17.3.4  Cervical incompetence

Without uterine contraction, the cervix may dilate spontaneously early in gestation and this can be the cause for an abortion (miscarriage). The cervix may dilate even in late pregnancy before the onset of labour. As the cervix continues dilating, it will allow part of the fetal membranes to pass through it. As a result, the membranes can rupture easily and leak amniotic fluid.

17.3.3  Multiple pregnancy and excess amniotic fluid

17.3.5  Trauma to the abdomen