From "prehypertension" to hypertension? Additional evidence.

PURPOSE: Recent U.S. guidelines redefining blood-pressure categories have generated a continuing controversy regarding the new "prehypertensive" category (systolic, 120-139, diastolic, 80-89), signifying heightened risk of progression to outright hypertension and a need for lifestyle changes and frequent follow-up. This study addresses an incompletely-explored empirical question: how well does prehypertension predict an early transition to hypertension? METHODS: Blood-pressure and other longitudinal data obtained from two British Health and Lifestyle Surveys conducted 7 years apart were used to form a subsample of 2048 men and women normotensive at baseline. Prehypertension was divided into subcategories: "normal" (systolic, 120-129; diastolic, 80-85) and "high normal" (systolic, 130-139; diastolic, 85-89), with "optimal" (systolic, < 120; diastolic < 80) as reference. Binomial regression was used to estimate adjusted relative risks (RR) and confidence intervals (CI) for hypertension at follow-up. This is an appropriate method (and preferable to logistic regression) when the outcome is common. RESULTS: Estimated RR for the "normal" subcategory was 2.0 (CI, 1.6, 2.6) and for "high normals," 2.9 (CI, 2.3, 3.7). Separate regressions by age bracket showed the greatest risks for high normals aged 35 to 44 years. CONCLUSIONS: The results support the hypothesized prehypertension effects, especially for younger high normals, but are more conservative than the Framingham-based estimates.

Effects of early health-insurance programs on European mortality and fertility trends.

In this study, we examined the mortality and fertility effects of the early health-insurance programs sponsored by several European governments in the course of the demographic transition. Three sets of effects were hypothesized, and tested with data for five countries, covering the 1875-1913 period. First, although initially small, the growing health-insurance coverage of national populations accelerated longer-term downtrends in mortality. It not only expanded access to health care, but also helped in disseminating health information and awareness. Second, widening coverage also had an opposite effect on fertility; by lowering the costs of bearing and rearing children, it acted to slow the ongoing downtrend in marital fertility. Third, there was a diverse set of interactions between the mortality and fertility effects. Improved prospects for the survival of infants and children weakened parents' motivation to produce "extra" offspring to offset losses to mortality and to insure against future losses. Child survival was further enhanced by longer intervals between births and fewer children per family. However, the reduced cost of children tended to dilute these antenatal effects. Our regression results supported the expected pattern of partial effects, but simulations were needed to gauge the total impacts of health-insurance. Two sets of simulations were conducted: first, historical simulations, which closely tracked the actual experience of each sample country; second, counterfactuals, in which health-insurance coverage was set at zero for the entire time period. Comparisons of the historical and counterfactual simulations clearly indicated that health-insurance accelerated the downtrend in mortality, but slightly retarded the secular decline in marital fertility. These effects varied in magnitude, but not in direction, among the sample countries.

Demographic consequences of maternal-leave programs in industrial countries: evidence from fixed-effects models.

PIP: The authors measure the effects of paid maternity leave upon infant mortality, the labor force participation of women during their prime childbearing years, and fertility rates. To reach their conclusions, they constructed a simultaneous-equations model using the individual fixed-effects method and a data set comprising 17 OECD countries and four time periods. The extension of maternal leave programs, measured in terms of duration of paid leave, is shown to reduce infant mortality, to raise rates of labor force participation for women in the prime childbearing ages, and to increase birth rates. The direct plus indirect impacts of extending maternity leave programs, as revealed by the reduced-form parameters of the authors' models, however, produce a different picture. The total impacts upon both infant mortality and female labor force participation conform closely to the structural estimates, but the impact upon birth rates almost disappears. It seems that the indirect effects of the maternal leave variable, via infant mortality and women's labor force participation, offset the directly pronatal influence. From a policy perspective, the benefits of paid maternal leave programs would seem to be unconditionally positive with respect to lowering infant mortality, and also positive with respect to raising female labor force participation. One should not, however, expect higher birth rates from such programs. The findings also suggest that maternal leave programs can facilitate some increases in women's labor force participation without incurring the reductions in fertility which would otherwise be experienced.^ieng

Landholding, rural fertility and internal migration in developing countries: econometric evidence from cross-national data.

PIP: This article examines the relationship between rural fertility and rural-urban migration and land holding patterns, using data for 26 developing countries. A 2-equation stochastic model is developed with variables for the rural total fertility rate, the average annual rate of rural-urban migration, the gross domestic product per agricultural worker, the small holder index, the concentration index, the land ownership index, agricultural density, the literacy rate, and life expectancy at birth. Regression results for the rural fertility and migration equations show that the coefficient for lagged migration is positive, as expected. The lack of an effect of literacy is surprising, and may indicate that urban-rural differentials in literacy rates vary widely across countries. The positive coefficient for rural income provides evidence of a positive income effect on fertility in rural areas. The 3 land holding variables receive strong statistical support. The urbanization variable is very powerful; studies that do not take this into account may be seriously biased. The smallholding variable is significant and positive, but the diffusion of land ownership raises fertility and rural-urban migration rates. The reduced form equation highlights both opportunities and obstacles. The statistical results provide strong support for the major hypotheses of the effects of land holding patterns on rural fertility and rural-urban migration: higher fertility is positively related to higher rates of out-migration. Higher out-migration in the previous decade means higher subsequent fertility.^ieng

Income redistribution versus accelerated economic growth: a comparison of demographic effects.

PIP: An attempt is made to identify the effects on fertility and mean expectation of life of varying rates of growth in aggregate income and of changes in the income share of the poorer segments of the population. The extent to which these effects vary among developing countries with different levels of mean income is also considered. An econometric model is developed to estimate the direction and strength of the structural relationships among the key variables, and simulation methods are used to predict the final demographic effects of altering either the growth rate or the size distribution of income. The results suggest that there is no general justification for income redistribution as a means of slowing rates of population growth in a developing country. It may be relevant in the more advanced developing countries, but even in those, more direct means (such as family planning programs, education, and health services) may be more effective. This is a revised version of a paper originally presented at the 1983 Annual Meeting of the Population Association of America (see Population Index, Vol. 49, No. 3, Fall 1983, p. 356).^ieng

Socioeconomic equity and fertility in developing countries: a block-recursive model.

PIP: The relationship between fertility and socioeconomic equity is explored by analyzing data from developing countries to assess the interaction between 4 variables: fertility, life expectancy, schooling, and income distribution. The theoretical model, based on findings of many past studies, is presented, and the results of regression analysis of fertility and socioeconomic variables are tabulated and discussed. The results indicate that life expectancy and schooling are major determinants of fertility. Income equity, contrary to expectations, did not influence fertility very much; fertility, however, did affect income equity considerably. Policy directions based on these findings are suggested and sources of data are cited.^ieng