Elwood J M
Br J Prev Soc Med. 1976 Mar;30(1):29-31. doi: 10.1136/jech.30.1.29.
The hypothesis proposed by Knox (1970) that an anencephalic fetus arises from a fetus-fetus interaction between two dizygous twins predicts that the twinning rate, the population incidence of anencephalus, and the female proportion of anencephalics in a population should be positively interrelated. These associations were tested using Canadian data during a long period of time and over a large geographical area. The results did not support the hypothesis.
诺克斯（1970年）提出的假说认为，无脑儿胎儿源于两个异卵双胞胎之间的胎儿-胎儿相互作用，该假说预测，双胞胎发生率、无脑儿在人群中的发病率以及人群中无脑儿的女性比例应呈正相关。利用加拿大在很长一段时间内和大面积地理区域的数据对这些关联进行了检验。结果不支持该假说。
