Excess amniotic fluid surrounding the fetus during pregnancy. It occurs in about 1 in 250 pregnancies and often has no known cause. The condition sometimes occurs if the fetus has a malformation that makes normal swallowing impossible, or if the pregnant woman has diabetes mellitus. The excess amniotic fluid usually accumulates in the 2nd half of pregnancy, producing symptoms from about week 32. The main symptom is abdominal discomfort. Other possible symptoms are breathlessness and swelling of the legs. The uterus is larger than would usually be expected. Occasionally, fluid accumulates rapidly, causing abdominal pain, breathlessness, nausea, and vomiting, and leg swelling. Premature labour may result. The condition is usually evident from a physical examination, but ultrasound scanning may be needed. In mild cases, only rest is needed. In more severe cases, amniotic fluid may be withdrawn using a needle. In late pregnancy, induction of labour may be performed.


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