Long-term Bioeffects of Prenatal Doppler Ultrasound Exposure and the Relation to Genetic Defects of the Fetus in Utero

Cardiotocography, fetal heart rate contraction recording, refers to a method for the simultaneous registration and recording of the heart rate of the unborn child and the uterine contractions in the expectant mother. The procedure is used both in pregnancy care and during labor. The fetal heart rate is usually determined using pulsed-wave Doppler ultrasound and recorded in beats per minute. The mother's uterine contractions are simultaneously recorded using a separate uterine contraction sensor, a pressure gauge. There are two methods for this: the rarely used intrauterine direct pressure measurement, which can only be used after the amniotic sac has opened, i.e., during labor, and the more common external pressure measurement using a tocodynamometer. This differential pressure gauge responds to changes in abdominal tension during a contraction, leading to large individual fluctuations in the recording of uterine contractions. The interpretation of a CTG or the calibration of the device must therefore take into account the constitution of the pregnant woman and her reports of the palpability of contractions. The course of changes in the fetal heart rate is interpreted taking into account the uterine contractions and the gestational age in pregnancy care or the progress of labor. In cases of suspected inadequate fetal oxygenation and uteroplacental dysfunction, a contraction stress test with CTG monitoring can be performed. It has many false-positive results and is no longer recommended in the current S3 guideline for vaginal delivery from 2022 and could have pathological influence developing autism spectrum disorder in childhood. Recent studies hypothesis that intermittent fetal heart rate contraction recording could have influence on genetical architecture structure of the fetus in utero.