What is the definition of placenta previa?

The correct definition of placenta previa is the abnormal implantation of the placenta in the lower portion of the uterus. In this condition, the placenta is positioned either partially or wholly over the cervix, which can lead to complications during pregnancy and delivery. As the pregnancy progresses and the uterus expands, the presence of the placenta in this location can obstruct the birth canal, resulting in significant bleeding and potential risks for both the mother and the baby during labor.

Other definitions listed do not accurately describe placenta previa. The second option refers to a condition known as placental abruption, which involves the premature separation of the placenta from the uterine wall, while the third and fourth options describe normal placental positioning, which is generally in the upper part of the uterus away from the cervix. Understanding the correct definition is crucial for managing care and making informed decisions during pregnancy.