Spina bifida is caused by the failure of the neural tube to close during the first month of embryonic development (often before the mother knows she is pregnant).
Normally the closure of the neural tube occurs around 28 days after fertilization. It is unknown how or why folic acid has this effect.
Spina bifida does not follow direct patterns of heredity like muscular dystrophy or haemophilia. Studies show that a woman who has had one child with a neural tube defects such as spina bifida, have about a three percent risk of having another child with a neural tube defect. This risk can be reduced to about one percent if the woman takes high doses (4 mg/day) of folic acid before and during pregnancy. For the general population, low-dose folic acid supplements are advised (0.4 mg/day).
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"Spina Bifida"
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