Birth ball for pregnant women in labour research protocol: a multi-centre randomised controlled trial.

Background: Birth ball is one of the non-pharmacologic pain relief methods to help mothers cope with the labouring process. A randomised controlled trial (RCT) is conducted to evaluate the effectiveness, safety and harm of birth ball use by pregnant women in labour compared to treatment as usual group.

Methods: A prospective multi-centre randomised controlled trial (RCT) will be conducted in Obstetrics and Gynaecological units of five public hospitals in Hong Kong, China. Data will be collected from March 2016 onward for 2 years. The target population is Chinese women with an uncomplicated singleton pregnancy at gestational age of 37 to 42 weeks. Participants are randomised based on parity (nulliparous and multiparous) and type of labour onset (spontaneous and induced). Women in the intervention group are actively offered and taught how to use a birth ball; those in the control group receive the usual midwifery care. The target sample size is 512. The primary outcome measures are maternal pain intensity, satisfaction with pain relief, sense of control in labour, assisted delivery and satisfaction with childbirth experience. Labour pain relief is measured by visual analogue scale (VAS). Other outcomes will be measured through four different validated questionnaires. To control for potential cluster effects, a linear mixed model will be used. An intention-to-treat analysis is adopted and performed by researchers unknown to subjects' group allocation.

Discussion: Results will provide rigorous scientific evidence for policy development and practice. We are using stratified randomisation according to potential confounders of parity and type of labour onset to give four possible combinations. If the results are favourable, it will facilitate systematic implementation to promote birth ball use for women in labour.

Trial Registration: Chinese Clinical Trial Register (ChiCTR), Registration number: ChiCTR-IIC-16008275 , Date of registration 12 April 2016 (retrospectively registered), Date of enrolment of the first participant to the trial 1 March 2016.