Understanding the Meaning of Placenta Previa and Miscarriage Risk

Healthy pregnancies are still possible with placenta previa

Pregnant Hispanic woman touching her belly
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It can be scary to get a diagnosis of placenta previa, a condition where the placenta 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 during the first 10 to 20 weeks of pregnancy, but most of these early cases, around 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.

What causes placenta previa is unknown, but if you smoke cigarettes, use cocaine, are above the age of 35, have been pregnant before, are carrying more than one baby, and have had surgery on your uterus (including c-section or D&C), your risk of placenta previa is higher. If you had placenta previa during a prior pregnancy, you are also more likely to experience it again in a future pregnancy. 

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 placenta previa.

Diagnosing Placenta Previa

Placenta previa can usually be detected during an ultrasound, through routine testing most practitioners perform around the 20th week of pregnancy. If you have not had ultrasounds during your pregnancy, the condition may be discovered when she starts bleeding. 

Outcomes for babies from placenta previa pregnancies have been improving thanks to prenatal medical care.

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

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. 

Navigating Pregnancy With Placenta Previa

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 restrict travel if you are bleeding. Women with placenta previa are sometimes hospitalized in the third trimester, in case they spontaneously go into labor, which could also cause severe bleeding. 

Early delivery by c-section will most likely be recommended if your 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.

 

Sources

  • 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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