Heart Sounds | Which CTG values are normal?

Heart Sounds

With the help of the child’s heart sounds, the heart rate of the unborn child can be determined during a cardiotocogram (CTG). This is done technically using a Doppler ultrasound, from which a signal is emitted and the time is measured until the signal is reflected by the child’s heart and reaches the sensor again.From this period of time, it can then be calculated how fast the child’s heart activity is currently. The measurement sensor is usually a special microphone, also known as a Doppler ultrasound transducer.

The advantage of this method is certainly that a “live” monitoring of the child from the outside can be carried out by a completely non-invasive procedure. However, due to the indirect measurement, the procedure as a whole is also particularly susceptible to the smallest disturbances, such as movements of the child or the mother. It is therefore important to perform a CTG examination continuously for at least half an hour in order to obtain a meaningful overall view.

Ideally, the mother should also lie as still and relaxed as possible and not move much during the examination. In most cases, this examination is not performed until the 30th week of pregnancy. It is usually repeated every 14 days until the actual date of birth if there are no further abnormalities within the scope of the usual preventive examinations.

By default, this examination should be performed during childbirth in all women. In principle, the CTG is more useful for monitoring advanced pregnancy or the birth process. In the case of imminent premature birth or risk constellations of the mother such as diabetes mellitus, high blood pressure, infections, vaginal bleeding or abnormalities of the child in the ultrasound scan, a CTG examination should be performed as early as the 25th week of pregnancy.

If the unborn child is transferred, i.e. if the pregnancy continues after the calculated delivery date, the CTG examination should be repeated at shorter intervals. Before the birth itself, a cardiotocogram (abbreviated: CTG) is routinely carried out in order to better monitor the infant’s condition before birth. The main purpose of this examination is to measure the child’s reaction to the contractions and whether he or she is properly prepared for the upcoming birth. Usually a 30-minute CTG is then recorded every two hours. If there are indications of an imminent danger to the child in the womb, the CTG examination can be carried out for a longer period of time, possibly even continuously until birth.