Atypical decelerations: do they matter?

Abstract

Objective: To estimate the association between atypical variable decelerations and neonatal acidemia.Method: We conducted a one-year case-control study comparing the last thirty minutes before delivery of fetal heart rate tracings of 102 acidemic neonates (umbilical arterial cord gas pH ≤ 7.10) with 100 non-acidemic controls (umbilical arterial cord gas pH > 7.10). Incidence of atypical features and total number of decelerations, number of atypical decelerations, number of slow return decelerations and number of decelerations with loss of moderate variability during deceleration were extracted. We estimated the association between atypical features, neonatal acidemia and neonatal morbidity.Results: Acidemic neonates showed a larger number of atypical decelerations (4 [0-12] vs. 3 [0-10]), “slow return” decelerations (4 [0-11] vs. 1 [0-10]) and decelerations with non-moderate variability (0[0-12] vs. 0 [0-6]) compared to non-acidemic controls. “Slow return” was significantly associated with an increased risk of acidemia at birth (OR 4.46; CI 95%: 2.18 – 9.15) “Slow return” was the most discriminating feature between groups with an AUC: 0.745.Conclusion: Certain atypical features, as “slow return” and loss of moderate variability within decelerations are associated with neonatal acidemia. “Slow return” could help in the gradation of acidemia risk levels, as an indicator of gravity.