Gestational age approximately 20 to 23 weeks. Perform an emergency hysterotomy to enable successful resuscitation of the妊娠年龄为20～23周的孕妇施行急诊剖宫产手术能对母亲成功施行复苏，但不可能挽救婴儿的生命。
Gestational age approximately _24 to 25 weeks. Perform an emergency hysterotomy to save the life of both the mother and 妊娠年龄大于等于24～25周的孕妇施行急诊剖宫产能同时挽救母亲和胎儿的生命。