Vibroacoustic stimulation for fetal assessment in labour in the presence of a nonreassuring fetal heart rate trace

Vibratory and sound stimulation may help to tell how well a baby is during labour when the heart beat is showing possible concerns.

A baby's heart rate is checked during labour to try to identify babies who are having difficulties. However, changes in the baby's heart-rate patterns may not always mean the baby really is having difficulties. When the heart-rate pattern is not reassuring, extra tests may help to indicate which babies need help. Sound and vibratory stimulation (fetal vibroacoustic stimulation) is one such test. For healthy babies it produces a positive response, and absence of this could be a sign that the baby is having difficulty. The review authors found no randomised trials that considered vibroacoustic stimulation for this use. More research would be helpful.

Authors' conclusions: 

There are currently no randomised controlled trials that address the safety and efficacy of VAS used to assess fetal well-being in labour in the presence of a nonreassuring CTG trace. Although VAS has been proposed as a simple, non-invasive tool for assessment of fetal well-being, there is insufficient evidence from randomised trials on which to base recommendations for use of VAS in the evaluation of fetal well-being in labour in the presence of a nonreassuring CTG trace.

Read the full abstract...

Fetal vibroacoustic stimulation (VAS) is a simple, non-invasive technique where a device is placed on the maternal abdomen over the region of the fetal head and sound is emitted at a predetermined level for several seconds. It is hypothesised that the resultant startle reflex in the fetus and subsequent fetal heart rate (FHR) acceleration or transient tachycardia following VAS provide reassurance of fetal well-being. This technique has been proposed as a tool to assess fetal well-being in the presence of a nonreassuring cardiotocographic (CTG) trace during the first and second stages of labour.


To evaluate the clinical effectiveness and safety of VAS in the assessment of fetal well-being during labour, compared with mock or no stimulation for women with a singleton pregnancy exhibiting a nonreassuring FHR pattern.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (6 September 2012) and reference lists of all retrieved articles. We sought unpublished trials and abstracts submitted to major international congresses and contacted expert informants.

Selection criteria: 

All published and unpublished randomised trials that compared maternal and fetal/neonatal/infant outcomes when VAS was used to evaluate fetal status in the presence of a nonreassuring CTG trace during labour, compared with mock or no stimulation.

Data collection and analysis: 

Two review authors independently sought to assess for inclusion all the potential studies we identified as a result of the search strategy. We planned to resolve any disagreement through discussion or, if required, to consult a third person. Where there was uncertainty about a particular study, we attempted to contact study authors for additional information. However, these attempts were unsuccessful.

Main results: 

The search strategies yielded six studies for consideration of inclusion. However, none of these studies fulfilled the requirements for inclusion in this review.