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Placenta praevia (low-lying placenta)

Placenta praevia is a complication that can happen during pregnancy. It's also known as 'low-lying placenta'. It is not common.

Placenta praevia happens when the placenta (afterbirth) is partially or completely blocking off your cervix (the neck of your womb). This can lead to heavy bleeding in pregnancy or during childbirth.

If you have placenta praevia, your baby will probably be delivered by caesarean section. You'll also need to take extra care during your pregnancy.

Contact your maternity unit or hospital immediately if you have been told you have placenta praevia and have:

  • any vaginal bleeding
  • abdominal pain
  • contractions

How you'll know if you have placenta praevia

The position of the placenta will be recorded at your ultrasound scan around weeks 18 to 22 of pregnancy. If you have a low-lying placenta it will be diagnosed at this stage.

For 9 in every 10 women, a low-lying placenta will move up into their womb and won't affect them during childbirth. They will have a normal placenta by the time of their follow up scan, in the 3rd trimester.

If the placenta is still low-lying in the 3rd trimester, this is called a placenta praevia. 1 in 200 women are affected by placenta praevia at this stage.

Some women may also have a scan to check for placenta praevia if they develop signs and symptoms later in their pregnancy. These scans will look at the distance of the placenta from the entrance to the cervix.

Signs and symptoms of placenta praevia

Placenta praevia may not cause you any symptoms. But if you do have symptoms or signs they usually include:

  • vaginal bleeding in the second or third trimesters or after sex. You don’t usually have any pain with this bleeding but it can be heavy. This could put your baby at risk.
  • your baby lying in an unusual position such as breech or sideways across the womb (transverse lie)

Contact your GP, midwife or obstetrician immediately if you have any bleeding during pregnancy.

If you have placenta praevia

If you have placenta praevia you may need to take extra care during your pregnancy and the birth.

You may be advised to:

  • have extra ultrasound scans to see whether your placenta has moved upwards
  • avoid sex so as to prevent more bleeding
  • take an iron supplement - this is to reduce the risk of you becoming anaemic and build up your iron levels

Early hospital admission

At week 34 of your pregnancy you may need to go into hospital until you give birth. This is so you can be treated immediately if you bleed.

You may also be given steroid injections. This is to help your baby's lung development in case they need to be delivered early.

Blood transfusions

You may need blood transfusions if you have heavy bleeding during your pregnancy or at your delivery.

If you feel you could never accept a blood transfusion, let your obstetrician, midwife and birth partner know early in your pregnancy.

Caesarean birth

You may need a caesarean section if:

  • your placenta is blocking your baby’s way out through the birth canal
  • you or your baby are at risk

Premature birth

If your baby needs to be born prematurely, they may need additional care after birth. Your baby may need to be transferred to another hospital with facilities to care for premature babies.

page last reviewed: 29/04/2021
next review due: 29/04/2024