Evaluation of variable decelerations of fetal heart rate with the deceleration index: influence of associated abnormal parameters and their relation to the state and evolution of the newborn.

The deceleration index of the Fetal heart rate (FHR) (Acién P. et al. (1979) J. Perinat Med 7, 7-18) was used to analyze 157 cardiotocographic registers that displayed variable deceleration during labor. We have related the deceleration index value to perinatal results and to other abnormal parameters of FHR. An increase in neonatal pathology was observed in the deceleration group compared to a group of 50 controls with normal FHR, when the deceleration index was greater than 150 and specially if it was greater than 200. The association of other abnormal parameters of FHR (especially absence of variability between or during decelerations, absence of transitory ascents, presence of tachycardia and, of less importance, absence of ascents at the beginning of deceleration or presence of overshoot acceleration following deceleration) yields a worse prognosis for the fetus than does an increased deceleration index alone. The deceleration index is a good method for evaluation of variable decelerations of FHR, and is well correlated to the condition of the newborn.