Polyhydramnios (pol-e-hi-DRAM-nee-os) is the buildup of increased amniotic fluid — the fluid that surrounds the baby in the uterus during pregnancy. Polyhydramnios happens in about 1% to 2% of pregnancies.

Most of the time, the condition is mild. It's often found during the middle or later stages of pregnancy. Severe polyhydramnios may cause shortness of breath, preterm labor or other symptoms.

If you learn that you have polyhydramnios, your health care team carefully tracks your pregnancy to help prevent health problems. Treatment depends on how serious the condition is. Mild polyhydramnios may go away on its own. Severe polyhydramnios may need to be watched more closely by your care team.


Polyhydramnios symptoms may be linked with the buildup of amniotic fluid creating pressure within the uterus and on nearby organs. Mild polyhydramnios often causes few or no symptoms. But serious forms of the condition may cause:

  • Shortness of breath or not being able to breathe.
  • Swelling in the ankles or feet.
  • Pain in the stomach area.
  • Feelings of tightness in the muscles of the uterus, called contractions.

Your health care professional also may also suspect polyhydramnios if your uterus has become large for the number of weeks of pregnancy.


Some of the known causes of polyhydramnios include:

  • Conditions that affect the baby's digestive tract, central nervous system or certain other organs.
  • Genetic conditions that affect the baby.
  • Diabetes in the pregnant person.
  • A complication of identical twin pregnancies in which one twin receives too much blood and the other too little. This is called twin-to-twin transfusion syndrome.
  • A decreased amount of red blood cells in the baby, also called fetal anemia.
  • A condition in which the pregnant parent's blood cells attack the baby's blood cells.
  • Infection during pregnancy.

Often, the cause of polyhydramnios isn't clear, especially when the condition is mild.

Risk factors

Risk factors for polyhydramnios include certain conditions that develop during pregnancy, such as gestational diabetes. A condition that affects the developing baby, such as a problem with the digestive tract, central nervous system or other organs, may also put you at risk of polyhydramnios.


Polyhydramnios is linked with:

  • The baby being born too early, also called premature birth.
  • The baby not being head-down in the ideal position before delivery, also called a breech birth.
  • The water breaking early, also called premature rupture of membranes.
  • The baby's umbilical cord dropping into the vagina ahead of the baby, also called umbilical cord prolapse.
  • The organ that provides oxygen and nutrients to the unborn baby, the placenta, peeling away from the inner wall of the uterus before delivery. This is called placental abruption.
  • Need for a C-section delivery.
  • Pregnancy loss after 20 weeks, also called stillbirth.
  • Heavy bleeding due to decreased uterine muscle tone after delivery.

Greater health problems usually are linked with severe polyhydramnios.