Polyhydramnios is when you have too much amniotic fluid. Amniotic fluid is the fluid that surrounds your baby in your uterus (womb). It’s very important for your baby’s development.

How do you know if you have polyhydramnios?
Many women with polyhydramnios don’t have symptoms. If you have a lot of extra amniotic fluid you may have belly pain and trouble breathing. This is because the uterus presses on your organs and lungs.

Your health care provider uses ultrasound to measure the amount of amniotic fluid. There are two ways to measure the fluid: amniotic fluid index (AFI) and maximum vertical pocket (MPV).

The AFI checks how deep the amniotic fluid is in four areas of your uterus. These amounts are then added up. If your AFI is more than 24 centimeters, you have polyhdramnios.

The MPV measures the deepest area of your uterus to check the amniotic fluid level. If your MPV is more than 8 centimeters, you have polyhdramnios.

Ask your provider if you have questions about these measurements.

What problems can polyhydramnios cause?
Polyhydramnios may increase the risk of these problems during pregnancy:

  • Premature birth – Birth before 37 completed weeks of pregnancy
  • Premature rupture of the membranes (PROM) – When the amniotic sac breaks after 37 weeks of pregnancy but before labor starts
  • Placental abruption – When the placenta partially or completely peels away from the wall of the uterus before birth
  • Stillbirth – When a baby dies in the womb after 20 weeks of pregnancy
  • Postpartum hemorrhage – Severe bleeding after birth
  • Fetal malposition – When a baby is not in a head-down position and may need to be born by cesarean section

What causes polyhydramnios?
In about half of cases, we don’t know what causes polyhydramnios. In other cases, we can identify a cause. Some known causes are:

  • Birth defects, especially those that affect the baby’s swallowing. A baby’s swallowing keeps the fluid in the womb at a steady level.
  • Diabetes – Having too much sugar in your blood
  • Mismatch between your blood and your baby’s blood, such as Rh and Kell diseases
  • Twin-to-twin transfusion syndrome (TTTS) – If you’re carrying identical twins, this is when one twin gets too much blood flow and the other gets too little.
  • Problems with the baby’s heart rate
  • An infection in the baby

How is polyhydramnios treated?
When an ultrasound shows you have too much amniotic fluid, your provider does a more detailed ultrasound to check for birth defects and TTTS.

Your provider also may recommend a blood test for diabetes and an amniocentesis. Amniocentesis is a test that takes some amniotic fluid from around the baby to check for problems, like birth defects.

In many cases, slight polyhydramnios goes away by itself. Other times, it may go away when the problem causing it is fixed. For example, if your baby’s heart rate is causing the problem, sometimes your provider can give you medicine to fix it.

If you have polyhydramnios, you usually have ultrasounds weekly or more often to check amniotic fluid levels. You may also have tests to check your baby’s health.

Having too much amniotic fluid may make you uncomfortable. Your provider may give you medicine called indomethacin. This medicine helps lower the amount of urine that your baby makes, so it lowers the amount of amniotic fluid. Amniocentesis also can remove extra fluid.

If you have slight polyhdramnios near the end of your pregnancy but tests show that you and your baby are healthy, you usually don’t need any treatment.

Is polyhydramnios common?
About 1 out of 100 (1 percent) pregnant women have too much amniotic fluid. It usually happens when fluid builds up slowly in the second half of pregnancy. In a small number of women, fluid builds up quickly. This can happen as early as 16 weeks of pregnancy, and it usually causes very early birth.

Last reviewed June 2011

See also: Oligohydramnios

Most common questions

What is mononucleosis?

Mononucleosis (also called mono) is an infection usually caused by the Epstein-Barr virus (EBV). It’s sometimes caused by another virus called cytomegalovirus (CMV). EBV and CMV are part of the herpes virus family. Mono is most common in teenagers and young adults, but anyone can get it. Mono is called the “kissing disease” because it’s usually passed from one person to another through saliva. In addition to kissing, it can also be passed through sneezing, coughing or sharing pillows, drinks, straws, and toothbrushes.

You can have mono without having any symptoms. But even if you don’t get sick, you can still pass it to others. Symptoms can include:

  • Achy muscles
  • Belly pain
  • Fatigue (feeling tired all the time)
  • Fever
  • Sore throat
  • Swollen glands in your neck

If your symptoms don’t go away or get worse, tell your health care provider. He’ll most likely do a physical exam and test your blood to find out for sure if you have mono.

There’s no vaccine to prevent mono. There’s also no specific treatment. The best care is to take it easy and get as much rest as you can. It may take a few weeks before you fully recover.

Can Rh factor affect my baby?

The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.

If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.

If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.

I had a miscarriage. How long should I wait to try again?

Before getting pregnant again, it's important that you are ready both physically and emotionally. If you don't need tests or treatments to discover the cause of the miscarriage, it's usually OK for you to become pregnant after one normal menstrual cycle. However, it may take longer for you to feel emotionally ready to be pregnant again. Everyone responds differently to a miscarriage. Only you will know when you are ready to try to get pregnant again.

Are gallstones common during pregnancy?

Not common, but they do happen. Elevated hormones during pregnancy can cause the gallbladder to function more slowly, less efficiently. The gallbladder stores and releases bile, a substance produced in the liver. Bile helps digest fat. When bile sits in the gallbladder for too long, hard, solid nuggets called gallstones can form. The stones can block the flow of bile, causing indigestion and sometimes serious pain. Staying at a healthy weight during pregnancy can help lower your risk of gallstones. Exercise and eating foods that are low in fat and high in fiber, like veggies, fruits and whole grains, can help, too. Symptoms of gallstones include nausea, vomiting and intense, continuous abdominal pain. Treatment during pregnancy may include surgery to remove the gallbladder. Gallstones in the third trimester can be managed with a strict meal plan and pain medication, followed by surgery several weeks after delivery.

©2013 March of Dimes Foundation. The March of Dimes is a non-profit organization recognized as tax-exempt under Internal Revenue Code section 501(c)(3).