人们熟知的神经管的缺损(NTD)的发生率具有社会阶层的分布倾向。这一事实提示,NTD 的病因可能与营养因素有关,叶酸缺乏与人类 NTD之间可能有关的报道首先在1965年发表。新近调查发现不同阶层妇女在妊娠头三个月里摄入的食物不同。妊娠头三个 It is well-known that the incidence of neural tube defects (NTD) has a social-class distributional tendency. This fact suggests that the etiology of NTD may be related to nutritional factors, and the possible link between folic acid deficiency and human NTD was first published in 1965. A recent survey found that women of different social groups consumed different foods during the first trimester of pregnancy. The first three pregnancies