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Test of vibroacoustic stimulation of the fetus
Last reviewed: 19.10.2021
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It is known that vibroacoustic stimulation causes a reaction from the fetus and can serve to assess its condition.
In normal pregnancy pregnancy test is always associated with the appearance of fetal movements, which the mother feels. The fetal response to stimulation is more active, the longer the gestation period. The test can be used as an initial screening of the fetus, but further studies with neurological and auditory control are needed to ensure that the method can be recommended in a broad clinical practice. It is important in this connection to consider the sound environment surrounding the fetus in the uterine cavity during childbirth. It is shown that in most women in childbirth their own cardiovascular noises are not monitored in the uterine cavity. The main intrauterine noises are low frequency sounds with a frequency below 100 Hz and a sound power of 60-85 dB. All maternal sounds in the uterine cavity (bowel movements, etc.) are well audited, reporting to the main intrauterine device. Intrauterine acoustic environment significantly changes in conditions of antenatal acoustical stimulation. Vibroacoustic stimulation with an artificial larynx apparatus with a sound power of 110 dB, a frequency of 60 Hz on average and a stimulation duration of 1-2 seconds in 1/3 of the fetuses causes tachycardia without significant differences in different periods of pregnancy.
Acoustic stimulation of the fetus in the early period of labor is performed to predict the further state of the fetus. Some authors believe that the vibro-acoustic stimulation test can replace the pH determination of the fetal head skin blood at threatening heart rate changes. It is important to consider the influence of vibroacoustic stimulation on the organization of behavioral reactions of the fetus. During the last third of pregnancy, the human fetus develops a gradual development of behavioral reactions. These reactions reflect the degree of maturity of the brain, they are similar in their manifestations to the reactions of the newborn. In fetuses with growth retardation, as well as in fetuses whose mothers suffer from type I diabetes, a delay in the development of behavioral reactions is observed. Normal fruits respond to vibroacoustic stimulation with motor reactions and prolonged tachycardia. The meaning of the behavioral reactions of the fetus is still not completely clear.