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Polyhydramnios is the presence of too much amniotic fluid around the fetus.

Causes of polyhydramnios

  • Polyhydramnios can sometimes mean that there is a birth defect or a medical problem.
  • Birth defects that affect the baby's ability to swallow and process amniotic fluid may cause polyhydramnios. Most of these birth defects are rare, but it is important to perform a detailed ultrasound to make sure there is no evidence of these conditions. This ultrasound can detect between 50 and 75 percent of all birth defects.
  • Polyhydramnios may also be seen in conditions that cause fetal anemia, such as isoimmunization (where the mother's immune system attacks the baby's red blood cells) or certain viral infections.
  • Polyhydramnios may indicate that you have developed gestational diabetes (diabetes during pregnancy).

Diagnosing polyhydramnios

  • In early pregnancy, we can measure the depth of a pocket of amniotic fluid via ultrasound. It should be 3-8 cm. deep.
  • By about 24 weeks, the uterus has divided into four sections. We can measure the largest pocket of fluid in each section. Although a normal fluid level changes with gestational age, polyhdyramnios is typically defined as a total fluid volume of greater than 24 cm.

Impact on pregnancy

  • Most women with polyhydramnios will deliver healthy babies with no problems.
  • If polyhydramnios is severe, it may make your uterus contract. You may also find it difficult to get comfortable in a chair or lying down.

Further testing

  • If you have not been checked recently for diabetes, we can order a glucose screening test.
  • You can have a detailed ultrasound.
  • More frequent prenatal visits are often needed.
  • You may need a non-stress test, which monitors the baby's heartbeat.
  • Occasionally, amniocentesis is performed to remove some of the fluid and relieve discomfort, or to detect certain genetic conditions. 
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