They are marketed as "one of pregnancy's essentials" but they could be death traps for the unwary, according to doctors.
Expectant parents are warned today not to use over-the-counter foetal heart monitors, the sales of which are rising rapidly. The fashionable devices cost from £20 to £90 and are advertised as enabling parents to listen to their baby's heartbeat at any time they choose. But their dangers are highlighted today by the case of a 34-year-old woman whose first baby was stillborn after she was falsely reassured that it was still alive by a foetal heart monitor that she was using at home.
The woman was 38 weeks pregnant and was fit and well when she turned up at the Princess Royal Hospital, Haywards Heath, Sussex, worried about her unborn baby.
The previous Friday she had noticed a reduction in her baby's movements but had her anxiety allayed by listening to the foetal heartbeat over the weekend.
However, when she arrived at the hospital after the weekend, an urgent ultrasound showed the baby was dead. Doctors say the most likely explanation for the mistake is that the mother either heard her own heart beat or the blood flow through the placenta and misidentified it as the baby's.
Writing in the British Medical Journal, they warn expectant parents not to deploy their own foetal heart monitors because of the risk they may give false reassurance and lead to delays in seeking medical help.
They cite an earlier case of a mother from Wirral, Cheshire, who also delayed getting help after she was falsely reassured by listening to what she believed was her baby's heart. In that case, reported in the BMJ in August, the baby survived but the delay in getting help and ensuring its delivery resulted in brain damage. The Wirral University NHS Trust now has posters in its antenatal areas recommending that women do not use these devices.
The researchers searched the web and found a large number of foetal heart monitors for sale, many without any warnings. The safety of the ultrasound devices is stressed, in that they do not harm the baby, but the real danger – a delay in seeking medical attention as a result of a misreading of the device – is not mentioned.
"Manufacturers and retailers have an obligation to make the limitations of these devices absolutely clear, as the untrained use of foetal heart monitors constitutes a risk to the safety of pregnant women and their unborn babies," they say.
The Medicines and Healthcare Regulatory Agency said it was concerned the devices were being increasingly used by the public. "Members of the public are unlikely to have the necessary knowledge or experience to use the device at home," the agency told the BMJ.
The Royal College of Obstetricians said it was a "cause of concern" if parents noticed a reduction in foetal movements but did not seek medical help and instead relied on a foetal heart monitor for reassurance.
However, a spokesman added that there were certain situations in which a monitor could be useful. "If an anxious parent sought medical advice before purchasing a monitor and had some element of training in how to use one by qualified staff, they could be of some use," he said.Reuse content