The modal fetal heart characteristics that prevail apart from periodic accelerations or decelerations associated with uterine contractions, is called baseline fetal heart activity25. Baseline fetal heart activity is described using the following characteristics- baseline fetal heart rate, beat-to-beat variability, fetal arrhythmia and distinct patterns such as sinusoidal or saltatory fetal heart rates.
The fetal heart rate is controlled by the autonomic nervous system. The vagus nerve has inhibitory influence on the heart rate and causes slowing of the heart rate. The sympathetic nervous system has excitatory influence on the fetal heart rate and causes an increase in heart rate. As the fetus approaches term, the influence of the …show more content…
Freeman34 et al concluded that bradycardia within the range of 80 to 120 bpm with good variability is reassuring. Causes of fetal bradycardia include congenital heart block and impending fetal compromise35,36
In a study by AL Tranquilli37 et al to quantify fetal bradycardia in the second stage of labor and to determine the correlation with neonatal acidemia, found significant correlation between increasing bradycardia in second stage of labor and decrease in neonatal pH. The diagnostic accuracy of the test was 73%. The PPV was found to be 78.5% and the NPV was 68.4%.
Another study by Yoshio Matsuda38 et al to predict fetal acidemia in placental abruption concluded that an abnormal FHR pattern, especially bradycardia is the most significant risk factor in placental abruption predicting fetal acidemia and is more valuable than ultrasound in predicting outcome in placental abruption during pregnancy.
In a study by J. T. Parer39 et al to find out an association between fetal acidemia and electronic fetal heart rate patterns a positive relationship was found between the degree of acidemia with bradycardia and the depth of