The correlation between total deceleration and acceleration surface areas on electronic fetal monitoring and neonatal cord blood pH in postdate pregnancies.

OBJECTIVE: To assess the correlation between the total decelerations area in the final 120 min before delivery and neonatal cord blood pH in postdate pregnancies. METHODS: This cross-sectional study included women with gestational age greater than 41 weeks, singleton pregnancy, and a category II electronic fetal monitoring (EFM) of at least 30 min during the final 120 min before delivery. We included postdate deliveries of an otherwise low-risk parturient population. Each area was calculated as duration × depth × 1/2. Correlations were tested using the Spearman correlation coefficient. RESULTS: A total of 100 EFMs were included in the analysis. Median pH was significantly lower in neonates above the median total deceleration area under the curve (AUC; 7.26 vs. 7.32, P = 0.002). Gestational age at delivery was independently associated with total deceleration AUC above median (adjusted odds ratio 1.21, 95% confidence interval 1.09-1.37) controlling for history of previous cesarean delivery and duration of second stage of labor. A significant correlation was found between cord blood pH and total deceleration area (P < 0.001, Spearman correlation coefficient -0.37). CONCLUSION: Among women with postdate pregnancies, the total deceleration area and the mean maximum duration of decelerations were negatively correlated with cord blood pH. Further studies are needed to incorporate deceleration area as a method in predicting fetal acidemia.