Expectant mothers may enjoy listening to their unborn babies' heartbeats, but they shouldn't rely on home fetal heart monitors to provide an accurate picture of fetal health, researchers say.
The devices may provide false reassurance in some situations, according to Dr. Abhijoy Chakladar of Princess Royal Hospital in West Sussex, England.
In the British Medical Journal, Chakladar reported a case in which a 34-year-old woman who was 38 weeks pregnant went to the emergency department because she couldn't hear her baby's heartbeat with her home fetal heart monitor.
A few days earlier, she said she had noticed that the baby was moving far less than usual. However, she reassured herself that everything was OK by listening to the monitor. A couple of days later, when she listened again, she couldn't detect anything and sought medical help.
Physicians performed an ultrasound and found no fetal heart activity. They gave the diagnosis -- intrauterine death -- but could not explain why it had happened.
All blood tests and infection screens were normal. There was no significant microbial growth from the placenta or fetus, and the fetus seemed morphologically normal, Chakladar said.
He said the stillbirth "may have been unavoidable," but listening to the fetal heart monitor "certainly delayed presentation to the hospital."
"Without training," he added, sounds heard on the monitor "could easily be misinterpreted." Likely, the mother had simply heard her own pulse or placental flow instead.
Chakladar said the risks of having a mother delay seeking medical attention -- as well as the limitations of some of the devices -- tend to be overlooked.
Home monitoring devices can give only a snapshot of the heart rate and "provide no indication of other important prognostic features," he said.
Medical professionals provide context that an untrained mother can't, he added. For example, midwives and obstetricians take careful histories and make experienced observations before making interpretations for a diagnosis.
But the sale and use of at-home fetal heart monitors has been on the rise, Rebecca Coombes, associate editor of BMJ, wrote in an accompanying editorial.
The devices are often sold over the Internet, making it hard for the U.K. Medicines and Healthcare Products Regulatory Agency -- which is responsible for regulating fetal monitors classified as medical devices -- to take disciplinary action.
But not all fetal heart monitors are medical-grade. Coombes said the regulated products use medical-grade ultrasound Doppler devices, which have to conform to medical standards and can cost $500 or more. But cheaper devices that do not use ultrasound retail for as little as $33.
"These are not considered medical devices," she said.
Chakladar said manufacturers and retailers have an obligation to make limitations like this "absolutely clear" to the consumer.
He also called on obstetric professionals to "educate expectant mothers about the limitations and consequences of untrained use of the devices."