The Effect of birth spacing on childhood mortality in Pakistan

Summary In this study retrospective data from the 1975 Pakistan Fertility Survey are used to examine the effects of birth spacing on infant and child mortality. The length of the preceding interval between live births emerges as a major determinant of mortality. The effect persists for rural and urban families, for children of uneducated and educated mothers, for both boys and girls, and for large and small families. The possibility that this relationship is the spurious consequence of data defects or of a common cause, such as early weaning, is examined but rejected. Once the length of the preceding interval is controlled, the average spacing of earlier births is found to be unrelated to survivorship. However, the length of the succeeding interval is significantly related to survivorship during the second year of life.     

Secular declines in the association between obesity and mortality in the United States

Recent research suggests that rising obesity will restrain future gains in US life expectancy and that obesity is an important contributor to the current shortfall in us longevity compared to other high-income countries. Estimates of the contribution of obesity to current and future national-level mortality patterns are sensitive to estimates of the magnitude of the association between obesity and mortality at the individual level. We assessed secular trends in the obesity/mortality association among cohorts of middle-aged adults between 1948 and 2006 using three long-running US data sources: the Framingham Heart Study, the National Health and Nutrition Examination Survey, and the National Health Interview Survey. We find substantial declines over time in the magnitude of the association between obesity and overall mortality and, in certain instances, cardiovascular-specific mortality. We conclude that estimates of the contribution of obesity to current national-level mortality patterns should take into account recent reductions in the magnitude of the obesity and mortality association.     

Teachers and the birth rate

A theoretical model is developed in which the market for teachers is linked to the time path of fertility in the general population. The model is simple in its components but when the components are combined they form a complex long-memory dynamic system. Simulation experiments are carried out to investigate the effects of changes in fertility rates on supply/requirements imbalances in the teachers' market, the median age of teachers, and other variables. The model (and by implication, the real-world system) is found to be highly volatile in response to fertility variations.This study was supported by a grant from the Social Sciences and Humanities Research Council of Canada. The authors are grateful for the able research assistance provided by Guy Brockington and Renqun Wang and for the helpful comments of the referees.     

Infant mortality and birth intervals

Summary In the course of a demographic inquiry which also offered medical advice to the respondent women, information was obtained on the reproductive life and child mortality of women in three regions of Upper Volta. Foetal mortality rates are inversely correlated with fertility rates, whereas the opposite holds true of the mortality of children aged up to four years. An explanation of this phenomenon is attempted, showing how large variations in mortality rates continue to exist in developing countries. The second section of the paper deals with spontaneous abortions which happen much more frequently than is believed in Black Africa and with the effect of pathological sterility on birth intervals. Account is taken of the taboo on sexual relations after children have been born, a taboo which continues to be kept in the region studied and which as an important effect on inter-birth intervals.     

High foetal mortality and birth intervals

Abstract Studies of birth intervals have generally separated the process into: (1) the period of infertility following a pregnancy termination; (2) the length ofthe interval from the end of the infertile period to the next conception (which reflects the probability of conception), and (3) the average duration of pregnancy for both live births and foetal deaths.(1) Empirically derived intervals between successive live births average from 19 to 30 lunar months(2) (Table 1), depending upon the population studied and the birth order.(3) Estimates of conception rates using birth intervals data require some estimate of the extent to which foetal wastage increases the birth interval.     

A study on the effectiveness of sterilizations in reducing the birth rate

This study analyzed 1,081 women in Kerala State (India) who were either sterilized or were the wives of sterilized men, and by examining the fertility among a comparable group of 1,000 other women, estimated the number of prevented future births per 1,000 women in the sterilized group. The results of this estimation were then applied to project what the entire savings in births might be over a 3D-year period in the entire Kerala population if each year there were one, three, or five sterilizations performed per 1,000 of total population. The results failed to confirm the hope that the crude birth rate would be decreased by 12 per 1,000 in a decade merely by sterilization of five per 1,000 of the population per annum. The study also discusses various measures of reduction in the crude birth rate. By a reasonable measure, the reduction in the crude birth rate for Kerala from such a sterilization program is estimated as seven points after a decade or nine points after three decades, reflecting decreases of 21 and 36 per cent, respectively, in the number of births.     

