大量应用叶酸并没有使出生时患神经管缺陷的婴儿数目下降,一些研究人员认为这是因为妇女服用叶酸的时间不当试验表明,在妊娠前服用叶酸可减少神经管缺陷的危险性,包括脊柱裂、无脑和脑膨出。然而,自70年代初,神经管缺陷的发生率已开始稳定下降,1992年以后再没有明显下降。... Large doses of folic acid have not reduced the number of babies born with neural tube defects at birth, some researchers believe is due to the improper timing of women taking folic acid Tests show that taking folic acid before pregnancy reduces the risk of neural tube defects, including spina bifida , No brain and encephalocele. However, since the early 1970s, the incidence of neural tube defects has begun to decline steadily, with no significant decline after 1992. ...