Influence of maternal hypotension on umbilical artery pH in parturients undergoing cesarean section

Summary : Purpose: Maternal hypotension may cause fetal acidosis following a decrease in uteroplacental blood flow. However, few studies have targeted the influence of prolonged maternal hypotension on umbilical artery pH. We investigated the influence of the magnitude and duration of maternal hypotension on umbilical artery pH in parturients undergoing cesarean section. Methods: We performed a retrospective observational study of 423 patients who underwent scheduled cesarean section under spinal and epidural anesthesia. Data regarding blood pressure, umbilical pH, and Apgar score were obtained from anesthesia records or hospital records. We examined the correlation between shock index just before delivery and the umbilical artery pH. Patients were then divided into two groups depending on the duration of hypotension: within 10 minutes and longer than 10 minutes. We compared the umbilical artery pH between the two groups. Results: Umbilical artery pH showed no association with shock index just before delivery. Mean arterial pressure < 70 mmHg, ≥ 10 minutes was not a risk factor for fetal acidosis (umbilical artery pH 7.304 ± 0.050 at < 10 minutes vs. 7.297 ± 0.045 at ≥ 10 minutes, P = 0.163). Similarly, systolic blood pressure < 100 mmHg, ≥ 10 minutes was not a risk factor (umbilical artery pH 7.303 ± 0.050 at < 10 minutes vs. 7.300 ± 0.045 at ≥ 10 minutes, P - 0.494). Conclusion: Prolonged maternal hypotension did not affect the fetal umbilical artery pH at cesarean section.