Homocysteine can get build up in the newest bloodstream when there is ineffective folate and/or supplement B Neural tube defects (NTD) may result in anencephaly or spina bifida, which are mostly fatal congenital malformations of the central nervous system. The defects arise from failure of embryonic neural tube to close, which occurs between the 21 st and 28 th days after conception, a time when many women are unaware of their pregnancy (38).