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?
High-Yield Explanation
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.