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Low Amniotic Fluid (Oligohydramnios):
What It Is, Causes and Treatment

While your baby is busy wriggling and somersaulting inside your bump, they are being supported by amniotic fluid. The amount of this liquid you are carrying around during your pregnancy varies from week to week, but sometimes you might find you have too much (polyhydramnios) or too little (oligohydramnios).

What is Amniotic Fluid?

The liquid in your amniotic sac protects your baby from any potential infections or accidental knocks along the way, while also helping your little one's digestive system and lungs to develop.


Your baby also likes to swallow the amniotic fluid before weeing it back out again, so the liquid level in your womb can change throughout the day. It also fluctuates throughout your pregnancy – you’ll start with hardly any, and it’ll build up gradually.


By the time you’re 36 weeks pregnant, you should be carrying around the added weight of about 800ml (1.4 pints) to 1,000ml (1.6 pints) of amniotic fluid. This will then start to slowly decrease as your baby gets ready to make their grand entrance.

Low Amniotic Fluid (Oligohydramnios) in Pregnancy

If your tummy or baby seems small for your dates, your midwife might want to check to make sure your amniotic fluid isn’t a little on the low side.


You’ll have a scan, and the sonographer will take a few measurements. They’ll be looking to see whether your levels of amniotic fluid are in the expected range for your stage of pregnancy.

Problems Linked to Low Amniotic Fluid (Oligohydramnios)

In early pregnancy, oligohydramnios can increase the risk of miscarriage, or stillbirth. It can also cause problems with how your baby grows or develops. Fortunately, you have many healthcare professionals on hand to recognise and monitor the condition as early as possible.


Most cases of oligohydramnios occur in the third trimester, and sometimes can lead to labour complications. This could mean that your baby is unable to move from the breech (head up) position, into the head down position.


If your waters have broken early, there is an increased risk of infection, or premature labour. Your baby could also become stressed when they’re being born. If this occurs, your doctor and midwife will want to keep a close eye on you and perform a few extra checks to see if you need a helping hand during labour, such as a caesarean.

What Are the Causes of Oligohydramnios?

Low amniotic fluid is often due to your waters breaking. Other causes include:


  • Being more than 42 weeks pregnant
  • A problem with the placenta
  • A problem with your baby’s kidneys (this would usually be picked up in your 20 week scan)
  • A problem with identical twins
  • Some types of medication, such as ibuprofen or drugs to treat high blood pressure
  • Dehydration

What to Do If You Have Low Amniotic Fluid

It can be a little scary being told you have low amniotic fluid. However, it's always best to know if there’s a problem, so your doctor can give you and baby all of the care you need.


Here's a few tips you can try if you do get told you have low amniotic fluids: