Why you shouldn’t use a fetal doppler at home when you’re pregnant

What is a fetal doppler and why are they dangerous?

Dopplers are small, battery-operated devices that send out high-frequency ultrasound waves. There's usually a handset, a built-in speaker and a transducer that's placed against your bump.

The ultrasound waves pass through your skin and tissue and then bounce back, before being translated into sound. It's a similar process to being scanned in pregnancy but instead of pictures, it's sound.

Although dopplers seem harmless, health professionals warn that these devices are increasing the risk of stillbirths.

Instead of going straight to hospital when they're worried about their babies, mothers are using dopplers to check their baby’s heartbeat - but these devices are very unreliable when not used by a trained professional.

When using one, it’s easy to mistake your own heartbeat and the pulsing of the placenta for the baby’s heartbeat. This means that when you listen in, you may not be hearing the baby’s heartbeat at all and can be falsely reassured.

Hearing a heartbeat is not a reliable way to tell if a baby is well. Instead, monitoring changes in movements and reporting any reduction immediately is the best way to be safe. Feeling a baby move during pregnancy is a good sign, but if the baby moves less, it can be an important warning sign that the baby isn’t well.

Professor Alexander Heazell, professor of obstetrics and director of the Tommy's Stillbirth Research Centre at the University of Manchester, has found that more women are coming into hospital too late after feeling their babies move less.

Recently, he says, two babies died by the time their mothers were seen by a medical team.

“There’s little regulation for the development, testing and marketing of apps and devices sold for home use and it’s hugely concerning to find some people rely on them for the safety of their baby,” he says.

“Even if you detect a heartbeat it does not mean that a baby is necessarily well. It is important that if you are concerned about your baby’s wellbeing, you act as quickly as possible if you notice a change.”

The pregnancy charity Tommy’s is urging expectant parents to seek advice from a medical professional immediately if they notice any changes in their baby’s movement.

You should start to feel your baby move between around 16 to 24 weeks of la grossesse, but if this is your first baby, you might not feel movements until 20 weeks or after. If you haven’t felt your baby move by then, speak to your midwife - they will be able to check your baby’s heartbeat and movements. You should feel your baby move right up to and during labour.

You don’t need to count the number of exact kicks or movements, but it can help to get to know your baby’s normal movements throughout the day. They may get into a pattern, for example, moving more after you’ve eaten or in the morning or evening.

Elizabeth Hutton is the chief executive of Kicks Count, a baby movement resource and awareness campaign.

"The false reassurance using dopplers gives is our concern. If you saw a person collapsed in the street would you check their pulse and walk away? No, you’d probably call an ambulance because this person is clearly unwell, even though they have a heartbeat. It is the same with a baby," she says.

"If a baby’s movements change, it can be a sign that they are unwell. All a heartbeat tells you is the baby is currently alive, which is the only time something can be done to help a baby in distress. If you wait until you can’t find a heartbeat it’s too late.