A new study shows that a potassium ion channel called hERG in the uterus is responsible for difficult labor among overweight pregnant women.
Acting as a powerful electrical brake, hERG works during pregnancy to suppress contractions and prevent premature labor. However, at the onset of labor a protein acts as a switch to turn hERG off, removing the brake and ensuring that labor can take place.
Specifically, testing the electrical signals in small amounts of uterine tissue taken from women who had an elective caesarean before labor started and women who needed an emergency caesarean during their labor, proved that hERG was dysregulated in overweight women.
Pregnant women who are overweight often continue pregnant past their due date or progress slowly when labor begins.
Overweight women have higher rates of medical interventions around labor and birth, including higher rates of induction for prolonged pregnancy, and higher rates of Caesarean section as a result of failure to progress in labor.
Lead researcher Professor Helena Parkington of Monash University says this “switch” needs to be turned off to allow labor contractions to occur, but remains turned on in overweight women.
“The reason it stays on is that the ‘molecular hand’ that should turn the switch off fails to appear in sufficient quantities in the uterine muscle of overweight women when labor should be occurring. These women also respond poorly to our current methods of induction,” says Parkington.
Professor Shaun Brennecke of the University of Melbourne and Royal Women’s Hospital says the finding significantly advances understanding of how labor progresses, with implications for all women who have complicated labors.
“The clinical significance of this discovery is that, having identified the problem responsible for dysfunctional labor in overweight women, we are now able to look at developing a safe, effective, and specific treatment to correct the problem.”
“For example, a drug to turn off the switch to allow normal labor to start and progress,” he says.
The study appears in Nature Communications.