Dangers of listening to the fetal heart at homeBMJ 2009; 339 doi: http://dx.doi.org/10.1136/bmj.b4308 (Published 06 November 2009) Cite this as: BMJ 2009;339:b4308
- Abhijoy Chakladar, research fellow,
- Hazel Adams, consultant
- 1Department of Anaesthesia, Princess Royal Hospital, Brighton and Sussex University Hospitals NHS Trust, Haywards Heath, West Sussex RH16 4EX
- Correspondence to: A Chakladar
The fetal heart rate is commonly measured on the labour ward and during pregnancy to monitor the health of the fetus. It requires training and skill to perform accurately. Over the past few years fetal heart monitors have been marketed to expectant parents who want to hear their baby’s heartbeat. However, if not used properly these devices can provide false reassurance, as our recent case describes.
A 34 year old woman presented urgently to our labour ward on a Monday unable to detect her baby’s heartbeat with her fetal heart monitor. She was 38 weeks pregnant with her first baby and was fit and well, with no medical history. Screening blood tests, fetal anomaly, and subsequent growth scans had shown no abnormalities. The preceding Friday she had noticed a reduction in fetal movements but had reassured herself by listening to the “fetal” heartbeat over the weekend. An urgent ultrasound scan showed no fetal heart activity and intrauterine death was diagnosed.
We assumed the patient had been listening to her own pulse or placental flow. We found no reason for the stillbirth. All blood tests and infection screens from the mother gave normal results. There was no significant microbial growth from the placenta or fetus, and the fetus seemed morphologically normal. Histopathological analysis of the placenta found nothing unusual.
There has been another recent case of false reassurance with a home fetal heart monitor.1 Although the baby did not die, it required a long stay in the neonatal intensive care unit and had serious neurological morbidity.
After the experience in our obstetric unit, we conducted an internet search and were surprised by the number of fetal heart monitors available. There are two main types: sound amplifiers and Doppler ultrasound devices. A high street pharmacy and a large toy retail chain stock a prenatal listening (amplifying) system that claims to be “easy and safe to use to hear your unborn baby’s heart beat.” However, without training the sounds detected could easily be misinterpreted. Although potential purchasers on the pharmacy’s website are cautioned that “it is not a medical device and should not replace medical supervision,” the toy chain’s website gives no such advice. Other internet retailers are not so reserved (www.dopplerhire.com), suggesting that Doppler devices can be used for reassurance in between hospital visits and scans. The safety of the Doppler ultrasound devices is stressed, in that they do no harm to the baby, but the risks of delaying seeking medical attention and the limitations of Doppler devices tend to be overlooked.
Movements can vary considerably from fetus to fetus and at different times of the day. A recent Cochrane review noted that there was not enough published evidence to support fetal movement as a marker of fetal wellbeing.2 Nevertheless, our obstetric unit, like most, encourages expectant mothers to present to the labour ward for assessment if fetal movements reduce.
The normal fetal heart rate ranges between 110 and 160 beats per minute with a baseline variability of 5 beats per minute. On the labour ward, the fetal heart rate is usually measured over time with an electronic fetal monitor, which gives a paper trace, and is interpreted by experienced midwives and obstetricians. Any decisions on fetal health are made only after taking careful histories of the events leading to presentation, examination, and consideration of the wider clinical context. Home monitoring devices can give only a snapshot of the heart rate and provide no indication of other important prognostic features.
The intrauterine death in our case may have been unavoidable, but the use of a fetal heart monitor certainly delayed presentation to hospital. Manufacturers and retailers have an obligation to make the limitations of these devices absolutely clear, as the untrained use of fetal heart monitors constitutes a risk to the safety of pregnant women and their unborn babies. The risk will undoubtedly increase as these devices become more popular. The use of home monitors may also result in women unnecessarily referring themselves to general practitioners and obstetric units when they cannot hear the fetal heart because of inexperience. We asked the retailers how many devices they had sold or hired out but received no reply.
Obstetric services need to educate expectant mothers about the limitations and the potentially fatal consequences of untrained use of fetal heart monitors and to present clear guidance about when to seek medical review.
Cite this as: BMJ 2009;339:b4308
Competing interests: None declared.
This case has been reported to the National Patient Safety Agency.
Patient consent obtained.
Provenance and peer review: Not commissioned; externally peer reviewed.