What it is and what it is used for

Cardiotocography - from the Greek tokos, birth, and graphein, to write - allows you to monitor fetal heart rate and uterine contractions . For this purpose, an apparatus called cardiotocograph is used, consisting of a central box and two probes placed on the mother's womb: the first is an ultrasound detector of the heartbeat (connected to the point where the perception of the heart is more high), while the second consists of a mechanical meter of uterine contractions (this pressure transducer is positioned lower down, in the area corresponding to the uterine fundus).

How do you do it?

Just as shown in the figure, both probes are fixed to the maternal abdomen using elastic bands. In this way, the data relating to fetal heart rate and uterine contractions, captured by the detectors, are transmitted to the central box of the cardiotocograph, which processes the electrical signals transforming them into tracks printed on video and / or on paper.

During cardiotocography, the pregnant woman can hear the heartbeat of the baby "live" thanks to an amplifier inside the device.

Are there risks to the fetus?

Cardiotocography is a completely painless and risk-free technique, both for the mother and the fetus; it generally lasts from 30 minutes to an hour, and can last longer if the baby is sleeping (during fetal life the alternation of the sleep-wake rhythm follows phases of about 40 minutes).

Heartbeat of the fetus

During pregnancy, the fetal heart rate normally fluctuates between 120 and 160 beats per minute, remaining constant only when the unborn child sleeps. Outside these limits, one speaks respectively of bradycardia and tachycardia. As the birth proceeds, the fetal heart rate tends to drop slightly, reaching 110 beats per minute at birth. In addition to the number of pulsations, monitoring of the magnitude and frequency of accelerations and decelerations of the heartbeat is particularly useful during cardiotocography.

The interpretation of the data collected during the examination, possibly facilitated by special software, is obviously up to specialized healthcare personnel.

When you run

In the last days of pregnancy (starting from the 38th week of gestation), cardiotocography is part of routine investigations; in fact, it is performed on an outpatient basis in order to detect any preparatory uterine contractions, and to check the normality of the fetal heartbeat. This monitoring starts early in the face of reduced fetal growth or when the woman is considered at risk because she suffers from particular disorders, such as gestational diabetes or gravidic hypertension.

During labor, cardiotocographic monitoring makes it possible to check whether the child is well resistant to the stress induced by uterine contractions, seizing any complications, such as hypoxia, that require cesarean section in the bud. This is the ultimate goal of cardiotocography, born with the clear objective of differentiating the physiological stress of labor from the actual "fetal suffering", characterized by signs of the fetus being unable to compensate for any hypoxic insult.

Unfortunately, the results were not up to the premise, so much so that even today there remain doubts about the real utility of cardiotocography, due to technical pitfalls, low specificity (high incidence of false positives, therefore high risk that healthy fetuses are falsely considered to risk) and other factors that may influence the information obtained or their interpretation.