The women in both groups were similar in age, marital status, and body mass index (BMI).They also had similar rates of epidural anesthesia, induction of labor, episiotomies, and shoulder dystocias.

• 这两组母亲在年纪、婚姻状况、身体质量指数（BMI）相似，且硬膜外麻醉、催产、会阴切开与肩部难产发生率上也是相似的。