By: 15 August 2014
Electrical switch during labour could be faulty in overweight women

Overweight women have a higher likelihood of irregular contractions and are more likely to require a caesarean section than other women, according to the findings of a studypublished in Nature Communications.

The groundbreaking research from Monash University, the Royal Women’s Hospital and the Hunter Medical Research Institute, shows that a potassium ion channel called hERG in the uterus acts as a powerful electrical brake during pregnancy to suppress contractions and prevent premature labour. At the onset of labour, a protein switch turns hERG off, thereby removing the brake and ensuring that labour can take place.

The team, led by Professor Helena Parkington from the School of Biomedical Sciences at Monash University, found that in overweight women the switch doesn’t work, failing to turn hERG off.

“We’ve known for years that women who are overweight are much more likely to experience complications during pregnancy and labour – but we didn’t know why,” said Parkington. “Pinpointing the mechanism is a major breakthrough; not only does it ensure a smooth pregnancy, but knowing when contractions kick in at more or less the right time, is crucial to our understanding of the labour process.”

Over 50% of Australian women are overweight or obese, according to figures from the Royal Women’s Hospital, including 35% of women aged 25–35. Testing the electrical signals in small amounts of uterine tissue taken from women who had an elective caesarean before labour started and women who needed an emergency caesarean during their labour, showed striking differences between overweight women and those of a healthy weight, proving that hERG was dysregulated in overweight women.

“Now we know what is responsible for malfunctioning labour in overweight women, we can look to develop treatments to correct the ‘faulty’ switch and ensure both safer pregnancies and labour for women and their babies,” said Parkington.

The next phase of research will look at developing a safe, effective and specific treatment to allow labour to start
and progress.

Parkington, K.C., Stevenson, J. & Tonta, M.A. (2014) Diminished hERG K channel activity facilitates strong human labour contractions but is dysregulated in obese women. Nature Communications (doi: 10.1038/ncomms5108)