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Hydramnios

Amniotic fluid disorder; Polyhydramnios; Pregnancy complications - hydramnios

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

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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:

Many times, the cause of hydramnios is not found. In some cases, it is linked to pregnancy in women who have diabetes or when the fetus is very large.

How Will I Know if I Have Hydramnios?

Mild hydramnios often has no symptoms. Be sure to tell your provider if you have:

To check for hydramnios, your 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 provider will also check your baby's growth by feeling your uterus through your belly.

Your provider will do an ultrasound if there is a chance that you may have hydramnios. This will measure the amount of amniotic fluid around your baby.

How is Hydramnios Treated?

In some cases, the symptoms of hydramnios can be treated but the cause cannot be treated.

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

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 C-section.

Can I Prevent Hydramnios?

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

References

Buhimschi CS, Mesiano S, Muglia LJ. Pathogenesis of spontaneous preterm birth. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 7.

Gilbert WM. Amniotic fluid disorders. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 28.

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Review Date: 10/5/2020  

Reviewed By: John D. Jacobson, MD, Professor of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda Center for Fertility, Loma Linda, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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