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What is it? What are the symptoms? What are the treatments?

What is polyhydramnios?

Polyhydramnios is the medical term for having too much amniotic fluid in the amniotic sac in pregnancy. It's relatively rare, occurring in less than one per cent of pregnancies in the UK, but usually starts from around week 30. The amount of fluid round your baby gradually increases throughout pregnancy until there is 800-1000ml at around 36 weeks. The volume decreases from this point onwards.

In polyhydramnios there can be as much as 3000ml of fluid in the amniotic sac. It's not always clear why some mums-to-be have more fluid than others, but it can be down to several factors. Sometimes it indicates a problem with the baby; it could be the placenta not working properly, or it could indicate a health problem in the mum. The sorts of factors that have been linked with polyhydramnios include:

  • poorly controlled diabetes in the expectant mum. This can make your baby pass more urine than is normal, increasing the volume of fluid surrounding him
  • some infections, including rubella (German measles), toxoplasmosis and others
  • having a multiple pregnancy
  • a congenital problem with the baby's nervous system, kidneys or heart or a chromosomal abnormality, such as Down's or Edwards' syndrome
  • a problem with the arteries in the umbilical cord or a tumour on the placenta, although both of these conditions are very rare.

All of this sounds worryingly serious, but do be reassured that the majority of expectant mums with polyhydramnios go on to have perfectly healthy babies. If you're found to have polyhydramnios, you'll first be tested for diabetes. Most cases of diabetes in pregnancy are controlled by following a strict low-sugar, low-fat diet. Once your blood-sugar levels are under control, the amount of amniotic fluid will reduce as your baby won't be weeing as much.

You'll also have scans to keep an eye on your baby's wellbeing. If all's well with your baby, tests will be run to check for possible infection. Whatever the outcome, you'll be monitored more closely for the rest of your pregnancy, so make sure you keep all your antenatal appointments. Around 20% of mums with polyhydramnios go into premature labour (before week 37) as a result of the excess fluid, so it's important to be on the alert for signs of early labour. If it does happen, ring your maternity unit immediately and let them know you're coming in as an emergency. If necessary, call an ambulance.

You'll be monitored closely throughout labour and delivery, especially as there's a chance of the umbilical cord coming down in front of your baby and getting compressed. When this happens, it normally always results in a emergency caesarean. There's also a chance the placenta will detach from the wall of the uterus if the fluid volume reduces very suddenly. If you've been found to be diabetic, your baby is likely to be larger than expected, so your medical team will want to monitor his progress.

What are the symptoms of Polyhydramnios?

Your bump may feel too big, with stretched, shiny skin, and you might feel more breathless than usual. Some women have abdominal pain, which should always be reported to a midwife or doctor. A lot of the other symptoms of polyhydramnios are common in pregnancy anyway, so self diagnosis isn't really possible. They include constipation, varicose veins and heartburn. The condition will picked up when your midwife measures your bump and finds that you are 'large for dates'. In this case, you'll be referred for a scan to measure the amount of amniotic fluid you have.

What are the treatments and remedies of Polyhydramnios?

Mostly, expectant mums with polyhydramnios are advised to rest and to avoid activities that make them breathless. In some cases, a drug might be prescribed to reduce the amount of urine the baby passes. If you have severe polyhydramnios, you may need some of the amniotic fluid to be drained off to reduce the risk of premature labour or problems with the placenta. The procedure itself can be risky, though, sometimes causing infection, bleeding and problems with the placenta, so in most cases expectant mums are advised to take early maternity leave and rest as much as possible. Remember: the majority of mums with polyhydramnios give birth to perfectly healthy babies.

This guide 

The information in this Bounty A-Z of Family Health is not a substitute for an examination, diagnosis or treatment by a doctor, midwife, health visitor or any other qualified health professional. If in doubt, always speak to a doctor.

Bounty will not be held responsible or liable for any injury, loss, damage, or illness, however this occurs or appears, after using the information given on this website and in particular the A-Z of Family Health.

Further help

For health advice and information 24 hours a day, 365 days a year, the NHS offers call and web services. You can also visit NHS websites for services, health information and health news at nhs.uk 

  • England – call 111 from any landline or mobile phone free of charge, or visit nhs.uk 
  • Scotland – call 111 from any landline or mobile phone free of charge, or visit nhs24.com 
  • Wales – call 0845 4647 , or visit nhsdirect.wales.nhs.uk 
  • Northern Ireland – visit hscni.net