University of Otago researchers have made a discovery which is ``exciting scientifically'' and eventually could help prevent preterm birth in at-risk pregnant women.
The researchers have discovered a new trigger that stimulates the release of oxytocin from the brain in pregnancy-the powerful hormone responsible for contracting the uterus during birth.
The protein kisspeptin is well known to be important for fertility and puberty.
But the Otago team, led by Prof Colin Brown of the Otago physiology department, and the Brain Health Research Centre, has now found kisspeptin also causes oxytocin cells in the brain to get ``excited'', triggering rhythmic contractions of the uterus.
The study found a specific group of brain cells that control oxytocin cells start to make kisspeptin in late pregnancy, and that giving kisspeptin only excites oxytocin cells in late-pregnant rats, not in virgin rats or those in earlier pregnancy.
The researchers believe kisspeptin's early release in humans might increase the risk of preterm births. These are births occurring more than three weeks before the baby is due.
Prof Brown says the discovery, just published in the Journal of Physiology, could potentially enable new therapies to be developed.
Pregnant women lacking oxytocin were likely to have a delayed birth, but this could be managed by giving a dose of oxytocin.
But if oxytocin was secreted too early, preterm delivery could result.
Preterm birth was a ``big problem'' and in most cases, ``doctors don't know why it happens,'' he said.
In New Zealand about 7% to 8% of women deliver their babies preterm, and alarmingly this percentage-consistent across the developed world- was not decreasing.
Blocking the effects of kisspeptin in late pregnancy could provide a ``more specific therapy'' to manage pregnancies at risk of preterm delivery than current methods.
The significance of these findings, funded by a $1 million Health Research Council (HRC) project grant, has led to further funding as part of the $5 million HRC-funded programme ``Healthier pregnancy, healthy babies'', led by Prof David Grattan of the Otago anatomy department, and the Centre for Neuroendocrinology, of which Prof Brown is also a member.
HRC chief executive Prof Kath McPherson said preterm delivery is the most common cause of death in newborn babies in this country, and preterm birth survivors were more likely to suffer chronic illness as adults.