How fetal cardiotocography is performed

Fetal cardiotocography is an exam performed during pregnancy to check the baby's heartbeat and well-being, performed with sensors connected to the pregnant woman's belly that collect this information, being especially suitable for pregnant women after 37 weeks or in periods close to delivery.

This test can also be performed during labor to monitor the health of the baby at this time, in addition to assessing the woman's uterine contractions.

The fetal cardiotocography exam must be done in clinics or obstetrics units, which contain devices and doctors prepared for the exam, and costs, on average, R $ 150 reais, depending on the clinic and place where it is done.

How is done

To perform fetal cardiotocography, electrodes with sensors are placed on the tip, held by a type of strap over the woman's belly, which capture all activity inside the uterus, whether the baby's heartbeat, movement or contractions of the uterus.

It is an exam that does not cause pain or discomfort to the mother or the fetus, however, in some cases, when it is suspected that the baby moves little, it may be necessary to make some stimulus to wake him or shake him. Thus, cardiotocography can be done in 3 ways:

  • Basal: it is done with the woman at rest, without stimuli, just observing the patterns of movements and heartbeat;
  • Stimulated: it can be done in cases where it is necessary to assess whether the baby will react better after any stimulus, which can be a sound, such as a horn, a vibration from a device, or a doctor's touch;
  • With overload: in this case, the stimulus is made using medicines that can intensify the contraction of the mother's uterus, being able to evaluate the effect of these contractions on the baby.

The exam lasts about 20 minutes, and the woman sits or lies down, at rest, until the information from the sensors is registered on the graph, on a paper or on the computer screen.

When it is done

Fetal cardiotocography can be indicated after 37 weeks only for a preventive assessment of the baby's heartbeat.

However, it can be indicated in other periods in cases of suspicion of these changes in the baby or when the risk is increased, as in the following situations:

Risk conditions for pregnant womenRisk conditions in childbirth
Gestational diabetesPremature birth
Uncontrolled arterial hypertensionDelayed delivery, over 40 weeks
Pre eclampsiaLittle amniotic fluid
Severe anemiaChanges in contraction of the uterus during childbirth
Heart, kidney or lung diseasesBleeding from the uterus
Changes in blood clottingMultiple twins
InfectionPlacental abruption
Mother's age above or below recommendedVery long delivery

Thus, with this exam, it is possible to intervene as quickly as possible, in case changes are noticed in the baby's well-being, caused by asphyxiation, lack of oxygen, fatigue or arrhythmias, for example.

This assessment can be done at different periods of pregnancy, such as:

  • In the antepartum: it is done at any time after 28 weeks of gestation, preferably after 37 weeks, to assess the baby's heartbeat.
  • In the intrapartum: in addition to the heartbeat, it evaluates the baby's movements and the contractions of the mother's uterus during delivery.

The checks made during this exam are part of the set of assessments of fetal vitality, as well as others such as doppler ultrasound, which measures the blood circulation in the placenta, and the fetal biophysical profile, which takes several measures to observe the correct development of the baby. Learn more about the tests indicated for the third trimester of pregnancy.

How it is interpreted

To interpret the exam result, the obstetrician will evaluate the graphics formed by the sensors, on the computer or on paper.

Thus, in case of changes in the baby's vitality, cardiotocography can identify:

1. Changes in the fetal heart rate, which can be of the following types:

  • Basal heart rate, which may be increased or decreased;
  • Abnormal heart rate variations, which show fluctuations in the frequency pattern, and it is common to vary, in a controlled manner, during childbirth;
  • Accelerations and decelerations of heartbeat patterns, which detect whether the heartbeat slows down or accelerates gradually or abruptly.

2. Changes in the movement of the fetus, which may be reduced when it indicates suffering;

3. Changes in the contraction of the uterus, observed during delivery.

Usually, these changes occur due to the lack of oxygen to the fetus, which causes a decrease in these values. Thus, in these situations, treatment will be indicated by the obstetrician according to the time of pregnancy and the severity of each case, which may be with weekly monitoring, hospitalization or even the need to anticipate delivery, with a cesarean section, for example.