The CTG during pregnancy and childbirth

The comprehensive during pregnancy often include the CTG. But what kind of device are you actually connected to, and how does it work? Why is it so important, and what do the curves recorded by the CTG indicate? In this article, we have summarized and answered the most important questions about this examination for you.

What is an CTG?

The abbreviation CTG stands for Cardiotocogram / Kardiotokogram. With the help of the CTG, your midwife or your gynecologist/obstetrician measures the contractions and the heartbeat of your baby. This is done using two different sensors attached to your abdomen with straps: an ultrasound sensor that measures your baby's heart rate using ultrasound signals (the cardiograph), and a pressure sensor (the tocograph) that detects changes in abdominal circumference and thus the strength and frequency of contractions, if any are present. By measuring the heartbeat, the CTG also allows an assessment of your baby's oxygen supply. The examination is painless and safe for both mother and baby.

When is a CTG performed?

If your pregnancy proceeds without complications, your gynecologist usually only performs the three mandated . Because since last year, a reorganization in statutory prenatal care states that in uncomplicated pregnancies, no more CTGs are required during check-ups until the due date. According to the new guidelines, a CTG is only necessary in the following abnormalities:

• If a premature birth is imminent before the 28th week of pregnancy

• In case of premature labor or suspicion thereof

• During bleeding

• In case of abnormalities in Doppler ultrasound (special ultrasound examination of the vascular supply)

• In multiple pregnancies

• In case of too much or too little amniotic fluid

• Suspected of placental insufficiency

• When taking labor suppressants

• In the event of past miscarriages

• In case of overdue pregnancy (from the 40th week of pregnancy )

Technically, the CTG is possible from about the . Shortly before and during the , the CTG then becomes important for every pregnant woman: Usually, you will be connected to the CTG immediately upon arrival at the delivery hospital to monitor contractions and your baby's well-being. (During labor, a CTG is performed approximately every two hours.)

How does a CTG examination proceed?

During the CTG, you sit or lie in a quiet room. One or two belts are placed around your abdomen, with the sensors of the CTG attached to them. These are connected to a monitor via a cable. One sensor, the Tocograph, responds to the changing tension of your abdominal wall caused by pressure changes in your uterus, thereby measuring the contraction activity. The other sensor, the Cardiograph, sends ultrasound signals through your abdomen, which are then reflected by your baby's heart. It records the time between two heartbeats and calculates the number of heartbeats per minute, i.e., your baby's heart rate.

Why is a CTG examination important?

The CTG allows for the early detection of complications during pregnancy. If the CTG values deviate from the normal range, it may indicate restricted or poor blood flow to the baby or a threatened preterm birth. (During delivery, the CTG can also indicate umbilical cord blood or oxygen deprivation or a nuchal cord with the .) The earlier these complications are identified, the better your doctor can intervene and provide the best possible help for you and your baby.

What do the CTG values/-curves mean?

During the CTG, two or four values are recorded on a long paper strip. In our image, you see the version with two values. The upper curve represents the baby's heart rate. Normally, values between 120 and 160 beats per minute are observed here. However, there can also be completely harmless deviations, for example, if your baby is moving a lot or sleeping. During labor, this curve can also be read to see how your baby reacts to the . When the uterus contracts during a contraction, less blood reaches the baby, and its heartbeat slows down for a short moment. After the contraction, the heartbeat normalizes again.

The lower curve in the example image shows the contractions. The strong fluctuations of the line each represent a contraction; the curve depicts the duration and frequency of the contractions. It is possible that the CTG records contractions that you do not feel at all, because the sensor is very sensitive. The recording of the contractions is also called the Toco value.

Modern CTG devices can also record fetal movements, which would otherwise only be visible in ultrasound. This third value then appears as small, vertical lines on the paper strip. Perhaps your doctor also asks you to press a button or notify them when you feel your baby's movements yourself. This is the fourth value and is also marked with small, vertical lines.

The FIGO score

Your doctor will then evaluate the CTG values based on the so-called FIGO score. The heart rate of your baby will be assessed using the following four criteria:

• Base frequency: How many heartbeats per minute were recorded?

• Bandwidth: Does the heart rate fluctuate?

• Deceleration: Does the heart rate slow down regularly?

• Acceleration: Does the heart rate regularly increase?

These criteria are evaluated individually and then contextualized within the overall course of pregnancy and childbirth. This allows for a quick and accurate assessment of the baby's condition, which additional examinations are necessary, and when prompt intervention should be taken.

In any case, your doctor will talk to you about everything and explain the measures. Also ask any questions that may come up for you. This way, you can perhaps dispel many worries. The CTG helps to monitor your pregnancy and ensure that your baby is doing well. So you can also be reassured and discuss any emerging concerns and directly with your doctor. This is to make the pregnancy period as pleasant and beautiful as possible for you and your baby.