HON Mother & Child Glossary, Monitoring Foetal Heart Rate

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Reproduction

Procedure: Monitoring Foetal Heart Rate

The relation between foetal well-being and foetal heart rate has been investigated in numerous studies and it now seems clear that foetal distress may express itself in abnormalities of the heart rate (e.g. bradycardia , <120 beats/min; tachycardia , >160/min; reduced variability or decelerations).
There are two main methods of monitoring the foetal heart heart rate:

Intermittent auscultation . Here foetal heart rate is monitored with either the classic, monaural stethoscope (foetal stethoscope=foetoscope), or by a simple handheld ultrasound Doppler apparatus. The auscultation is usually performed once every 15-30 minutes during the first stage of labour , and following every contraction during the second stage .
Electronic foetal heart monitoring . Electronic monitoring is generally reserved for high-risk pregnancies, for babies whose presentation or position obscure their heartbeat from a stethoscope, or for babies whose heartbeat sounds abnormal through the stethoscope. The 2 main methods for continuous foetal heart monitoring are a) Externally via an ultrasound device attached to the mother's abdomen or b) Internally by inserting an electrode through the mother's vagina and attaching it to the foetus' scalp. The latter approach is reserved only for the most high-risk pregnancies where very specific information is needed and the membranes have ruptured .
Many doctors use one or another of these techniques for all deliveries because 30 to 50 % of babies who develop problems or die during delivery do so without warning. The major risk of this technique is that it seems it provokes a higher rate of caesarean sections . Also the method seems to produce a high rate of false positive signals, and a concomitant high number of thus, unnecessary interventions.