The researchers say their ultimate goal is to help obstetricians and gynecologists use measurements of electrical activity in the uterus to help predict whether a woman will have preterm or term labor.
Understanding the nature and causes of contractions in pregnancy helps shed light on the processes of normal and preterm birth - defined as that which occurs before 37 weeks of gestation.
Techniques such as electromyography (EMG) and magnetomyography (MMG) have been developed to study and measure uterine contractions. However, no widely accepted method using these techniques to predict preterm labor is available.
In a paper published in the journal PLOS One, the researchers - including members from Washington University in St. Louis (WUSTL), MO - describe how they developed the first 3-D multiscale mathematical model of the electrophysiology of a pregnant woman's uterine contractions.
The model represents contractions at the cell, tissue, and organ level. A key feature of a contraction is the fiber architecture of the myometrium - the middle layer of tissue in the wall of the uterus that is largely responsible for contractions.
The researchers note that another important feature of a contraction is the location of what they call the "pacemaker" - the cell that starts the electrical activity. Senior author Arye Nehorai, a professor in electrical engineering at WUSTL, explains:
"We know that the cell starts the electrical activity, but nothing is known about the positions or numbers or how they interact in different places in the uterus. In addition, we don't yet know the directions of the fibers in the myometrium, which is important because the electricity propagates along the muscle fibers, and that direction varies among women."
In their paper, the researchers describe how they applied sensors to the abdomens of 25 pregnant women and produced a 3-D mathematical model that precisely replicated the electrical activity in the uterus during a contraction.
'Realistic, multiscale forward model of uterine contractions'
The sensors were attached to a special instrument comprising 151 magnetometers that measured the strength of the magnetic field generated by the electrical activity in the women's abdomens during a contraction. The researchers used these measurements to create the model.
The team now plans to study preterm and term labors and take measurements with the magnetometer instrument to estimate the electrical activity and the position, number, and distribution of the electrical sources in the uterus.
This way, they may be able to pinpoint which patterns and measurements can predict which labors are going to be preterm.
"Creating a realistic, multiscale forward model of uterine contractions will allow us to better interpret the data of magnetomyography measurements and, therefore, shed light on the prediction of preterm labor.
Our ultimate goal is to share this with obstetricians and gynecologists so they can take measurements and make a prediction of whether a woman will have preterm or term labor."
Prof. Arye Nehorai
The earlier babies are born, the higher the risk they will have serious health problems or die. As well as these risks, preterm births cause huge financial burdens to families and society.
According to the World Health Organization, an estimated 15 million babies are born preterm worldwide, and the number is rising. Across 184 countries, the rate of preterm birth ranges from 5-18 percent of babies born.
Preterm birth complications are the leading cause of death in children under the age of 5 worldwide and were responsible for nearly 1 million deaths in 2013.