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Definition

By Mayo Clinic staff

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Illustration showing placement of normal placenta and placenta previa Placenta previa

Placenta previa is an uncommon pregnancy complication that can cause excessive bleeding before or during delivery.

Soon after conception, the placenta begins to form. This oval, flat organ provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. It attaches to the wall of your uterus, and your baby's umbilical cord arises from it, forming a vital connection between you and your baby.

Placenta previa occurs when the placenta attaches to the lower part of your uterine wall, partially or totally covering your cervix. When the cervix starts to open in preparation for labor, the placenta is detached, which can trigger severe vaginal bleeding. Thankfully, placenta previa is nearly always detected before a woman or her baby is in significant danger.

References
  1. Lockwood CJ, et al. Clinical manifestations and diagnosis of placenta previa. http://www.uptodate.com/hom. Accessed April 17, 2009.
  2. Sakornbut E, et al. Late pregnancy bleeding. American Family Physician. 2007;75:1199.
  3. Zeltzer JS. Vaginal bleeding in late pregnancy. In: Rakel RE, et al. Conn's Current Therapy 2008. 60th ed. Philadelphia, Pa.: Saunders Elsevier; 2008. http://www.mdconsult.com/das/book/body/132444171-3/831220627/1621/508.html#4-u1.0-B978-1-4160-4435-2..50256-9_4080. Accessed April 17, 2009.
  4. Lockwood CJ, et al. Management of placenta previa. http://www.uptodate.com/hom. Accessed April 17, 2009.

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June 2, 2009

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