What are the most common conditions and concerns?

Conditions that can affect the placenta include:

• Placental abruption. This is when the placenta partly or completely peels away from the inner wall of the uterus before delivery. With placental abruption, the developing baby might not get enough oxygen and nutrients. The pregnant person might have back or stomach pain and bleeding from the vagina. Placental abruption can lead to an emergency in which a baby needs to be delivered early.

• Placenta previa. This condition happens when the placenta partly or totally covers the cervix. Placenta previa is more common early in pregnancy. It might get better on its own as the uterus grows.

  Placenta previa can cause serious vaginal bleeding during pregnancy or delivery. Treatment depends on various factors. They include the amount of bleeding, whether bleeding stops, how far along the pregnancy is and the placenta's position. If placenta previa continues late into the pregnancy, a healthcare professional likely will recommend a C-section.

• Placenta accreta. Most often, the placenta separates from the wall of the uterus after childbirth. With placenta accreta, part or all of the placenta stays firmly attached to the uterus. This condition happens when the blood vessels and other parts of the placenta grow into the uterine wall. This can cause serious blood loss during delivery.

  Sometimes, the placenta invades well into the muscles of the uterus or grows through the uterine wall. If this happens, a healthcare professional likely will recommend a C-section followed by surgery to remove the uterus. This is called a C-hysterectomy.

• Retained placenta. With a vaginal birth, the placenta most often is delivered soon after the baby. But if the placenta isn't delivered within 30 minutes after childbirth, it's known as a retained placenta. A retained placenta might happen because the placenta becomes trapped behind a partially closed cervix. Or it might happen because the placenta is still attached to the uterine wall.

  Without treatment, a retained placenta can cause a serious infection or life-threatening blood loss. Treatment may include medicine to help deliver the placenta or a procedure to remove the placenta.