Placental abruption occurs when the placenta separates from the uterus before birth, which can deprive the baby of oxygen and nutrients. It can cause bleeding, pain, and in severe cases can threaten the lives of the mother and baby. Risk factors include prior abruption, high blood pressure, smoking, older maternal age, and abdominal trauma. Treatment depends on gestational age but may involve monitoring, medications to aid lung development, or emergency delivery by c-section.