If the placenta peels away from the inner wall of the uterus before delivery — either partially or completely — it's known as placental abruption (abruptio placentae).
Placental abruption is an uncommon and serious complication of pregnancy.It occurs in 1% of pregnancies world wide with a fetal mortality rate of 20-40% depending on the degree of separation. Placental abruption is also a significant contributor to maternal mortality.
Trauma, hypertension, or coagulopathy contributes to the avulsion of the anchoring placental villi from the expanding lower uterine segment, which in turn, leads to bleeding into the decidua basalis. This can push the placenta away from the uterus and cause further bleeding.Women may present with vaginal bleeding, abdominal or back pain, abnormal or premature contractions, fetal distress or death.