Chapter 189 Fetal Heart Rate Testing: Bradycardia
INTRODUCTION
Description: Bradycardia is a decrease in the baseline heart rate (generally below 120 beats per minute [bpm]). Moderate bradycardia is generally defined as 80 to 100 bpm, and severe bradycardia as less than 80 bpm, for more than 3 minutes.
ETIOLOGY AND PATHOGENESIS
Causes: Depressed fetal oxygenation (placental dysfunction, abruption); fetal acidosis. Effects of maternal condition (hypotension, medication, position, significant hypothermia); congenital fetal heart block; paracervical block; head compression (during final descent of the fetus especially in the occiput posterior position).
