Polyhydramnios is too much fluid in the amniotic sac. The amniotic sac is the “water bag” inside the womb that protects your baby. Usually, there is about 1 liter of fluid by 36 weeks of pregnancy. Polyhydramnios is defined as a measurement, called the amniotic fluid index (AFI), of greater than 25 cm. About 2% of pregnant women have more than 25 cm and have polyhydramnios. Increased amniotic fluid can indicate a problem in the mother or the baby. It can also cause the following:

  • Early labor and delivery
  • Cesarean delivery
  • Increased bleeding after delivery
  • Reduced growth in the baby

Fetus in Utero, Amniotic Fluid

© 2009 Nucleus Medical Art, Inc.


About two-thirds of the time, the cause of polyhydramnios is unknown. One-third of the time a cause is found. Some causes are related to the mother, and others are related to the baby.

Conditions that can cause polyhydramnios:

  • Birth defects (anencephaly)
  • Rh disease (a treatable condition that occurs when mother and baby have different blood types)
  • Diabetes in the mother
  • Identical twins (twin-to-twin transfusion)

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. The presence of a known cause of polyhydramnios—such as diabetes in the mother—increases the risk of developing it.


Symptoms in the mother:

  • Discomfort in the abdomen
  • Trouble breathing due to crowding of the lungs

However, women with mild polyhydramnios may have no symptoms.


Your doctor will ask about your symptoms and medical history, and perform a physical exam. You will probably be referred to a doctor who specializes in obstetrics.

Tests may include the following:

  • Ultrasound —a test that uses sound waves to examine your uterus (womb) and baby
  • Amniotic fluid index—shows the amount of amniotic fluid based on the ultrasound picture. More than 25 cm means you have polyhydramnios.
  • Blood glucose—a blood test to check for diabetes
  • Amniocentesis —a test in which some amniotic fluid is removed for chromosome analysis to check for birth defects


You will probably have more frequent prenatal visits and regular ultrasound tests. It is very important to keep these appointments.

About half the time, polyhydramnios gets better without any treatment at all. In other cases, treating the cause of the increased amniotic fluid takes care of the problem. For example, diabetes treatment may make the polyhydramnios go away.

Your doctor will suggest a treatment plan based on your due date and the amount of amniotic fluid. If treatment is needed, options include the following:

Removal of Amniotic Fluid

Your doctor may perform amnioreduction to remove some amniotic fluid. This is similar to amniocentesis, but more fluid is removed.


A medication may be used to decrease amniotic fluid. It is effective about 90% of the time, but cannot be used in the last eight weeks of pregnancy.


The only way to prevent polyhydramnios is to treat its causes if possible. Getting regular check-ups while you’re pregnant can help find the problem early.