Thyroid, Breast, Endocrine & Cancer Surgeon
Obstetrician, Gynecologist & Laparoscopic Surgeon
Cardiotocography (CTG) measures your baby's heart rate. At the same time it also monitors the contractions in the womb (uterus). CTG is used both before birth (antenatally) and during labour, to monitor the baby for any signs of distress. By looking at various different aspects of the baby's heart rate, we get information about how the baby is coping.
Equipment used to monitor the baby's heart is placed on the tummy (abdomen) of the mother. An elastic belt is placed around the mother's abdomen. It has two round plates about the size of a tennis ball which make contact with the skin. One of these plates measures the baby's heart rate. The other assesses the pressure on the tummy, and in this way is able to show when each contraction happens and an estimate of how strong it is.
The CTG belt is connected to a machine which interprets the signal coming from the plates. The baby's heart rate can be heard as a beating or pulsing sound which the machine produces. The machine also provides a printout which shows the baby's heart rate over a certain length of time. It also shows how the heart rate changes with your contractions.
If you have CTG before you are in labour you may be asked to press a button on the machine every time the baby moves. At this time you will not be having any contractions so the CTG will only monitor the baby's heart rate.
CTG uses sound waves called ultrasound to detect the baby's heart rate. Ultrasound is a high-frequency sound that you cannot hear, but it can be sent out (emitted) and detected by special machines.
In CTG monitoring, a special type of ultrasound, called Doppler, is used. This type of ultrasound is used to measure structures that are moving, making it useful for monitoring heart rate.
It is normal for a baby's heart rate to vary between 110 and 160 beats a minute. This is much faster than your own heart rate, which is about 60-100 beats per minute. A heart rate in your baby that doesn't vary or is too low or too high may signal a problem.
In a normal, low-risk delivery, CTG is not usually needed.However, in certain situations, continual monitoring with CTG is advised. These include:
⇒ Your baby is coming early or seems smaller than expected.
⇒ You have high blood pressure.
⇒ You have a high temperature
⇒ You pass fresh blood whilst in labour.
⇒ You are expecting twins.
⇒ The baby has opened its bowels (passed meconium) into the amniotic fluid.
⇒ You have an epidural for pain relief.
⇒ You have labour speeded up with Syntocinon®.
⇒ CTG does not use any radiation; it is considered a very safe test. Depending on the machine used, it may prevent you from being able to move around freely during labour.