Placenta Previa and Miscarriage Risk

Preterm Birth Is the Biggest Concern with This Pregnancy Condition

pregnant woman with doctor
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It can be scary to get a diagnosis of placenta previa, the medical term for a placenta that sits low in the uterus, covering part or all of the cervix. Placenta previa is not associated with miscarriage or pregnancy loss, but it can cause severe bleeding and increase the risk of preterm birth and infant death. 

According to the March of Dimes, placenta previa occurs in 1 in 200 pregnancies. It's much more common in the first 10 to 20 weeks of pregnancy, but most of these early cases (90 percent) resolve themselves.

 Depending on where you are in your pregnancy, there's a good chance that your condition will correct itself before you give birth.

When the condition does not self-correct during pregnancy, a c-section may be necessary to prevent dangerous complications in later pregnancy.

The cause of placenta previa is not known, but risk is highest in women who:

  • smoke cigarettes
  • use cocaine
  • are 35 or older
  • have been pregnant before
  • are carrying more than one baby
  • have had surgery on the uterus, including c-section or D&C 

Women who have had the condition in prior pregnancies are more likely to experience recurrence. 

What Are the Symptoms of Placenta Previa?

Bleeding after 20 weeks gestation is the most common symptom of placenta previa. Most women have painless bleeding, while a smaller number have either bleeding with uterine contractions or no bleeding.

Any bleeding in the second or third trimester of pregnancy should be reported to a physician without delay, whether or not you have been told you have placenta previa.

How Is Placenta Previa Diagnosed?

Placenta previa is usually detected during ultrasound, often during the routine testing most practitioners perform around the 20th week of pregnancy.

Or, if a woman has not had ultrasounds during her pregnancy, it may be discovered when she starts bleeding. 

How Dangerous Is It?

Outcomes for babies with placental previa pregnancies have been improving thanks to better medical care that starts before the baby is even born.

Placenta previa does not cause miscarriage or stillbirth. However, in 10.7 out of 1,000 cases, placental previa does lead to an infant's death during the first month of life. This is usually related to preterm birth. Although preterm birth is more common in placenta previa, it's important to know that most babies are born at term. 

Fortunately, in the U.S., placenta previa is rarely fatal for the mother. If you've had severe heavy bleeding, you may need a blood transfusion. 

What to Expect After a Diagnosis

If you've been diagnosed with placenta previa, you may be advised to avoid intercourse or strenuous exercise. Your doctor may also advise bed rest and travel restriction if you have experienced bleeding. Women with placenta previa are sometimes hospitalized in the third trimester, in case they spontaneously go into labor, which could cause severe bleeding. 

Early delivery by c-section will most likely be recommended if the placenta previa is still present in the third trimester. Your doctor may give you corticosteroids to boost your baby's lung maturity. 

It's scary to be told that there is anything wrong with your pregnancy that might threaten your baby, but remember that most women with placenta previa are able to carry their babies to term without serious complications.



Clinical features, diagnosis, and course of placenta previa. UpToDate. August 21, 2015.

Placenta previa. March of Dimes. January 2012.

ACOG Education Pamphlet AP038. American College of Obstetricians and Gynecologists. Accessed: Aug 2, 2009. 

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