Soft, Flexible Sensors Can Wirelessly Monitor Pregnant Women and Their Fetuses

By Linda Carroll

May 11, 2021

(Reuters Health) - An interdisciplinary team of scientists has developed a wireless network of three soft, flexible sensors that can measure the vital signs of a laboring mother and her fetus, as well as provide data on contractions, according to a new report.

The monitoring system was run through its paces in a study with 91 U.S. women and 485 women in Zambia, and the results published in the Proceedings of the National Academy of Sciences.

"This is, to my knowledge, the first fully comprehensive system for wirelessly monitoring pregnant women," said coauthor John Rogers, the Simpson-Querrey Professor of Biomedical Engineering at Northwestern University in Chicago. "It's scalable, so that it can be deployed not only in advanced high-resource hospital settings, but also in remote clinics around the world."

What makes the system so portable is the fact that the sensor data can be sent directly to a smart phone, and thus it can provide remote monitoring for mothers who live in remote, rural areas, and for those who want to minimize doctor visits during a pandemic, Rogers said.

New and novel features include sensors that are "soft like Band-Aids" and "ICU-level monitoring from devices that are wirelessly synchronized," Rogers said.

The system currently does not have Food and Drug Administration approval. Rogers hopes that will happen in "the next couple of years."

The new system consists of three sensors: one, which adheres to the mother's abdomen, contains an accelerometer and monitors both the baby's heartbeat and the mother's contractions; a second, which adheres to the mother's chest, monitors her heart, respiratory rate and core temperature; a third, which wraps around the mother's finger, monitors her oxygen levels and peripheral body temperature.

Maternal blood pressure is derived from the pulse wave velocity, as determined from the time-synchronized outputs of the chest and the limb sensors. "Some of the biggest complications of pregnancy are not silent," said senior study author Dr. Shuai Xu, an assistant professor of dermatology at Northwestern University Feinberg School of Medicine, a Northwestern Medicine dermatologist and medical director of the Querrey Simpson Institute for Bioelectronics (QSIB).

"Their physiological parameters as measured by our systems capture this," Dr. Xu said in an email. "This includes pre-eclampsia, post-operative infections, chorioamnionitis, and hemorrhage."

To test the new technology, the researchers equipped 576 pregnant women - including 91 recruited from Prentice Women's Hospital in Chicago and 485 from Lusaka, Zambia - with the wireless sensor system alongside traditional monitoring systems during labor.

For the U.S. patients, the sensors were placed on the participant for a period of time that did not interfere with clinical care, ranging from 25 minutes to several hours during both nonstress testing (n = 59) and active labor (n =32).

The Zambian patients were participants in the Limiting Adverse Birth Outcomes in Resource-Limited Settings (LABOR) study), which is documenting labor, delivery, and the early postpartum period in 15,000 mother-newborn pairs via detailed physiological data generated by the network of sensors along with blood and urine samples and clinical data. In Zambia, the sensors were placed on the women during their entire labor, ranging from one hour to more than 24 hours. All the Zambian women were actively in labor with imminent delivery.

SOURCE: PNAS, online May 10, 2021.