Objective To investigate the efficacy and safety of bionic air-bag midwifery skill.Methods Totally 2410 primiparas were randomly divided into air-bag group and control group.Women in air-bag group ware given the same obstetrical treatments as that in the control group except bionic air-bag midwifery skill was used twice when the cervix was dilated 2~4 cm during labor.Results The time of first stage,second stage and total delivery process in the air-bag group were shorter than those in control group(P<0.01,P...