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Amniotic Fluid Levels In Pregnancy

Medically Reviewed by Caitlin Goodwin, MSN, RN, CNM
What level of amniotic fluid is normal?

Amniotic fluid levels are evaluated every time an ultrasound is performed on your baby. It’s a standard way of checking on your baby’s health.

In this article, we’ll discuss what is considered normal amniotic fluid levels, and what you can do if your levels are too low or high.

What is Amniotic Fluid?

Following conception, an amniotic sac forms around the developing embryo. The sac is transparent and tough, growing as your unborn baby does. The sac increasingly fills with fluid, until around the second trimester, as the baby then takes over its production (1).

This watery substance contains essential fetal proteins and is clear in color. The baby swallows this fluid while they practicing “breathing” and excretes it again as urine.

It’s cleaned via our kidneys though, so it is not actually as disgusting as it seems.

Amniotic fluid contents are vital for a healthy developing baby, providing the ultimate protection from the outside world.

Amniotic Fluid Benefits

We know the surrounding fluid also acts as a cushion to protect our unborn baby. It also has many other functions, which is what makes it so important.

Here are just a few:

  • Water levels: Allows baby ample space for movement.
  • Temperature: Maintains a constant temperature for creating a healthy baby.
  • Aids healthy growth: Enables correct bone, muscle, and organ development.
  • Nutrient exchange: Enables vital nutrients between you and your baby, including oxygen, via the umbilical cord. If fluid levels change, the umbilical cord’s health can be compromised.

Amniotic Fluid Volume Assessment

At some point in your pregnancy, you’ll likely have an ultrasound scan, along with other tests. Particularly during your second and third trimesters, your sonographer will take detailed measurements of the amount of amniotic fluid surrounding your baby. This will be repeatedly done if your measurements are low or high or for high-risk pregnancies.

These measurements are also done as part of a fetal biophysical profile to understand your baby’s health in the uterus. Other parts of the biophysical profile include baby’s breathing, movements, and flexion. While you are just excited to see your baby waving at you from within, the sonographer will be taking down lots of information.

I’ll admit, I never really knew what my obstetrician was doing. At my first scan, all I wanted to know was if there was a heartbeat.

During your prenatal visits, you will have blood tests, bump measurements, and your blood pressure taken. The main examination in relation to your amniotic fluid levels, however, will be via a sonogram.

Sometimes, amniotic fluid levels don’t appear to be within normal limits on a scan. If the clinician has advised that your fluid levels don’t seem right, you will be followed more closely. If your doctor wants to deliver your baby early due to complications, they may perform a procedure called amniocentesis to assess fetal lung maturity.

What Happens During Amniocentesis?

Although this test may be recommended for different reasons, it is mainly to detect fetal or genetic abnormalities in your baby.

A very thin needle is inserted into the amniotic sac through your abdomen to draw out some liquid. It is then sent to a laboratory for analysis, where any chromosomal defects are picked up.

While amniocentesis is viewed as a safe test, it does have possible risks, including miscarriage (2). Although it can be difficult to determine how many miscarriages happen because of amniocentesis, it is believed to be anywhere from 1 in 200 to 1 in 400.

What Will an Ultrasound Scan Detect?

In pregnancy, an ultrasound scan is sensitive enough to detect abnormally high or low levels of amniotic fluid. It does this by emitting sound waves into the uterus through the stomach, which returns a digital screen image (3).

If your obstetrician orders a sonogram to measure fluid around the baby, they will use clinical charts. This helps to determine what they call the Amniotic Fluid Index, or AFI.

They do this by quartering the uterus (not literally!) and using the probe to measure the deepest pools of water. The measurements are taken in centimeters.

Results will be referenced in comparison to the clinician’s AFI chart. Your results, of course, will be dependent upon your current gestation at the time of the scan.

What Are Abnormal Amniotic Fluid Levels?

According to clinical guidelines, the normal index level is from 5 to 25 cm. However, average measurements can be 80 mm to 140 mm (3.15 inches to 5.5 inches) between the 5th and 8th months of pregnancy.

Excessive levels of fluid are greater than 25 cm — medically this is called polyhydramnios. Any AFI less than 5 cm are abnormal, and this is called oligohydramnios.

1. Oligohydramnios (Low Amniotic Fluid Levels)

If you have low fluid levels, there are various causes, risks, and some possible treatments to help.

Risks With Low Fluid Levels

The risks of low amniotic fluid levels in the womb include:

  • Contractures (shortening) of the limbs.
  • Clubbing of the feet and hands.
  • The potential of developing hypoplastic (underdeveloped) lungs.

When babies are born with inadequate lung capacity, they can’t get enough oxygen. This can involve serious complications and can be fatal.

What Causes It?

  • Infections.
  • Baby’s kidneys not functioning correctly or they are malformed (amniotic fluid volume is mostly urine in late pregnancy).
  • Procedures such as chorionic villus sampling (CVS). This is a test that samples placental tissue and can detect a significant amount of disorders (4).
  • Preterm premature rupture of membranes (PPROM). Basically, a medical term for preterm breaking of water.

How Is It Medically Managed?

  • Bed rest.
  • Oral fluids.
  • Intravenous hydration. This involves a short hospital stay with you on a fluid drip directly into your veins.
  • Antibiotics.
  • Steroids.
  • Amnioinfusion. This is when extra fluid is added into the amniotic sac to increase liquid levels.

Can I Do Anything to Help?

