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A Cheap, Portable Way to Monitor Unborn Babies

A nonprofit creates a new heart monitoring machine employing wireless technology.
April 20, 2011

An inexpensive portable device could make it easy to monitor fetal health in remote locations, and it might also provide an alternative to more expensive machines currently used in doctors’ offices in the developed world.

Maternal monitoring: A device designed by the West Wireless Health Institute measures fetal heart rate via an ultrasound monitor (lower belt) and maternal contractions via another sensor (higher belt), and then transmits the data via Bluetooth to a tablet (left).

The device, a cardiotocography machine dubbed Sense4Baby, was designed by engineers at the nonprofit West Wireless Health Institute, a medical research organization whose mission is to use wireless technology to reduce the cost of health care.

“We designed Sense4Baby from the ground up to be low-cost,” says Joe Smith, West Wireless’s chief medical officer. “It takes every advantage of consumer-scale microelectronics and ubiquitous low-cost communication infrastructure.” The institute is now planning field tests of the device in Mexico and is in talks to organize tests at major health-care systems in the United States. The device has not yet been approved by the U.S. Food and Drug Administration.

Cardiotocography machines are currently used by obstetricians, typically during the third trimester and in high-risk pregnancies, to measure fetal heart rate and uterine contractions as an indicator of fetal distress. The heart rate of a healthy fetus drops during a contraction and then rapidly comes back to normal. “If the doctor sees a lack of change or early or late changes in heart rate, it could be a sign of trouble,” says Steven Garverick, an engineer at West Wireless who has been leading the project.

Sense4Baby uses the same basic sensors as existing devices: Doppler ultrasound to measure fetal heart rate and a pressure sensor called a tocodynamometer (or toco) to measure the force of the contraction via the tension of the maternal abdominal wall. But it eliminates the large bedside machine used to process these measurements in standard cardiotocography, replacing it with a Bluetooth transmitter and a smart phone or tablet running custom software.

“We took a fresh look at problem, designing a tiny device that could combine traditional measurements with a Bluetooth transmitter so that data can be sent wirelessly to a cell phone or computer,” says Garverick. “The data is transmitted via a cell phone to the Internet, where it can be analyzed in a semi-automated way and used to make treatment and monitoring decisions.”

The initial prototype, which incorporated an off-the-shelf handheld ultrasound device, performed just as well as a standard cardiotocography machine, and was able to detect a range of 50 to 240 heartbeats per minute. The team is now working on a second-generation device whose novel circuit design should help further reduce the size and cost. It also has additional features, such as the ability to track multiple babies at once. Garverick says it’s difficult to estimate the cost of the new device in production, but he predicts it will be in line with the cost—about $100—of consumer ultrasound monitors that perform much more limited functions.

Sense4Baby is part of a larger trend toward using consumer electronics and wireless technology to develop more portable and easier-to-use medical devices, such as cell-phone-based ultrasound. “The baby monitor is a great example of taking a device and making it more efficient,” says David Zar, a computer scientist at Washington University in St. Louis and chief technology officer at Mobisante, a startup that has developed one such system. “There is no new medical technology being developed, but rather, they are taking existing technology and packaging it in a way that becomes less expensive and more convenient for everyone.” Zar is not involved with West Wireless.

For the first field tests of the device, in Mexico, researchers hope to use it to monitor women in rural areas who are unable to travel regularly to a clinic. Unicef estimates that 80 percent of maternal deaths could be prevented with access to essential obstetric and other health-care services, including monitoring technology. “If we can keep the cost down, hopefully it can be used in all pregnancies and done at home, so the mother doesn’t have to make three trips to the hospital,” says Garverick. He adds that there is significant interest in the United States as well. “We have had interest from major health institutes to employ these in studies,” he says.

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