Estimating electrical current from uterus muscle may provide clues to preterm birth

Non-invasive technique could provide a useful tool for clinicians

The SARA device used to non-invasively take MMG measurements of uterine activities.

Preterm birth, or birth before 37 weeks, affects one in 10 babies born nationally and globally, leading to a variety of complications and even death. While the causes are not well understood, researchers at Washington University in St. Louis and collaborating institutions are the first working to estimate electrical source currents in the uterus during real contractions to determine their potential impact on labor.

Building on earlier work, Arye Nehorai, the Eugene & Martha Lohman Professor of Electrical Engineering in the School of Engineering & Applied Science at WashU, and collaborators developed a method to estimate electrical current in the uterus during contractions from magnetomyography, a noninvasive technique that maps muscle activity by recording the abdominal magnetic fields that electrical currents in muscles produce. The results, published in PLoS One Aug. 23, could have clinical applications in better understanding pre- and post-term birth and dysfunctional labor.

The team collected data from two pregnant women at the University of Arkansas for Medical Sciences using a device that allows the women to lean forward into a concave space. Within the SARA device are 151 primary magnetic sensors placed 3 centimeters apart that measure electrophysiological signals from the patient's abdomen. They divided the uterus into 25 contiguous regions.

Through the studies, they were able to estimate the underlying source currents in the smooth muscle of the uterus and predicted the pressure within the uterus, which is currently used to measure contractions.

"This is only the beginning," Nehorai said. "Our work is potentially important as a starting point for helping to characterize underlying activities of uterine contractions during pregnancy and future diagnosis of contractile dysfunction."

The team's next steps are to use the estimated currents in the uterus to predict labor and early labor. They plan to develop efficient algorithms that would be made available to clinicians through software.

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