Definition of Placenta abruptio:

Placenta abruptio is the separation of the placenta (the organ that nourishes the fetus) from its attachment to the uterus wall before the baby is delivered.

Causes, incidence, and risk factors:

The exact cause of a placental abruption may be hard to determine.

Direct causes are rare, but include:

• Injury to the belly area (abdomen) from a fall, hit to the abdomen, or automobile accident
• Sudden loss of uterine volume (can occur with rapid loss of amniotic fluid or after a first twin is delivered)

Risk factors include:

• Blood clotting disorders (thrombophilias)
• 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 (may occur with multiple pregnancies or very large volume of amniotic fluid)
• Large number of past deliveries
• Older mother
• Premature rupture of membranes (the bag of water breaks before 37 weeks into the pregnancy)
• Uterine fibroids

Placental abruption, which includes any amount of placental separation before delivery, occurs in about 1 out of 150 deliveries. The severe form, which can cause the baby to die, occurs only in about 1 out of 800 to 1,600 deliveries.