Need to talk? Call 1800 882 436.
It's a free call with a maternal child health nurse. *call charges may apply from your mobile

Is it an emergency? Dial 000
If you need urgent medical help, call triple zero immediately.

beginning of content

Amniotic fluid

4-minute read

What is amniotic fluid?

Amniotic fluid is the liquid that surrounds your baby in the uterus during pregnancy. It is contained in the amniotic sac.

How is amniotic fluid produced?

Amniotic fluid starts to form in the first few weeks of pregnancy.

Your baby produces most of this fluid themselves through their urine and lung secretions. The amount of amniotic fluid around your baby usually increases throughout pregnancy and is thought to reach its highest amount (volume) early in the third trimester.

Why is amniotic fluid important during pregnancy?

Amniotic fluid has a few important functions that help to support your baby’s growth and development.

The amniotic fluid helps:

  • your baby to move around in your uterus
  • your baby’s lungs, digestive system and muscles to develop
  • maintain a normal temperature around your baby
  • cushion and protect your baby and their umbilical cord from pressure or outside injury

How is amniotic fluid assessed?

Amniotic fluid can be assessed and measured using ultrasound. The ultrasound probe will be placed on your tummy and the healthcare professional will look for pockets of amniotic fluid around your baby.

Once these pockets of fluid are found, the depth of the fluid is measured to give an indication of the overall fluid volume. The amount of fluid is usually described in centimetres.

What do the results of this test mean?

The amount of amniotic fluid around your baby provides some information about your baby’s wellbeing. Too much or too little fluid can be associated with pregnancy complications and can sometimes signal that there is a problem.

For this reason, the amount of amniotic fluid is often measured during your routine pregnancy ultrasounds.

How much fluid is normal?

The amount of amniotic fluid that you can expect in pregnancy depends on how many weeks pregnant you. The amount will vary from person to person and in each pregnancy.

How much amniotic fluid is considered normal varies a lot, and the reference range used to determine this depends on how your healthcare provider does the assessment.

For this reason, it’s best to speak with your midwife or doctor to understand the assessment and results.

What if the amount of fluid is not normal?

In a small number of pregnancies, the amount of fluid around the baby may be higher or lower than expected. This may be because of a pregnancy complication and can sometimes indicate that there is a problem, although in some cases a cause may not always be found.

  • Oligohydramnios is the medical term used to describe having low or not enough amniotic fluid.
  • Anhydramnios is the medical term used to describe when there is no amniotic fluid seen on an ultrasound.
  • Polyhydramnios is the medical term used to describe having too much or more fluid than expected.

What a high or low fluid volume means for you and your baby depends on a number of factors, including the cause (if known), the severity of the finding and how far along you are in your pregnancy.

If you have an amniotic fluid volume that is considered too high or too low, your doctor or midwife will explain what this means for you, including the likely causes and how to manage this.

If the amniotic fluid volume is not within the expected range, it is very likely that you have not done anything to cause this. However, keeping healthy and active in pregnancy will help both you and your baby.

Speak to a maternal child health nurse

Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: November 2022

Back To Top

Need more information?

Pregnancy tests amniocentesis - Better Health Channel

Amniocentesis is a prenatal procedure performed on a pregnant woman to withdraw a small amount of amniotic fluid from the sac surrounding the fetus.

Read more on Better Health Channel website

Ultrasounds during pregnancy | Health and wellbeing | Queensland Government

Ultrasounds use sound waves to create an image (picture) of your baby. They are used to look at your developing baby.

Read more on Queensland Health website

Women's Health - InsideRadiology

InsideRadiology provides free and easily accessible, accurate, up to date and credible information about medical imaging tests and procedures.

Read more on InsideRadiology website

Amniocentesis - InsideRadiology

InsideRadiology provides free and easily accessible, accurate, up to date and credible information about medical imaging tests and procedures.

Read more on InsideRadiology website

Pregnancy tests - ultrasound - Better Health Channel

Ultrasound is used during pregnancy to check the baby's development and to help pick up any abnormalities.

Read more on Better Health Channel website

Giving birth - waters breaking

Waters breaking is when the amniotic sac holding your baby breaks and amniotic fluid leaks from your vagina. It's a sign your baby will be born soon.

Read more on Pregnancy, Birth & Baby website

Morphology scan

You will be offered a morphology scan at week 18 to 22 of pregnancy. Learn what a morphology scan can tell you and how this ultrasound test is done.

Read more on Pregnancy, Birth & Baby website

Nuchal translucency scan

A nuchal translucency scan is an ultrasound scan that helps in work out your risk of having a baby with chromosomal abnormality like Down syndrome.

Read more on Pregnancy, Birth & Baby website

Amniocentesis: what you need to know -

Amniocentesis is a test that can be done in pregnancy. It is possible to tell from the test whether the fetus has certain birth defects.

Read more on MyDoctor website

Maternal screening | Pathology Tests Explained

The maternal serum screening tests involve the measurement of different pregnancy-associated hormones, which are found in all pregnancies. 

Read more on Pathology Tests Explained website

Call us and speak to a Maternal Child Health Nurse for personal advice and guidance.

Need further advice or guidance from our maternal child health nurses?

Healthdirect Australia acknowledges the Traditional Owners of Country throughout Australia and their continuing connection to land, sea and community. We pay our respects to the Traditional Owners and to Elders both past and present.

This information is for your general information and use only and is not intended to be used as medical advice and should not be used to diagnose, treat, cure or prevent any medical condition, nor should it be used for therapeutic purposes.

The information is not a substitute for independent professional advice and should not be used as an alternative to professional health care. If you have a particular medical problem, please consult a healthcare professional.

Except as permitted under the Copyright Act 1968, this publication or any part of it may not be reproduced, altered, adapted, stored and/or distributed in any form or by any means without the prior written permission of Healthdirect Australia.