本文是在英国的黑兹,贝尔发斯特,曼切斯特,赤斯特,伦敦和利物浦六个研究中心协作完成的,在总共154例补充维生素的母亲中有292例(64％)来自位于英格兰东南的伦敦和北爱尔兰的贝尔发斯特。从这两地方提供病人是很有意义的,因为英国的北爱尔兰和英格兰东南分别是神经管缺损(NTD)发病率高与低的两个极端流行区。 This article was done in collaboration with six research centers in Hertz, Belfast, Manchester, Chester, London and Liverpool in the United Kingdom. Of a total of 154 mothers with vitamin supplements, 292 (64%) were from Belfast in London in southeast England and Northern Ireland. It is instructive to provide patients from these two places because the two extreme epidemic areas of high and low incidence of neural tube defects (NTD) in Britain, Northern Ireland and South East of England, respectively.