What is placenta praevia?

Placenta praevia is when the placenta is either very close too, or covering your cervix.

As your pregnancy progresses your baby and placenta increase in size. Your uterus expands, and this affects the placenta's position.

The area where the placenta is attached usually stretches upwards as your uterus grows. This often moves the placenta away from your cervix. About 1 in 200 women may go on to have placenta praevia at the end of their pregnancy.

There is nothing you can do to prevent placenta praevia. However, it’s important to attend your routine antenatal appointments throughout pregnancy. Often complications can be identified during these appointments.

What causes placenta praevia?

There is no obvious cause for placenta praevia. Although, there are several factors that can increase your risk of placenta praevia. These include:

• having had a caesarean section in the past (especially if your last baby was born by caesarean)
• smoking
• older age of the mother
• having twins
• scar tissue on your uterus from past surgery

How is placenta praevia diagnosed?

Placenta praevia can be diagnosed on ultrasound.

The position of your placenta will be recorded at your 18-22 week ultrasound scan (if you choose to have this test). If your placenta is low or covering your cervix, you will be offered extra ultrasounds later in your pregnancy. This is usually at about 32 weeks. This is because the lower part of the uterus stretches as the baby grows, meaning the placenta may move higher up in the uterus as your pregnancy progresses.

Placenta praevia is often describe as; either major or minor or Grade 1,2,3 or 4. This helps your healthcare team, and you, understand the severity of the condition, or how much of the placenta is covering the cervix, with Grade 4 placenta praevia being the most serious.

Your midwife or doctor may also suspect placenta praevia if:

• You have vaginal bleeding after 20 weeks of pregnancy - this is usually painless and may happen spontaneously or after sex.
  OR
• If your baby is lying is an unusual position for example across your uterus (transverse) or bottom down (breech)

Placenta praevia is the most common cause of painless bleeding in the last trimester of pregnancy. However, there can be reasons for bleeding other than placenta praevia.

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How is placenta praevia treated?

If you have placenta praevia you and your baby will be offered more frequent monitoring during pregnancy. You may need to be cared for in a large maternity hospital and have easy access to medical support in case you start bleeding.

You will usually be offered more ultrasound scans to check on the location of your placenta. This is because the lower part of the uterus stretches as the baby grows, meaning the placenta may move higher up in the uterus as your pregnancy progresses. Knowing the exact location of your placenta helps your doctors and midwives plan and care for you and your baby safely.

If you have placenta praevia, you may need regular blood tests. Your doctor may monitor your iron levels throughout your pregnancy and you may be recommended to take iron tablets if you have anaemia (low blood haemoglobin level). You are more likely to need a blood transfusion during or after the birth.

Your baby may be monitored at times during your pregnancy with a cardiotocograph (CTG). The CTG records your baby's heart rate and response to movements and contractions. Your midwife and doctor will watch for any changes in heart rate to check your babies wellbeing.

If you experience vaginal bleeding during your pregnancy you may need to be admitted to hospital. This may be for the rest of your pregnancy. This decision will depend on your circumstances.

If you have heavy vaginal bleeding during your pregnancy, your baby may need to be delivered early (prematurely). Being in hospital doesn't stop you from bleeding, but you can get help quickly if needed.

Your obstetrician will probably advise you to have a caesarean section before your due date. This avoids the risk of you going into labour early and bleeding.

Your doctor or midwife will discuss any test results with you and advise you on the safest pregnancy and birth options, based on your individual circumstances.

Are there complications of placenta praevia?

Placenta praevia can be serious. Complications can include:

• severe blood loss
• emergency caesarean
• blood transfusion
• premature birth
• hysterectomy (removal of the uterus)

Placenta praevia can also be associated with placenta accreta.

Where can I get more information about placenta praevia?

To learn more, you can contact:

• The Australian Birth Trauma Association offers advice, resources, and a peer support service.
• The Centre of Perinatal Excellence (COPE) provides information and a list of support services.
• Perinatal Anxiety & Depression Australia (PANDA) — call 1300 726 306 to speak with a counsellor. They are available Monday to Friday, from 9am to 7.30pm Australian Eastern Time.