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Polyhydramnios (too much amniotic fluid)

Polyhydramnios is when there's too much amniotic fluid (the fluid that surrounds the baby in the womb) during pregnancy. It's not usually serious and there's often no cause.

Symptoms of polyhydramnios

Polyhydramnios (too much amniotic fluid) does not usually cause symptoms. You may only find out you have it at a routine scan or antenatal appointment.

If you do have symptoms, they might include:

  • indigestion and heartburn
  • constipation
  • breathlessness
  • swollen feet and legs
  • urinary tract infections (UTIs)

These could also be usual symptoms in pregnancy.

Polyhydramnios can happen suddenly if the amniotic fluid increases quickly. It can cause tummy pain and make your tummy get bigger suddenly. This is more common if you're expecting more than 1 baby.

Urgent advice: Ask for an urgent GP appointment, contact your midwife, or get help from NHS 111 if:

  • your tummy gets bigger suddenly
  • you have tummy pain

You can call 111 or get help from 111 online.

How polyhydramnios is diagnosed

If you do not have symptoms of polyhydramnios (too much amniotic fluid), you may only find out you have it at a routine appointment.

The person doing your ultrasound scan (a sonographer) may see the extra fluid, or your midwife may notice at a check-up because you'll be larger than expected for your due date.

It may be harder to hear the baby's heartbeat at your appointments because of the extra fluid.

If you have symptoms of polyhydramnios, such as your tummy getting bigger suddenly, you may be referred for an ultrasound scan.

A sonographer will measure the amount of amniotic fluid around the baby.

How you get polyhydramnios

The cause of polyhydramnios (too much amniotic fluid) is often unknown.

Some possible causes include:

  • diabetes during pregnancy (gestational diabetes)
  • being pregnant with more than 1 baby
  • an infection during pregnancy
  • a problem with your baby swallowing
  • your baby having a genetic condition

Treatments for polyhydramnios

Polyhydramnios (too much amniotic fluid) usually does not need any treatment. You may have extra check-ups for the rest of your pregnancy and during labour and birth.

If the polyhydramnios is caused by a condition such as gestational diabetes, you'll be treated for the condition.

If you have severe polyhydramnios, you may have some of the amniotic fluid drained from your womb using a thin needle. You may need this treatment more than once. You'll be monitored afterwards to check your fluid levels.

Complications of polyhydramnios

Complications of polyhydramnios (too much amniotic fluid) are rare.

Rarely, in more severe cases, complications can include:

  • your waters breaking early – call your midwife straight away if this happens
  • placental abruption, where the placenta separates from the womb before the baby is born
  • umbilical cord prolapse, where the umbilical cord slips down in front of the baby after your waters have broken
  • your baby being born prematurely
  • your baby having a low birth weight

Your labour and birth plan

If you have moderate or severe polyhydramnios, you may be advised to give birth in hospital. This is so you can be monitored closely and treatment will be available quickly if needed.

You may have a higher chance of needing a caesarean section to avoid any problems.

Speak to your midwife if you have any concerns about your plans for labour and birth.

Page last reviewed: 18 April 2024
Next review due: 18 April 2027