An abruptio placentae (i.e. placental abruption) is the separation of the normally located placenta before the baby is born and after the 20th week of the pregnancy.

Placental abruption, including any amount of placental separation prior to delivery, occurs in about 1 out of 150 deliveries. The severe form, which results in fetal death, occurs only in about 1 out of 500 to 750 deliveries.

The exact cause of a placental abruption is often difficult to determine. Direct causes are rare, but include:

• Abnormally short umbilical cord
• Injury to the belly area (abdomen) from a fall or automobile accident
• Sudden loss in uterine volume (can occur with rapid loss of amniotic fluid or the delivery of a first twin)

Risk factors for an abruptio placentae include:

• Advanced maternal age
• Cigarette smoking
• Cocaine use
• Diabetes
• Drinking more than 14 alcoholic drinks per week during pregnancy
• High blood pressure during pregnancy - About half of placental abruptions that lead to the baby's death are linked to high blood pressure
• History of placenta abruptio
• Increased uterine distention (as may occur with multiple pregnancies or abnormally large volume of amniotic fluid)
• Large number of prior deliveries