Pregnancy researchers unlock key to triggering labour

Jun 18 2014

Professor Roger Smith

Pioneering research by the University of Newcastle’s Mothers and Babies Research Centre has led to the discovery of an electrical ‘switch’ in the uterine muscle that fails to engage in pregnant women who are overweight, potentially causing labour complications.

As published today in the prestigious international journal Nature Communications, the findings provide significant insight into why overweight women tend to have long and difficult labours, often resulting in higher rates of Caesarean delivery.

Senior author of the new paper, Professor Roger Smith, said his HMRI-based laboratory staff had been profiling the many genetic changes that occur as a woman goes into labour, when one gene particularly sparked their interest.

It coded for what is known as a potassium channel.

“We knew that potassium channels were involved in the onset of labour but there are hundreds of them in the human genome and no one knew which was the key to controlling contractions,” Professor Smith explained.

“By blocking this particular channel, known as the hERG channel, we found it led to extremely powerful contractions – we knew we’d found the so-called electrical switch.”

Working in collaboration with researchers from Melbourne, the team has subsequently shown that the hERG channel fails to function correctly in overweight mothers.

“The electricity must be switched off to allow labour contractions to occur effectively, but the switch stays turned on in overweight women,” lead author Professor Helena Parkington, from the Monash School of Biomedical Sciences, said.

“The ‘molecular hand’ that should turn the switch off fails to appear in sufficient quantities in the uterine muscle of overweight women. These women also respond poorly to our current methods of induction.

“It’s the first time that the switch and the ‘molecular hand’ controlling it have been identified in uterine muscle. We are now able to look at developing a safe, effective and specific treatment to correct the problem.”

Professor Smith said the findings might also give clues to treating women in pre-term labour, where early inactivation of this channel potentially occurs.
“The best way to have a long and healthy life is to be born at the right weight and at the right time,” Professor Smith said. “So the best way mums can help ensure this is to stop smoking and maintain a healthy body weight before pregnancy occurs.”

* Professor Roger Smith is the Director of the Mothers and Babies Research Centre at the University of Newcastle and head of the HMRI Pregnancy and Reproduction program. HMRI is a partnership between the University of Newcastle, Hunter New England Health and the community.