Causes

Amniotic fluid embolism occurs when amniotic fluid or fetal material enters the mother's bloodstream. A likely cause is a breakdown in the placental barrier, such as from trauma.

When this breakdown happens, the immune system responds by releasing products that cause an inflammatory reaction, which activates abnormal clotting in the mother's lungs and blood vessels. This can result in a serious blood-clotting disorder known as disseminated intravascular coagulation.

However, amniotic fluid embolisms are rare — and it's likely that some amniotic fluid commonly enters the mother's bloodstream during delivery without causing problems. It's not clear why in some mothers this leads to amniotic fluid embolism.