Bound J P, Harvey P W, Brookes D M, Sayers B M
J Epidemiol Community Health. 1981 Jun;35(2):102-5. doi: 10.1136/jech.35.2.102.
In an area which had a high incidence of anencephalus, 3.2 per 1000 births, there was a significant drop to 1.3 per 1000, below the national average of 1.7 to 1.8, among conceptions after 1967. In the northern part of the area this drop was greater in summer than winter conceptions, providing additional evidence of a different process underlying case occurrences in the north of the area from that in the south. In 1957-61 there were significantly more births of anencephalic babies in North Fylde than in South Fylde, but both areas were supplied with soft water. From 1962 to 1969 the water changed from soft to slightly hard. Soft water does not appear to be a primary aetiological factor in anencephalus, but hard water may mitigate the effect of other factors.
在无脑儿发病率较高的一个地区，即每1000例出生中有3.2例无脑儿，1967年以后受孕的婴儿中，无脑儿发病率显著下降至每1000例中有1.3例，低于全国平均水平1.7至1.8例。在该地区北部，夏季受孕的无脑儿发病率下降幅度大于冬季受孕的情况，这进一步证明该地区北部与南部无脑儿病例发生的潜在过程不同。1957 - 1961年，北费尔德出生的无脑儿婴儿显著多于南费尔德，但两个地区都供应软水。1962年至1969年，水质从软水变为微硬水。软水似乎不是无脑儿的主要病因，但硬水可能减轻其他因素的影响。
