Sample size and power
RECRUITMENT
The sample size calculation was based on two independent means derived from the pilot study. The trial was designed to demonstrate minimum detectable differences in the duration of labour between two groups as one hour and anticipate an attrition rate of 10% since outcomes were measured until 40 weeks of gestation. This required a total sample size of 140 primigravid women in each arm of the trial for 80% power at a significance level of p<.05. Recruitment continued until at least 140 women had been enrolled, and from those randomized to the intervention group, 138 completed the study and two were excluded due to elective Lower Segment Caesarean Section (LSCS) or non-reactive Non Stress Test (NST). A low dropout rate (<7%) was observed for the overall study population.