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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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During her eighth month of pregnancy, a 29-year-old woman is noted to have polyhydramnios. Further testing shows anencephalus. Polyhydramnios in this patient is caused by which of the following?
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The correct answer is  Anencephalus is due to failure of the cephalic part of the neural tube to close off. This condition happens in 1/1000 pregnancies, is four times more common in whites than blacks, and is four times more common in females than males.