Assessing the effects of intermediate variables on birth interval-specific measures of fertility

This paper proposes a technique to simultaneously assess the effect of selected intermediate variables on the dynamics of birth intervals and to aggregate such effects across births of different order. The essentials, virtues and limitations of other approaches are 1st summarized. A method to link measures of birth interval dynamics to aggregated measures of fertility such as the age-specific fertility rates and total fertility is explained. A set of operations is suggested, required to translate estimates of birth interval-specific effects of intermediate variables into aggregate effects (e.g., effects at the level of fertility rates). These operations effectively permit the synthesis of results from multivariate procedures and those of techniques aimed at decomposing the effects of intermediate variables. Discussed are estimation and measurement procedures to deal with deal available from retrospective interviews carried out as part of the World Fertility Survey (WFS) program. The effects of marriage pattern are not considered. The effects of lactation are measured by using a dichotomous variable with a value of 1 if the preceding child was breast fed for at least as long as 9 months less than the beginning of the segment of interest and 0 otherwise. Following the assignment of a measure of effectiveness, 3 groups are distinguished in measuring contraceptive use: non-contraceptors, those using an ineffective method, and effective contraceptors. With respect to measuring the effects of induced abortion and spontaneous fetal losses, a variable is created indicating whether or not a birth leading to a fetal loss or the fetal loss itself had occurred within the segment being examined. 2 indicators, 1 a binary variable and the other aimed at measuring gradations of sterility are introduced to measure exposure to intercourse and sterility. Logit regression coefficients for selected intermediate variables are presented for Peru. The tables reveal the power of the variables measuring contraception. The evidence offers strong indications to support the contention that some form of birth control makes a difference as it does to confirm a priori expectations about success of different types of users. The inhibiting effects of breast feeding are generally in the direction expected but they are not always statistically significant. They appear to be stronger at higher parities and more intense in the earlier parts of the birth intervals. The effects of the variable representing continuity of marital union are surprisingly strong and significant for all segments of 10 months of width and for all births of order higher than 1.     

Assessment of health status of population in north and west Poland on the basis of measures related to pollution and degradation of environment. Trends in mortality

"The objective of this study is to make a cross-sectional assessment of the health status of the population inhabiting West and North Poland, using a set of negative measures of health related to the intensity of environmental factors, and to evaluate mortality trends in the same area that express changes in the rate of morbidity leading to death....The measures assumed in the analysis suggest that the population inhabiting 15 voivodeships in West and North Poland is characterised by a poorer health status than in the other area, both urban and rural."     

A simplified robust estimate of the birth rate

It is shown that other estimates of the birthrate can be derived from Coale's robust birthrate estimate. Coale's estimate is nearly equal to the birthrate obtainable from reverse survival or reverse projection of the proportion of a population under age 15 (both sexes), or C(15), using a life table corresponding to l5. As a sequel to this, a birth rate estimate was obtained that does not require reference to stable population models and results in computational economy and ease. Taking advantage of the strong linear relation between l5 and 15L0, a simple robust estimate was derived of the birthrate that does not depend upon model stable populations or model life tables. After presenting these methods, their use is illustrated with data from several Asian and African countries. Coale (1981) suggested using the observed C(15) for both sexes and l5 to locate an appropriate stable population from a family of stable models to represent the observed population and to use its birthrate as an estimate of the population under study. The estimate of l5 can be obtained by any of the indirect methods like the Brass method. Coale observed that such methods yield birthrates that are not much affected even when the populations are not stable. He also suggested an adjustment for the stable birthrate for nonstability. To obtain the birthrate, one needs the denominator, namely, the number of persons that lived. This is obtained by using the rate of increase, r, which differs for a stable and a nonstable or observed population. Various methods can be used to obtain the time reference of the mortality estimate, l5, by providing years prior to the survey or census to which the l5 estimate is applicable.     

Siblings’ neonatal mortality risks and birth spacing in Bangladesh

This paper studies the familial association of neonatal mortality in Matlab, Bangladesh and its relationship to birth-spacing effects on mortality. Findings show that familial association is strongest for siblings of adjacent birth orders. Moreover, birth-spacing effects on neonatal mortality are stronger when the preceding child has survived the neonatal period than when it has died. Transitional (Markov), random-effects, and marginal models for correlated data are introduced, and are contrasted in interpretation and technique. Familial association of neonatal mortality can be approximated well by a first-order Markov model using generalized estimating equations (GEE) to allow for higher-order correlation.     

江苏太仓市低人口生育率原因剖析

江苏太仓持续降低的人口生育率引起人口学界越来越多学者的关注。该地区低人口生育率并不是人口生育过程中的波动造成的,而是呈现出比较稳定的逐年下降的趋势。本文通过历史数据剖析了该地区低人口生育率的成因,并依据在该市的实地调研数据,剖析太仓市妇女二胎生育意愿,预测未来太仓未来人口生育率的变动。     

A study on mortality rates and expectation of life at birth in demography]

An "age-time-area diagram" (referred to as a-t diagram) which is used as the basis for discussing different used and applications of variously defined mortality rates, as well two kinds of measurements for life expectancy is proprosed. The proposal is built upon the Lexis diagram. The a-t diagram is used to define a new way of measuring child mortality, projecting population, and proposing a formula for measuring successive and nonsuccessive life expectancy.     

