Fetal vibroacoustic stimulation for facilitation of tests of the wellbeing of the unborn baby

Acoustic stimulation of unborn babies may make tests on their wellbeing more effective.

Tests on unborn babies such as ultrasound, measuring the number of movements and the heart rate are carried out to check the baby’s wellbeing. As a baby's sleep periods can alter these results by making it non-reactive, various methods are used to wake the baby so that it can respond to the stimulus. Fetal vibroacoustic stimulation uses a hand-held electronic device placed just above the pregnant woman's abdomen. Brief sounds are sent through the mother’s abdomen to her baby. The vibroacoustic stimulation gives the opportunity to assess how the baby responds. Exposure of the baby to the vibroacoustic stimulation is generally considered safe but it can cause vigorous fetal movements and fetal distress. 

This review of 12 randomised controlled trials involving 6822 mothers found that vibroacoustic stimulation improved the effectiveness of the baby's heart rate testing. However, the data on fetal distress and perinatal death were too few to draw any conclusions on safety. More research is needed to determine the optimal intensity, frequency, duration and position of the vibroacoustic stimulation and to evaluate the safety and perinatal outcomes when used with cardiotocography and other tests of fetal wellbeing.

Authors' conclusions: 

Vibroacoustic stimulation offers benefits by decreasing the incidence of non-reactive cardiotocography and reducing the testing time. Further randomised trials should be encouraged to determine not only the optimum intensity, frequency, duration and position of the vibroacoustic stimulation, but also to evaluate the efficacy, predictive reliability, safety and perinatal outcome of these stimuli with cardiotocography and other tests of fetal wellbeing.

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Background: 

Acoustic stimulation of the fetus has been suggested to improve the efficiency of antepartum fetal heart rate testing.

Objectives: 

To assess the advantages and disadvantages of the use of fetal vibroacoustic stimulation in conjunction with tests of fetal wellbeing.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2013).

Selection criteria: 

All published and unpublished randomised controlled trials assessing the merits of the use of fetal vibroacoustic stimulation in conjunction with tests of fetal wellbeing.

Data collection and analysis: 

All review authors independently extracted data and assessed trial quality. Authors of published and unpublished trials were contacted for further information.

Main results: 

Altogether 12 trials with a total of 6822 participants were included. Fetal vibroacoustic stimulation reduced the incidence of non-reactive antenatal cardiotocography test (nine trials; average risk ratio (RR) 0.62, 95% confidence interval (CI) 0.48 to 0.81). Vibroacoustic stimulation compared with mock stimulation evoked significantly more fetal movements when used in conjunction with fetal heart rate testing (one trial, RR 0.23, 95% CI 0.18 to 0.29).

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