Fetal Heart Rate Patterns in Labour and the Risk of Neonatal
Encephalopathy: A Case Control Study
Abstract
Objective To determine the accuracy of intrapartum fetal heart rate
(FHR) abnormalities as defined by National Institute of Health and Care
Excellence guidelines for the prediction of moderate-severe
hypoxic-ischemic neonatal encephalopathy (HIE). Design Case-control
study Setting Rotunda Hospital, Dublin, Ireland. Population or Sample
Eligible babies were born between September 2006 and November 2017 at
≥35+0 weeks’ gestational age. Cases were eligible babies with
moderate-severe HIE. Controls were eligible babies born before and after
each case with normal Apgar scores. Methods Blinded manual marking of
FHR trace features followed by automated categorisation of each
15-minute segment. Main Exposure Measures FHR pattern features:
baseline, variability, accelerations, early, variable, deep/prolonged
variable, late or prolonged decelerations, bradycardia, sinusoidal
pattern FHR pattern categories: normal, suspicious, or pathological
Results Adequate FHR traces results were available in 52 of 88 cases and
118 of 176 controls. The FHR pattern feature with the largest area under
the receiving operator characteristic curve (AUROCC) was the maximum
number of consecutive segments with the baseline >160bpm
(0.71 [95% confidence interval {CI}: 0.62-0.80]). The FHR
category variable with the highest AUROCC was the number of suspicious
segments (0.76 [95% CI: 0.67-0.84]). A multivariate model
incorporating the number of segments and the percentage of segments
classed suspicious/pathological achieved an AUROCC of 0.782 (95% CI:
0.704-0.861). Conclusions The power of FHR analysis to predict HIE is
hampered by poor sensitivity for the rarity of the outcome. When
analysing a suspicious FHR trace, it is beneficial to consider the
overall duration of the suspicious patterns