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What is Placenta Previa?


Placenta previa refers to a condition where the placenta is attached very low down on the uterine wall and perhaps right over the cervix.

Placenta previa occurs in around 2% of pregnancies and you will normally find out if you have this condition at your 20 week scan.

What causes placenta previa?

The placenta grows wherever the embryo has actually implanted itself within the uterus. If the embryo happens to implant in the lower part of the uterus, the placenta might grow low down on the uterine wall or even over the cervix — causing placenta previa.

Early placenta previa often resolves itself if the placenta doesn't actually cover the cervix, with the expansion of the uterus eventually pulling it up and further away from the cervix. Although, if the placenta is covering the cervix at any time, it is unlikely to resolve as the pregnancy progresses. 

Placenta previa can happen within any pregnancy but there are a couple of particular risk factors for the condition, these being:

  • A previous Cesarean section

  • Previous surgery undertaken to remove uterine fibroids

Placenta previa is also more common with women who:

  • Have had placenta previa with a previous pregnancy
  • Have delivered at least one baby previously
  • Are carrying a multiple pregnancy
  • Are aged 35 or older
  • Smoke

What are the symptoms of placenta previa?

The main symptom of Placenta Previa is light to heavy vaginal bleeding, which will generally occur within the second half of pregnancy. Contractions may also accompany this bleeding. Bear in mind though that there are many causes of bleeding of spotting in pregnancy and placenta previa may well not be the cause. If you are unsure, read our guide to bleeding and spotting in pregnancy.

What should I do if I am bleeding or suspect placenta previa?

All bleeding during pregnancy should be reported to your doctor or midwife. If the bleeding is a significant amount and is accompanied with stomach cramps, backache or contractions then you should contact the maternity section of your hospital immediately.

What will happen if I'm diagnosed with placenta previa?

If you're diagnosed with placenta previa you will be given additional ultrasounds to monitor the position of the placenta throughout your pregnancy.

Treatment of the condition will very much depend on the position of the placenta, the presence of bleeding and how severe this is.

If the bleeding is light, bed rest at home will be recommended. You will also be advised to abstain from sex and exercise as these can both cause bleeding. 

If the bleeding is heavy, you may need hospital bed rest. You may also need certain medications to prevent premature labor. 

In terms of your baby's birth, if the placenta doesn't cover your cervix, you may be able to attempt a vaginal delivery. Although most women with placenta previa near to their due date almost always give birth by Caesarean section.

This guide

This article is not meant to substitute medical advice provided by a practicing medical professional - if you have any concerns, contact your physician immediately.

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