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Hydramnios is a condition during pregnancy characterized by too much amniotic fluid. It is also known as amniotic fluid disorder or polyhydramnios.


Amniotic fluid is a sterile solution that surrounds and cushions the fetus inside the uterus during pregnancy. The fluid comes from the baby’s kidneys – it's fetal urine – and is absorbed when the fetus swallows it. The amount of fluid increases until the 36th week of pregnancy; after that, it slowly decreases. If the fetus makes too much urine, or doesn’t swallow enough, too much fluid accumulates, resulting in hydramnios.

Severe hydramnios may signal a problem with the fetus, such as a central nervous system defect, a gastrointestinal blockage, or a chromosomal problem. In rare cases, it can lead to early labor or even fetal death. Mild hydramnios is more common, and doesn't signal a problem. In fact, extra fluid that appears during the second trimester is likely to return to a normal range without treatment.

How Will I Know If I Have It?

Mild hydramnios often has no symptoms. But let your doctor know if you experience breathlessness, abdominal pain, and marked swelling or bloating, which can be signs of more severe hydramnios.

During regular prenatal check-ups, your caregiver will use a tape measure or similar method to gauge your "fundal height" - the distance from your pubic bone to top of uterus. He'll also check baby's growth by simply feeling uterus through abdomen or performing an ultrasound. If he suspects hydramnios, he'll order an ultrasound, which can measure the amount amniotic fluid surrounding your baby.

How Is It Treated?

Doctors can treat the symptoms of hydramnios, but usually not whatever caused the condition itself. If you have difficulty breathing or walking, for instance, your caregiver may want to hospitalize you. And since hydramnios can lead to preterm delivery, he may put you on medications that prevent this. He may also suggest amniocentesis to remove some of the excess fluid and lessen your discomfort.

You may also undergo tests to try to determine why you have extra amniotic fluid. Your doctor may check an ultrasound to look for problems with the fetus, and an amniocentesis may be done to check for chromosome problems associated with hydramnios. She may also test your blood for diabetes and evidence of recent infections. In many cases, no explanation of the high fluid is found.

How Can I Prevent It?

You can't. Since little can be done to prevent the conditions that may lead to hydramnios, there's no way to head off the disorder itself.

Frequently Asked Questions

Q: I've heard of something called oligohydramnios. Is it the same as hydramnios?

A: No. Oligohydramnios is just the opposite - there isn't enough amniotic fluid. This condition generally occurs when something is wrong with the fetus or the placenta or when the mother has high blood pressure. The biggest danger of oligohydramnios is that, without plenty of fluid to float in, the fetus' body may compress the umbilical cord, cutting off its supply of oxygen and nutrients. If you're diagnosed with oligohydramnios, your caregiver will monitor your baby's health carefully to make sure this doesn't happen.

Q: Can hydramnios harm my baby?

A: The increased risk of preterm labor aside, hydramnios doesn't cause health problems -- it merely reflects them. If you develop severe hydramnios, your doctor will look for problems in the baby's gastrointestinal system, central nervous system, and heart, as well as chromosomal defects such as Down syndrome.

Q: If I have hydramnios, is something definitely wrong with my baby?

A: Not at all. In fact, if you develop the condition during your second trimester, chances are good that your baby is fine and that the hydramnios will disappear on its own. Hydramnios may also occur during perfectly healthy multiple pregnancies. If you're concerned, though, ask your health care provider to check for birth defects and other problems during an ultrasound.

Q: Will hydramnios cause problems with my delivery?

A: A fetus with lots of fluid around it can continue to flip and turn right up to delivery, and has a greater chance of flipping to be feet down, or breech. Breech babies can sometimes be coaxed back to the head-down position, but they often have to be delivered by c-section. Also, rarely, a condition called abruptio placenta can occur when your water bag breaks. In this condition, the placenta may separate from the uterus due to a sudden decompression, and vaginal bleeding will start. You need to contact your doctor immediately.

Updated: 12/9/2012

Irina Burd, MD, PhD, Maternal Fetal Medicine, Johns Hopkins University, Baltimore, MD. Review provided by VeriMed Healthcare Network.

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