CTG and NST for Intrauterine Monitoring of Fetal Condition

The pregnancy is a wonderful yet sometimes worrying period during which expectant mothers and their families encounter numerous questions. Medical examinations, especially methods for monitoring fetal condition, play a key role during this time. One of the most important examination procedures is cardiotocography (CTG) and the non-stress test (NST), which allow us to track the fetal heartbeat and uterine activity. These methods are painless, safe, and can be performed multiple times during pregnancy if necessary.

Although CTG and NST examinations can be used as early as the beginning of pregnancy, the best opportunity to evaluate the information is later in the pregnancy. It is important for expectant mothers to be aware of these examinations and their significance, as they protect not only the baby’s health but also the mother’s.

What is the CTG and NST examination?

CTG, or cardiotocography, is a device that allows continuous monitoring of fetal heart rate and uterine muscle activity. During the examination, the device records two different curves: one shows the fetal heart rate, while the other indicates uterine activity. Based on this information, doctors can assess the fetal condition and oxygen supply. The characteristic of the CTG examination is that it also takes into account uterine contractions and fetal movements, thus providing a complete picture of the progress of the pregnancy.

The NST examination, on the other hand, works similarly but focuses only on the fetal heart rate. At this time, only one sensor is placed on the expectant mother’s abdomen, allowing the doctor to monitor the fetal condition even during labor. Both examinations are painless and extremely useful during pregnancy, especially if any risks arise, such as preterm labor or fetal distress.

How does the examination process take place?

NST and CTG examinations are completely safe and painless. These examinations can be performed by expectant mothers starting from the 24th week of pregnancy, but they are most recommended from the 36th week onward, when they are routinely used as part of prenatal care. In an uncomplicated pregnancy, performing the NST once a week is sufficient, while if the expectant mother has passed her due date, the examination is recommended every 1-2 days.

During the examination, the expectant mother sits or lies down, and the sensors attached to her abdomen monitor the fetal condition for 20-40 minutes. The data recorded by the sensors is printed on a paper strip, showing the changes in heart rate and uterine activity. During the NST, the expectant mother typically uses one sensor, while in the case of the CTG, two are placed to also consider uterine activity.

What can be read from the examination results?

The curves that appear during the CTG and NST examinations are extremely informative, as the fetal heart rate often reflects its condition. Doctors evaluate the baseline heart rate, oscillation, acceleration, and deceleration of the curve to gain insight into the fetal health. Under normal circumstances, the fetal heart rate ranges from 120-160 beats per minute.

If the heart rate is persistently elevated, it may indicate tachycardia, while a drop below 120 beats per minute is considered bradycardia, which can be a sign of oxygen deprivation. During fetal movement, the heart rate temporarily increases, and at least 2-5 such accelerations are needed during the examination for the curve to be reactive. If the curve does not show adequate activity, it may indicate oxygen deprivation, and further examinations may be necessary.

During the analysis of the curves, the variability of fetal heartbeats, i.e., the oscillation, is also an important factor. In a healthy fetus, variability is high, while in cases of oxygen deprivation, it may decrease, indicating a serious condition. Based on this information, doctors decide on further steps to ensure the health of both the fetus and the mother.

Stress Test CTG Examination and Alternative Methods

The stress test CTG examination is used less frequently, but it may become necessary if the curve is non-reactive and variability is reduced. In this case, the expectant mother performs light, non-strenuous exercises, such as stair climbing or stationary cycling, to activate the fetus. After the examination, the heart rate is re-evaluated to see if there is any change.

If there is no improvement after the stress test, further examinations may be necessary, such as flow studies to help uncover the fetus’s oxygen supply. Additionally, pharmacological stress, such as the administration of oxytocin, which promotes uterine contractions, may also be possible to help assess the fetal condition.

Screening Tests in Prenatal Care

The goal of prenatal care is to continuously monitor the health of the fetus and the mother. In Hungary, obstetricians, family doctors, and midwives collaborate in the care of expectant mothers. Basic examinations include ultrasounds, laboratory tests, genetic screenings, and gynecological check-ups.

Although mandatory screening tests are important, in certain cases, such as the expectant mother’s age or the detection of abnormalities, special tests may also be justified. These examinations help ensure that expectant mothers feel safe and confident that everything is going well during their pregnancy. Regular medical check-ups and appropriate examinations are therefore essential for a healthy pregnancy.