Premature birth and the changing composition of newborn infectious disease mortality: Reconsidering “exogenous” mortality

Linked death and birth records from San Antonio, Texas reveal that infectious infant mortality is increasingly a function of premature birth and low birth weight. Between 1935 and 1944, 4% of infectious infant deaths had associated causes involving prematurity and related conditions; by 1980, 25% of infectious infant deaths involved prematurity and more than 40% of those infants weighed less than 2,500 grams. The shift in birth-weight composition results almost entirely from an increase in very low-weight births. Under conditions of advanced perinatal technology, infectious infant mortality should no longer be viewed as wholly exogenous. These findings further undermine the contemporary relevance of the exogenous-endogenous distinction.     

新疆人口出生率的差异及其变动特征解析

新疆维吾尔自治区由于特殊的地理位置造成地区间、城乡间经济发展水平参差不齐,复杂的民族成分也使得各民族间的生育观念反差很大,这必然导致地区间、城乡间、民族间、季节间的出生率存在差异。本文汇总了新疆历年来人口出生率的数据,详细分析了出生率的变动特征和不同民族、城乡、地区、季节间出生率的历史变动规律。     

A preliminary analysis of the high birth rate in India]

The author first provides some basic demographic data for India and points out that the current annual rate of population growth of 2.45 percent is slightly higher than the annual increase in food production. Problems in the areas of employment, education, housing, and transportation, as well as the general problem of poverty, are seen as a consequence of this imbalance. The lack of success of the national family planning program is attributed primarily to the failure to achieve a satisfactory rate of economic growth. Contributory factors include early marriage, the low status of women, the desire for large families, and administrative problems associated with the family planning program.     

Adolescent social isolation and premature mortality in a Swedish birth cohort

Research shows consistently that social ties are important for longevity, and they may be particularly important during adolescence. An absence of social ties, or social isolation, during adolescence may adversely affect long-term health and wellbeing. While prior research has examined associations between isolation from friends and long-term health, and having no siblings and mortality, no study (of which we are aware) considers jointly both the role of having no friends and no siblings, nor more generally with whom adolescents spend time, and the risk of premature mortality. This paper extends the literature by drawing on data from the Stockholm Birth Cohort Study to examine the association between different types of social isolation during adolescence (i.e., an absence of friends, siblings, and time with other adolescents) and the risk of premature mortality by midlife. Results suggest that having no siblings, being unliked at school, and spending (mostly) no time with other adolescents, increases the risk of premature mortality. The association between being unliked and premature mortality was attenuated by demographic and adolescent characteristics. Consistent with our expectations, net of a robust set of covariates, adolescents who had no siblings and mostly spent no time with other adolescents (i.e., isolates) were the group most vulnerable to premature mortality by midlife. However, this was only true for females.

     

Childhood mortality,family size and birth order in pre-industrial Europe

Demography - Based on parish registers, demographic histories of Crulai (France), Tourouvre-au-Perche (France), and Geneva (Switzerland) established the childhood mortality experienced by complete...     

Effect of aggregation on the estimation of trend in mortality

"There are three approaches to analyzing and forecasting age-specific mortality: (1) analyze age-specific data directly, (2) analyze each cause-specific mortality series separately and add the results, (3) analyze cause-specific mortality series jointly and add the results. We show that if linear models are used for cause-specific mortality, then the three approaches often give close results even when cause-specific series are correlated. This result holds for cross-correlations arising from random misclassification of deaths by cause, and also for certain patterns of systematic misclassification....The results are illustrated with U.S. age-specific mortality: (1) analyse age-specific mortality data from 1968-1985. In some cases the aggregate forecasts appear to be the more credible ones." This is a revised version of a paper originally presented at the 1990 Annual Meeting of the Population Association of America (see Population Index, Vol. 56, No. 3, Fall 1990, p. 407).     

Effect of aggregation on the estimation of trend in mortality

There are three approaches to analyzing and forecasting age‐specific mortality: (1) analyze age‐specific data directly, (2) analyze each cause‐specific mortality series separately and add the results, (3) analyze cause‐specific mortality series jointly and add the results. We show that if linear models are used for cause‐specific mortality, then the three approaches often give close results even when cause‐specific series are correlated. This result holds for cross‐correlations arising from random misclassification of deaths by cause, and also for certain patterns of systematic misclassification. It need not hold, if one or more causes serve as “leading indicators”; for the remaining causes, or if outside information is incorporated into forecasting either through expert judgment or formal statistical modeling. Under highly nonlinear models or in the presence of modeling error the result may also fail. The results are illustrated with U.S. age‐specific mortality data from 1968–1985. In some cases the aggregate forecasts appear to be the more credible ones.     

Ambient temperature,birth rate,and birth outcomes: evidence from South Korea

Population and Environment - The effects from rising temperatures, a symptom of climate change, have become a significant concern. This study finds that one additional day with a maximum...