Maclean M H, MacLeod A
J Epidemiol Community Health. 1984 Jun;38(2):99-102. doi: 10.1136/jech.38.2.99.
There have been statistically significant seasonal variations of annencephalus and spina bifida in each country of the United Kingdom during 1964-79 with the exception of anencephalus births in Northern Ireland. The seasonal peaks, where discernible, are in phase. Embryos appear to develop anencephalus most commonly in May-June and spina bifida in July.
1964年至1979年期间,除北爱尔兰无脑儿出生情况外,英国每个国家无脑儿和脊柱裂的发病率均存在统计学上显著的季节性变化。可识别的季节性高峰处于同一阶段。胚胎最常于5月至6月发育成无脑儿,7月发育成脊柱裂。