR, fetal pulse oximetry is an objective method for distinguishing a hypoxic fetus.