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What to Know About Polyhydramnios

Reviewed by Mahammad Juber, MD on April 09, 2022

Amniotic fluid is a liquid that surrounds and protects your baby in the womb. When there’s too much amniotic fluid in your womb, though, that condition is called polyhydramnios. It can cause complications during pregnancy

Here’s everything you need to know, including the symptoms, treatment, and causes of polyhydramnios.

What Is Amniotic Fluid?

Inside the womb, your baby floats, rests, and grows in a tissue sac that is called the amnion or amniotic sac. The amniotic sac contains a clear fluid known as amniotic fluid. It is essential for your baby’s development and nourishment. 

How Much Amniotic Fluid Is Normal?

About 800 milliliters of amniotic fluid collect in the amniotic sac by 34 weeks of pregnancy, but the amount of amniotic fluid decreases to about 600 milliliters by 40 weeks of pregnancy. Sometimes, you may have too little or too much amniotic fluid. Oligohydramnios is a condition that occurs when you have too little amniotic fluid, and polyhydramnios occurs when you have too much.

What Is Polyhydramnios?

Polyhydramnios makes the womb larger than normal. It can affect your pregnancy. 

Polyhydramnios can occur as early as 16 weeks of pregnancy, but it mostly happens in the later weeks of pregnancy. It is a rare condition seen in only 1% to 2% of pregnancies.

What Are the Causes of Polyhydramnios?

It’s difficult to find out the exact cause of polyhydramnios during pregnancy, but common polyhydramnios causes include:

  • A birth defect affecting the baby's digestive or nervous system
  • Problems in the baby’s stomach
  • High blood glucose levels during pregnancy or gestational diabetes
  • Carrying identical twins with twin-to-twin transfusion syndrome — a complication where one twin has too much blood and the other has too little
  • A lack of red blood cells in the baby or fetal anemia
  • Problems with the placenta, which is an organ that provides food and oxygen to the baby
  • A difference in blood type between the mother and baby
  • Infection during pregnancy
  • Heart rate problems in the baby

What Are Polyhydramnios Symptoms?

If your belly enlarges a lot in a short duration, you may have polyhydramnios. Polyhydramnios symptoms occur because excess fluid increases the pressure on the womb and surrounding organs.

If you have mild polyhydramnios, you’ll see few symptoms. Severe polyhydramnios symptoms, on the other hand, include:

  • Enlargement of the womb 
  • Tightness in the stomach
  • Indigestion
  • Constipation
  • Breathing problems
  • Swelling in the hips, thighs, legs, or feet
  • Uterine discomfort or contractions
  • Fetal malposition, where the baby moves into the wrong position in the womb
  • Trouble feeling the baby in the womb

What Are the Complications of Polyhydramnios?

If you get severe polyhydramnios in the early weeks of pregnancy, you’re at a higher risk of complications. Polyhydramnios may lead to the following complications:

How Is Polyhydramnios Diagnosed?

If you have polyhydramnios symptoms, your doctor will use an ultrasound to check how deep the amniotic fluid is in your womb. They use the following methods to diagnose polyhydramnios: 

  • Maximum vertical pocket (MPV) or Amniotic fluid volume (AFV). MPV or AFV measures the largest, deepest pocket of fluid around your baby in the womb. If the value is equal to or greater than 8 centimeters, you have polyhydramnios.
     
  • Amniotic fluid index (AFI).AFI measures the largest, deepest pocket of fluid in four areas of your womb. If the sum of these four values is more than 24 or 25 centimeters, you have polyhydramnios.

Your doctor may also use a detailed ultrasound to rule out birth defects and complications. They may do other tests to diagnose polyhydramnios:

  • Blood tests. These are done to check for infections and diseases that may cause polyhydramnios.
     
  • Amniocentesis.Amniocentesis is a procedure where your doctor will remove amniotic fluid from the womb using a needle. They check the fluid using tests as it can provide important information about your baby's health.

If you have polyhydramnios, your doctor will monitor your pregnancy using:

  • Nonstress test. This checks your baby's heart rate when they move in the womb. Your doctor will place a device on your abdomen to measure your baby's heart rate.
     
  • Biophysical profile. Your doctor uses ultrasound to check and monitor your baby's breathing and movement. They will also monitor the amniotic fluid volume in your womb.

How Is Polyhydramnios Treated?

Mild polyhydramnios may cause discomfort, but it usually doesn’t require treatment and resolves over time. Sometimes, treating the underlying cause, like diabetes, can resolve polyhydramnios.

If you have severe polyhydramnios, you may have early labor, breathing problems, or abdominal pain. In such cases, you may need immediate treatment and even hospitalization. 

Polyhydramnios treatment includes:

  • Drainage of amniotic fluid. Your doctor will drain the excess amniotic fluid from your womb. They may use amniocentesis to remove the fluid. However, the drainage procedure has some risk of complications such as early labor, detachment of the placenta, and rupture of the amniotic sac.
     
  • Medicines. Your doctor may prescribe oral medicines such as indomethacin (Indocin). It helps reduce your baby’s urine production and amniotic fluid levels. However, it must be taken before 31 weeks of pregnancy. 

The medicine, though, may present a risk of heart problems in your baby. Your doctor will monitor your baby’s heart using an echocardiogram and ultrasound.  Medication may have some side effects such as nausea, vomiting, heartburn, and gastritis or inflammation in the stomach.

After polyhydramnios treatment, your doctor will continue to monitor your amniotic fluid level every few weeks.

Other Considerations

With mild polyhydramnios, you’ll be able to carry your baby to term and give birth at 39 or 40 weeks. If you have severe polyhydramnios, though, your doctor will still help you with all the information you need. They’ll check your condition and discuss the risk of complications for you and your baby. They’ll also ensure you and your baby’s safety by providing the best possible care.

Show Sources

Sources:

Cleveland Clinic: “Polyhydramnios.”

March of Dimes: “Amniotic Fluid,” “Polyhydramnios.” 

Mayo Clinic: “Amniocentesis,” “Polyhydramnios.”

Mount Sinai: “Amniotic fluid.”

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