Polyhydramnios (pol-e-hy-DRAM-nee-os) is the excessive accumulation of amniotic fluid — the fluid that surrounds the baby in the uterus during pregnancy. Polyhydramnios occurs in about 1 percent of pregnancies.
Most cases of polyhydramnios are mild and result from a gradual buildup of amniotic fluid during the second half of pregnancy. Severe polyhydramnios may cause shortness of breath, preterm labor, or other signs and symptoms.
If you’re diagnosed with polyhydramnios, your health care provider will carefully monitor your pregnancy to help prevent complications. Treatment depends on the severity of the condition. Mild polyhydramnios may go away on its own. Severe polyhydramnios may require treatment, such as draining the excess amniotic fluid.
Some of the known causes of polyhydramnios include:
- A birth defect that affects the baby’s gastrointestinal tract or central nervous system
- Maternal diabetes
- Twin-twin transfusion — a possible complication of identical twin pregnancies in which one twin receives too much blood and the other too little
- A lack of red blood cells in the baby (fetal anemia)
- Blood incompatibilities between mother and baby
Often, however, the cause of polyhydramnios isn’t clear.
Polyhydramnios symptoms result from pressure being exerted within the uterus and on nearby organs.
Mild polyhydramnios may cause few — if any — signs or symptoms. Severe polyhydramnios may cause:
- Shortness of breath or the inability to breathe, except when upright
- Swelling in the lower extremities, vulva and abdominal wall
- Decreased urine production
Your health care provider may also suspect polyhydramnios if your uterus is excessively enlarged and he or she has trouble feeling the baby or hearing the heartbeat.