International journal of epidemiology
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A case-control study of fatal venous thromboembolism in young women is described. Sixty women aged between 16 and 39 who died from thromboembolism in England and Wales between 1986 and 1988 were included in the study. Two living controls matched for age and marital status were sought from the records of the general practitioner with whom each case was registered. ⋯ These risks are considerably smaller than those observed in previous studies. The observed risk may be low because the dosage of oestrogen in modern oral contraceptive preparations has been reduced, but it may also be because the cases of fatal venous thromboembolism included in this study represent only a small proportion of all cases of venous thrombeombolism; a disease which is rarely fatal in young women. These results cannot necessarily be extrapolated to nonfatal venous thromboembolism.
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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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A re-analysis of the data from 11 case-control studies was performed to investigate the association between head trauma and Alzheimer's disease (AD). To increase comparability of studies, exposures were limited to head trauma with loss of consciousness (hereafter referred to as 'head trauma') and comparisons were restricted to community (versus hospital) controls. Test for heterogeneity across studies was negative; consequently, data were pooled in subsequent analyses. ⋯ There was no interaction effect between head trauma and family history of dementia, suggesting that these risk factors operate independently. Mean age of onset was not significantly different in cases with a history of head trauma compared to cases without such a history. The findings of the pooled analysis support an association between reported head trauma and AD.