High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial

Background:

Approximately 1/3 of first-time mothers (nulliparous women) undergoing induction of labour deliver by cesarean. Cesarean delivery can have negative consequences to the initial and subsequent pregnancies. Women who have a cesarean in their first pregnancy are more likely to have a cesarean in their following pregnancies and this group is the largest contributor to the overall cesarean delivery rate. Therefore, targeting interventions that prevent cesareans in nulliparous women undergoing induction of labour will have a substantial impact on the overall cesarean delivery rate.

Adequate ripening or preparing the cervix before induction has been found to decrease the risk of cesarean. This can be done by a variety of methods, such as prostaglandins (a chemical messenger) or a Foley filled to a moderate volume of fluid. These methods have been found to be equal regarding the risk of cesarean delivery. However, a meta-analysis by our team discovered a trend towards a decreased risk of cesarean when cervical ripening is undertaken with Foleys filled to a high volume of fluid (80cc) compared to those filled to a low volume (30cc).Most Canadian Obstetricians use prostaglandins for cervical ripening. To assess if 80cc Foleys result in a lower risk of cesarean, they need to be compared to the Canadian standard of prostaglandins. Therefore a randomized controlled trial is required.

The Greater-Toronto-Area Obstetric (GTA-OB) Network is a group of hospitals committed to facilitating research and will be the setting for the planned large scale trial. The large scale trial will aim to demonstrate a difference in the rate of cesarean from 38% to 31%, which will require the enrollment of 1442 women. It has been estimated that there are 5,437 women who will meet entry criteria in the GTA-OB network each year, if ½ are approached, 20% will need to consent to complete the trial in 3 years. Therefore, this pilot study will determine if this recruitment rate is potentially achievable and will inform design strategies to ensure its success.

The discovery of a simple, non- pharmacological, cost effective manner of cervical ripening that decreases the risk of cesarean would change clinical practice and significantly improve safety for the 33,000 Canadian women and their babies who undergo cervical ripening each year. This pilot trial is a crucial step towards this discovery.