Placental disorders or abnormalities occur when, during pregnancy, the placenta develops in the uterus in an unusual location or invades the wall of the uterus.

Overview and Symptoms

Placental disorders are rare and include:

  • Placenta previa: occurs when the placenta covers some or all of the cervix. It’s usually detected on ultrasound. A common symptom is vaginal bleeding, especially during the third trimester. Beginning labor can tear the placenta covering the cervix, causing bleeding.
  • Placenta accreta: refers to when the placenta grows too firmly or too deeply into the lining of the uterus, making it unable to separate from the uterine wall upon delivery (as a normal placenta does), potentially leading to hemorrhage and other complications.
  • Placenta increta: occurs when the placenta grows at least halfway through the wall of the uterus.
  • Placenta percreta: occurs when the placenta grows completely through the wall of the uterus; in some cases, placental tissue will continue to grow into nearby pelvic organs, including the bladder or colon.


Though placental disorders are rare, they carry risks to pregnancy that require complex care, which is best obtained from providers with expertise in these abnormalities and at hospitals, such as New England Center for Placental Disorders at BIDMC, that have access to an array of technological capabilities.

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The Department of Obstetrics and Gynecology at BIDMC provides outstanding care for all women throughout their lives, in a friendly, comfortable and safe environment.

Obstetrics and Gynecology