International journal of epidemiology
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Seasonal variations in the proportion of preterm births in Japan from January 1979 to December 1983 are analysed using a traditional method of time-series analysis, which divides the variation in a series into trend, seasonal variation, other cyclic change, and remaining irregular fluctuations. It is shown that the proportion of preterm births in Japan have a clear seasonal periodicity with two peaks in summer and winter. Analysis of seasonality by period of gestation shows that interesting differences in kurtosis and skewness exist between summer and winter, i.e. the summer increase in preterm births was characterized by an increase of skewness which means an extension of the lower part of the distribution. ⋯ Theoretical simulations based on actual birth data in Japan over the period, are carried out to examine how season of conception could influence seasonal variations in the proportion of preterm births. Results show that, at least for first births, seasonality in conception rates could be one explanatory factor for the observed seasonal variation in proportions of preterm births. Another analysis reveals that conception in May and June are more likely to result in preterm births in Japan.
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The objective of the study was to relate blood pressure levels in children to their mother's weight in pregnancy. The blood pressures of 675 children aged from one to nine years in three villages in rural Gambia were measured. They were matched to antenatal clinic data which had been collected from all pregnant women in the three villages since 1980. ⋯ Rather they were inversely related to mothers' weight gain in the last trimester. An interpretation of these findings is that among young children differences in blood pressure are largely determined by rates of maturation. However, the long-term effects of adverse intra-uterine influences which elevate blood pressure become apparent in older children.
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In many developing countries even crude estimates of the level of maternal mortality are lacking and the prospects of fulfilling this need using conventional sources of vital registration and health service statistics are not encouraging. The constraint this imposes on the effective planning, management and evaluation of the programmes now being launched to reduce these neglected deaths is self-evident. It is less obvious how the majority of developing countries can be expected to meet the call for reliable estimates of maternal mortality by 1995. ⋯ In recent years the reduction of the level of maternal mortality in developing countries has become a priority for both national governments and international agencies. Attention has been drawn to the wide range of levels within and between countries and to the huge discrepancies in the lifetime risk of maternal death for women in the developed compared with the developing world. This risk has been estimated to range from 1 in 19 in West Africa to almost 1 in 10,000 in Northern Europe.
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Studies of risk factors for Alzheimer's disease have been hampered by low statistical power. The data from 11 case-control studies were pooled and re-analysed to evaluate the evidence for the association of Alzheimer's disease with family history of dementia and related disorders, parental age, medical history, and environmental factors. This paper gives a brief description of the participating studies and discusses the strategy that has been followed in the collaborative analysis.
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In the EURODEM pooling and re-analysis of case-control studies of Alzheimer's disease it has been possible to examine putative risk factors with increased power to detect associations. The fundamental problems of case and control selection persist, such as use of prevalent cases, selection through contact with specific services, difficulties of control choice. Risk factors such as family history and head trauma are shown again, although the biases introduced in collection of exposure data could still account for these findings. ⋯ Improvement of cardiovascular indices may improve the cerebrovascular status of the population, possibly reducing the incidence of vascular dementia. Other broad strategies to maintain health and function would seem prudent, but specific recommendations to reduce the incidence of Alzheimer's disease, or to slow progression of the disorder cannot be recommended on the basis of these re-analyses. It is clear that more research is needed to understand the risks of different pathologies related to Alzheimer's disease as well as dementia and cognitive change generally in the population.(ABSTRACT TRUNCATED AT 250 WORDS)