Labour and birth outcomes.

aValues adjusted for maternal SES, BMI, and indication for previous caesarean birth.RCT, randomised controlled trial.经产妇社会经济地位（socioeconomic status, SES）、体质量指数（Body Mass Index, BMI）及既往剖宫产指征校正后的a值。随机对照试验（randomised controlled trial, RCT）。