Alternate Names

Amniotic fluid disorder; Polyhydramnios

What Is Hydramnios?

Hydramniosis a condition that occurs when too much amniotic fluid builds up during pregnancy. It is also called amniotic fluid disorder, or polyhydramnios.

What Causes Hydramnios?

Amniotic fluid is a liquid that surrounds and cushions the fetus (unborn baby) inside the uterus. It comes from the baby’s kidneys, and it goes into the uterus from the baby’s urine. The fluid is absorbed when the baby swallows it and through breathing motions.

The amount of fluid increases until the 36th week of pregnancy. After that, it slowly decreases. If the fetus makes too much urine or does not swallow enough, amniotic fluid builds up. This causes hydramnios.

What Are the Risks of Hydramnios?

Mild hydramnios may not cause any problems. Often, extra fluid that appears during the second trimester returns to normal on its own. Mild hydramnios is more common than severe hydramnios.

Hydramnios may occur in normal pregnancies with more than one baby (twins, triplets, or more).

Severe hydramnios may mean there is a problem with the fetus. If you have severe hydramnios, your health care provider will look for these problems in your fetus:

  • Birth defects of the brain and spinal column
  • Blockages in the digestive system
  • A genetic problem (a problem with the fetus’s chromosomes that is inherited)

Many times, the cause of hydramnios is not found.

How Will I Know if I Have Hydramnios?

Mild hydramnios often has no symptoms. But tell your health care provider if you have:

  • A hard time breathing
  • Belly pain
  • Swelling or bloating of your belly

To check for hydramnios, your health care provider will measure your "fundal height” during your prenatal check-ups. Fundal height is the distance from your pubic bone to the top of your uterus. Your health care provider will also check your baby's growth by feeling your uterus through your belly.

Your health care provider will do an ultrasound if he or she thinks you may have hydramnios. This will measure the amount amniotic fluid around your baby.

How Is Hydramnios Treated?

Doctors may be able to treat the symptoms of hydramnios, but they cannot usually treat what caused it.

  • Your health care provider may want you to stay in the hospital.
  • Your provider may also prescribe medicine to prevent a preterm delivery.
  • He or she might remove some of the extra amniotic fluid to relieve your symptoms.

Your health care provider may also do tests to find out why you have extra fluid. These might include:

  • Blood tests to check for diabetes or an infection
  • Amniocentesis (a test that checks amniotic fluid)

Hydramnios and Your Delivery

Hydramnios may cause you to go into labor early.

It is easy for a fetus with a lot of fluid around it to flip and turn. This means there is a greater chance of being in a feet-down position (“breech”) when it is time to deliver. Breech babies can sometimes be moved into a head-down position, but they often have to be delivered by cesarean section.

Can I Prevent Hydramnios?

You cannot prevent hydramnios. If you have symptoms, tell your health care provider so you can be checked and treated, if needed.


Gilbert WM. Amniotic fluid disorders. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem Pregnancies. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 33.

Version Info

  • Last reviewed on 8/23/2012
  • Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch)

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.