The mortality rate (stillbirths and infant deaths) from anencephalus from 1950-1969 in 36 cities of over 50,000 population in Canada showed a negative association (r = -.39) with the concentration of magnesium in water sampled at domestic taps. The mortality rates showed negative associations with mean income and longitude, and a multiple regression model using the three factors showed significant effects of each and accounted for 69% of the intercity variation in rates. There were no significant associations seen with water calcium concentration or total hardness. Income, magnesium and longitude were also negatively associated with mortality rates from spina bifida, hydrocephalus, other congenital abnormalities, and total stillbirth and infant death rates, but the association with magnesium was significant only for total stillbirths. The negative association of anencephalus mortality and magnesium levels was also seen in a sample of 14 smaller towns in Ontario.
Investigators estimate that the population exposure that resulted from the Chernobyl fallout is in the range of natural background radiation for most European countries. Given current radiobiologic knowledge, health effects-if any-would not be measurable with epidemiologic tools. In several independent reports, however, researchers have described isolated peaks in the prevalence of congenital malformations in the cohort conceived immediately after onset of the fallout. The consistency of the time pattern and the specific types of malformation raise concern about their significance. In this study, the author summarizes findings from Turkey, Belarus, Croatia, Finland, Germany, and other countries, and implications for radiation protection and public health issues are discussed.
Information from series of cases of anencephalus and corresponding random samples of all livebirths showed that the prevalence rate at birth per 1000 livebirths for anencephalus was 4.02 in Belfast (from 1957 to 1969), compared to 1.36 in mothers of Scots-Irish origin resident in 14 selected Canadian cities (from 1950 to 1969). For each of these two populations, anencephalus was associated with the number of previous livebirths, stillbirths, and child deaths. However, these maternal factors did not account for any appreciable portion of the difference in prevalence rates between the two populations, showing that a different set of factors must cause the international difference in rates.
Questions concerning the possible association of potatoes and neural-tube defects, and an alternative hypothesis relating to maternal growth and development.
The purpose of this investigation was to examine the sex distribution of deaths from spina bifida in birth cohorts exposed and unexposed to severe periconceptional famine. For this purpose, we compared the risk of deaths from spina bifida between birth cohorts exposed and unexposed to the Dutch Hunger Winter of 1944-1946. In males, the relative risk of death from spina bifida was 2.62 [95% confidence interval (CI) = 1.14-6.01]. In females, the relative risk for spina bifida was 0.59 (95% CI = 0.14-2.37). The sex ratio (male:female) for deaths from spina bifida in the exposed birth cohort was 2.74; a female predominance was not seen in any other birth cohort. Deaths from anencephaly and other central nervous system disorders did not exhibit this male predominance in the exposed birth cohort. These findings indicate that severe periconceptional nutrient deficiency may have a greater effect on the occurrence of spina bifida in males vs females. Other potential explanations include sex-specific effects of prenatal famine on prenatal or postnatal survival rates of cases.
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.
