Polyhydramnios is a common complication of pregnancy, where there's an excessive amountof amniotic fluid surrounding the unborn baby (foetus).

An abnormal amount of fluid (whether increased or reduced) might be suspected by your healthcare professional after 30 weeks of pregnancy, during one of your antenatal appointments , and should be monitored and investigated.

The cause of polyhydramnios is often unknown, but sometimes indicates a problem with the baby's development (see What are the causes? , below). However, most women with polyhydramnios give birth to healthy babies.

If you're pregnant and notice your belly is getting large very quickly (acute polyhydramnios), contact your doctor or midwife. It's rare for it to happen suddenly, but it can indicate an abnormality with the foetus and increases your risk of giving birth prematurely .

This page covers:

  • How is polyhydramnios diagnosed?
  • What are the causes?
  • What associated risks should I be aware of?
  • How is it investigated and managed?
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Medically Reviewed by a doctor on 16 Jan 2017