Yes, you can. Taking your physician’s advice for bed rest is key. Of course, they don’t mean staying horizontal in bed for the remainder of your pregnancy, but no strenuous activity.

Generally taking it easy is best. Increasing your fluid intake can help too, so drink plenty of water.

Hallelujah! An actual doctor’s permission to keep your feet up and watch the entire Friends collection. May even have time to fit in The Game of Thrones too with your favorite decaf on hand.

2. Polyhydramnios (High Amniotic Fluid Level)

At the opposite end of the fluid level spectrum, this is when you have way too much amniotic fluid on board. Although deemed less severe than too little amniotic liquid, it still is a complication with associated risks (5).

Risks with Excess Fluid Levels

The risks of excess amniotic fluid levels in the womb include:

  • Premature labor.
  • Difficulty breathing/shortness of breath.
  • Abnormal fetal position.
  • Umbilical cord prolapse.
  • Uterine atony (lack of muscle contractions during labor).
  • Placental abruption (separation of the uterus from the placenta).
  • Abnormal positioning of the fetus (6).

I know this is serious business, but sharing is caring! In my most recent pregnancy, I was huge, but just in the front! That was thanks to my chubby unborn, as well as some excess fluid.

My husband made me sit on a trash bag in the car for fear of flooding his precious-metal baby. After doing some reading myself about leaking fluid, there were a few emergency room visits as I was convinced I was trickling my water whenever I stood up.

You’ve probably gathered by the tone that this wasn’t actually the case. I’d just managed to pee myself. Now, that was embarrassing!

Clearly, my pelvic floor wasn’t so much a floor and more a trap door, letting my pee escape at will.

What Can Cause Polyhydramnios?

  • Maternal diabetes.
  • Carrying twins or multiple babies.
  • Fetal abnormalities, preventing baby from swallowing fluid to create urine, which is rare.
  • Fetal anemia caused by blood incompatibility, although this is also rare (7).

How Is It Medically Managed?

  • High-resolution sonograms.
  • Amniocentesis to check for infections, or to syringe out fluid. They can do this multiple times if required.
  • Non-stress tests, which monitor fetal heartbeat at rest and while moving.
  • Pharmaceutical drugs. However, clinicians have raised concerns about their side effects to the baby and mother.
  • Close monitoring.

What Can I Do?

  • Try not to worry — polyhydramnios isn’t usually a sign of something serious.
  • Keep an eye on your symptoms. If anything changes, let your obstetrician know immediately. For example, rapid growth of your bump.
  • Rest.

Unknown Causes

If the cause of the condition is unknown, then other treatments may be used. For example, there may be a suspicion there is fetal bladder obstruction.

A small tube can actually be placed in the bladder while in utero. This will start the flow of fluid in the amniotic sac.

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Amniotic Fluid FAQs

1. What If I Have Abnormal Fluid Levels?

As mentioned previously, this will all be dependent on whether your AFI is too low or high for your current gestation.

If you are told you have excess fluid in the uterus during a routine sonogram, you will be offered close monitoring of both the baby and you. You may even have fluid removed via a syringe.

If you have levels on the lower end of the scale, a hospital stay may be required for hydration, amniotic infusions, etc.

If you go into labor and have known abnormal AFI, be prepared that you may be asked to go into the hospital immediately.

2. Are There Possible Treatments?

Unfortunately, there aren’t many effective treatments for either oligohydramnios or polyhydramnios. It is usually managed conservatively, as mentioned earlier.

Do be assured that if your sonographer has any concerns during your routine checks, they know what to do. Working closely with your doctor, they sure will be doing everything they can to keep you and your little bun in the oven safe.

3. What Are Signs of Leaking Fluid?

People will probably say to you, “Don’t panic, you’ll know when it happens!” The fact is, a lot of moms, and not just first-time moms, don’t know what to expect at all.

The main sign of fluid loss is a gush or constant, continuous trickle of odorless, clear or straw-colored water. Most women have the trickling symptom rather than a large gush of fluid.

If you suspect fluid loss:

  • Write down the time it happened.
  • Try guessing how much fluid you see (such as a glass full).
  • Take note of if it’s a continuous leak, or small bits at a time.
  • Take a look at what the fluid looks like.
  • Put a pad on to easily monitor the fluid.
  • Call your doctor. This needs to be checked out.
  • Do not insert anything into the vagina.

Beware that, if a fluid leak is confirmed, your labor may start at any time. In fact, most doctors indicate that you may need to induce to deliver your baby because of the risk of infection.


From the moment you are pregnant until the moment you give birth, you will undoubtedly worry about every eventuality. Reading up too much on risks in pregnancy can drive you crazy. If you do have any concerns, never be afraid to speak with your obstetrician or midwife, who will gladly put your mind at ease.

Remember, if you are diagnosed with polyhydramnios or oligohydramnios, you can manage, but not cure the condition.

Leaking amniotic fluid comes out continuously. Urine only comes out when laughing, coughing or sneezing, and isn’t constant.

Get in touch with your health provider if you need reassurance, even if you end up embarrassed. It’s better to be safe after all!

Headshot of Caitlin Goodwin, MSN, RN, CNM

Medically Reviewed by

Caitlin Goodwin, MSN, RN, CNM

Caitlin Goodwin MSN, RN, CNM is a Certified Nurse-Midwife, clinical instructor and educator. She has ten years of nursing experience and enjoys blogging about family travel and autism in her free time.