Listening in on progress of pregnancy

PHIL REID/The Dominion Post

ULTRA CAREFUL: Mum-to-be Bronwyn Gregory-Hunt has concerns about ultrasound, so is keen to try this wide belt that listens to foetal heartbeat.

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A Kiwi researcher has devised a non-invasive way to measure foetal heartbeats that could provide an alternative to ultrasound.

The device uses sophisticated microphones embedded in a wide belt to listen for both the mother and the unborn baby's heartbeats.

The infant's heartbeat is then isolated from the mother's and from background noise using a technique called blind source separation.

The new system, tentatively called Pam (passive acoustic monitoring), was less invasive than ultrasound, said Dr Paul Teal of Victoria University. "This is more like using the Pinard, the foetal stethoscope that midwives used before the invention of ultrasound, but it's much more reliable and easy to use."

He said most clinicians believed ultrasound was safe, but anecdotal evidence suggested that many mothers did not like it, because it put energy into their bodies.

"Many midwives report that babies aren't too keen on it either."

Mum-to-be Bronwyn Gregory-Hunt said she would be keen to use the device. Concerns over ultrasound meant that she did not have scans unless they were deemed necessary by her midwife.

"They call it ultrasound but I'm not sure how ultra it is for the baby."

Dr Teal is working with Wellington midwives to collect data from mothers using a prototype Pam device.

It is hoped Pam will be able to detect an unborn baby's heartbeat from 18 weeks.

"Ultrasound can work from about 12 to 14 weeks, but the important stages are later in the pregnancy," he said.

The heartbeat of an unborn baby can give clues to its health and be monitored during birth.

Wellington midwife Suzanne Miller said the prototype was hard to use compared to ultrasound because it was not hand-held. "But if it can be made smaller, I think we would be excited at the possibility."

She said many pregnant women would welcome the chance to avoid ultrasound. "It's never been proven to be a danger, but it's never been disproved either.We tend to use it as little as possible."