Significance for fetal outcome of poor prognostic features in fetal heart rate traces with variable decelerations.

Objective: To determine the clinical significance of the existence of poor prognostic features in fetal heart rate (FHR) traces with variable decelerations.

Methods: This study was prospectively performed on 167 randomly selected women with a singleton pregnancy at term. Ninety-one patients had an FHR trace without pathological features. The remaining 76 women had variable decelerations and their FHR traces were analyzed carefully for the existence of poor prognostic features. Fetal and neonatal outcomes were compared in the normal and variable deceleration groups.

Results: There were statistically significant differences between the groups in 1 and 5 minute Apgar scores, fetal heart rate (FHR), umbilical artery blood pH, pCO2; whereas no significant differences were found in the levels of umbilical artery HCO3, pO2.

Conclusions: Prolonged deceleration had the highest specificity for 1 minute Apgar score < 7.5 minute Apgar score < 7 and umbilical artery blood pH < 7.20 (95.0%, 96.3%, 97.5%, respectively). Loss of variability during deceleration showed the highest specificity for the same fetal features (66.7%, 72.3%, 63.9%, respectively). All other poor prognostic features had high specificities but low sensitivities.