宫颈机能不全之先天性宫颈内口松弛为每次妊娠都有会发生早产或流产;而后天性子宫内口松弛症则表现为发生早产或流产的时间越来越早，或刚开始可正常妊娠分娩，而后因某种原因出现早产或流产。

　　Congenital cervical dilatation of cervix causes premature delivery or miscarriage in every pregnancy. And then the nature of uterine mouth laxity is manifested in the occurrence of premature birth or abortion time earlier and earlier, or the beginning of normal pregnancy and childbirth, and then for some reason there is premature birth or abortion.