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What is hydramnios?

In this condition, there is too much amniotic fluid around your baby during pregnancy. It happens in about 1 in 100 pregnancies. It’s also called polyhydramnios.

Your baby needs amniotic fluid to grow. This watery fluid is inside the amniotic sac (membrane). It’s sometimes called the bag of waters. Your baby stays in this fluid for all of pregnancy. It helps to cushion and protect your baby. Amniotic fluid also helps your baby’s lungs, kidneys, and gastrointestinal tract grow.

The fluid is made by your baby’s lungs and kidneys. Your baby swallows the fluid and passes it out as urine. The waste is taken away through your placenta.  

Pregnant women normally have about 1 pint to 1 quart (500 to 1,000 ml) of amniotic fluid. Too much or too little amniotic fluid can cause problems. These issues can affect how your baby develops. They can also cause pregnancy complications. Or the amount of amniotic fluid may be a sign of another issue.

What causes hydramnios?

This condition may happen for several reasons. Either too much fluid is made or there’s a problem with the fluid being taken away. Or both of these things may be happening. Hydramnios may be caused by diabetes in the mother.

It can also be caused by problems with the developing baby. These can include:

  • Digestive problems that block fluid

  • Problems with swallowing that may be due to a central nervous system problem or chromosome issues

  • Twin-to-twin transfusion syndrome, a condition where identical twins share a placenta

  • Heart failure

  • Infection

What are the symptoms of hydramnios?

Symptoms can occur a bit differently in each pregnancy. They can include:

  • Fast growth of your uterus

  • Stomach discomfort

  • Uterus that is larger than normal for how far along you are in pregnancy

  • Labor pains (contractions)

The symptoms of this health problem may be like symptoms of other conditions. See your healthcare provider for a diagnosis.

How is hydramnios diagnosed?

Your healthcare provider will look at your health history. They will also give you an exam. A healthcare provider may spot this condition on an ultrasound during pregnancy. They will measure pockets of fluid to check the amount. In some cases, an ultrasound can help find the cause of hydramnios. These can include a multiple pregnancy or a birth defect.

How is hydramnios treated?

The goal of treatment is to keep you pregnant for as long as it’s safe. Treatment may also make you more comfortable.

Treatment will depend on your symptoms, pregnancy, and general health. It will also depend on how severe the condition is. Treatment may include:

  • Closely watching the amount of amniotic fluid you have. Your healthcare provider will check this at your visits.  

  • Medicine. This can reduce how much urine your baby makes. This can lower the amount of fluid.

  • Removing some of the amniotic fluid. This is done by inserting a needle through your uterus and into the amniotic sac. This is called amnioreduction with amniocentesis. You may need to have this done more than once.

  • Delivery. If problems are too risky for you or your baby, you may need to deliver your baby early.

What are possible complications of hydramnios?

Too much amniotic fluid can cause your uterus to become too large. This may lead to preterm labor. Or the amniotic sac may break too early.

This condition is also linked with birth defects. When the sac breaks, large amounts of fluid leave the uterus. This may cause the placenta to detach from your uterus too early (placental abruption). It may also cause the umbilical cord to fall into your vagina (umbilical cord prolapse).

Key points about hydramnios

  • Hydramnios occurs when there’s too much amniotic fluid around your baby during pregnancy.

  • It can be caused by problems in both the mother and baby.

  • It causes the uterus to grow fast.

  • Your healthcare provider may spot this condition during an ultrasound in pregnancy.

  • Treatment will depend on the amount of extra fluid you have. It will also depend on other factors.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember what your provider tells you.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your healthcare provider if you have questions.

Medical Reviewers:

  • Donna Freeborn PhD CNM FNP
  • Heather M Trevino BSN RNC
  • Irina Burd MD PhD