Effects of early-life conditions on adult mortality: a review

"This paper considers the effects of health conditions in childhood on an individual's mortality risks as an adult. It examines epidemiologic evidence on some of the major mechanisms expected to create a linkage between childhood and adult mortality and reviews demographic and epidemiologic studies for evidence of the hypothesized linkages....Many empirical studies support the notion that childhood conditions play a major role in adult mortality, but only in the case of respiratory tuberculosis has the demographic importance of a specific mechanism been established by cohort studies. One's date and place of birth also appear to be persistently associated with risks of adult death in a wide variety of circumstances. An individual's height, perhaps the single best indicator of nutritional and disease environment in childhood, has recently been linked to adult mortality, especially from cardiovascular diseases. Further research is needed, however, before causal mechanisms can be identified."     

The implications of increased survivorship for mortality variation in aging populations

The remarkable growth in life expectancy during the twentieth century inspired predictions of a future in which all people, not just a fortunate few, will live long lives ending at or near the maximum human life span. We show that increased longevity has been accompanied by less variation in ages at death, but survivors to the oldest ages have grown increasingly heterogeneous in their mortality risks. These trends are consistent across countries, and apply even to populations with record-low variability in the length of life. We argue that as a result of continuing improvements in survival, delayed mortality selection has shifted health disparities from early to later life, where they manifest in the growing inequalities in late-life mortality.     

Gender differences in the link between childhood socioeconomic conditions and heart attack risk in adulthood

A growing body of evidence shows that childhood socioeconomic status (SES) is predictive of disease risk in later life, with those from the most disadvantaged backgrounds more likely to experience poor adult-health outcomes. Most of these studies, however are based on middle-aged male populations and pay insufficient attention to the pathways between childhood risks and specific adult disorders. This article examines gender differences in the link between childhood SES and heart attack risk trajectories and the mechanisms by which early environments affect future disease risk. By using methods that model both latent and path-specific influences, we identify heterogeneity in early life conditions and human, social, and health capital in adulthood that contribute to diverse heart attack risk trajectories between and among men and women as they age into their 60s and 70s. We find that key risk factors for heart attack operate differently for men and women. For men, childhood SES does not differentiate those at low, increasing, and high risk for heart attack. In contrast, women who grew up without a father and/or under adverse economic conditions are the most likely to experience elevated risk for heart attack, even after we adjust for the unequal distribution of working and living conditions, social relationships, access to health care, and adult lifestyle behaviors that influence health outcomes.     

Religion and Health in Early Childhood: Evidence from South Asia

This article studies early childhood health in India, Bangladesh, and Nepal, focusing on inequalities in anthropometric outcomes by religious adherence. India and Nepal have Hindu majorities, while Bangladesh is predominantly Muslim. The results suggest that Muslim infants have an advantage over Hindu infants in height‐for‐age in India (for boys and girls) and in Bangladesh (for boys). However, this advantage disappears beyond 12 months of age, at which point Hindu children in all three countries are found to have significantly better anthropometric outcomes than Muslim children. We report tests that rule out mortality selection and undertake falsification and robustness exercises that confirm these findings. Further results suggest that exposure to Ramadan fasting in utero may lead to positive selection of Muslim male infants, partially explaining the Muslim infant health advantage, but this does not fully explain the shift from Muslim advantage in infancy to Hindu advantage in childhood in all three countries.     

The influence of cause-specific mortality conditions on the age pattern of mortality with special reference to Taiwan

Abstract This paper discusses the relationship between the level of mortality at ages one to four, on one hand, and five to 34 on the other. This relationship has been observed to vary considerably among mortality schedules at different levels of mortality and even among schedules at the same general level of mortality. This variation is shown among the modem life table systems of the Regional Model Life Tables and the United Nations Model Life Tables. Controlling for the leyel ofmortality from age five to age 34, the West Tables and the United Nations Tables embody approximately the same 'average' relationship between early childhood and adult mortality. Relatively to this average relationship, the South and East Tables consistently display higher childhood mortality rates for a given level of adult mortality. Indeed, the childhood rates of the South Table are twice those of the West Tables over a range of life expectancy at birth from 40 to 70 years. The relationship between childhood and adult mortality from 1957 to 1968, a period of rapid mortality decline, was investigated in Taiwan. In 1957, the Taiwanese data reflected the severe childhood mortality of the South Model Tables. However, by 1968, due to an especially large decline in childhood mortality, this relationship was more moderate and resembled the mortality pattern of the West or East Model Tables. An analysis of the decline in cause-specific mortality during the period revealed that a dramatic decline in childhood mortality from gastro-enteritis was primarily responsible for the shift in the relationship between childhood and adult mortality in Taiwan. It is asserted that, while any of several diseases which result in fatalities primarily among children of pre-school ages, could cause relatively severe childhood mortality, gastro-enteritis is likely to be a primary contributor to such an age pattern. This assertion is based on the fact that, especially in the developing areas of the world, malnutrition and gastro-enteritis are usually precipitating and complicating factors of other childhood diseases. A limited test of this hypothesis was provided by considering the causal components of childhood mortality rates in two populations known, for certain periods, to have exhibited relatively severe childhood mortality conditions; Spain and Portugal. For the years in which those populations were characterized by the South mortality pattern, gastro-enteritis was a principal cause of mortality in childhood. Moreover, with the decline in mortality from gastro-enteritis, the mortality pattern in Spain and Portugal no longer exhibited childhood mortality rates which were severe relative to those of adult life. The implications of these findings for the analysis of mortality conditions in many areas of the developing world, where the gastro-enteritis malnutrition syndrome annually claims a heavy toll of life in early childhood, are not clear. In those areas, the effect of this syndrome on the age pattern of mortality could be offset by special conditions inflating adult mortality rates. Nevertheless, in circumstances where there is evidence indicating substantial childhood mortality from this syndrome and no evidence indicating compensating severe adult mortality, there is reason to suspect that the existing mortality pattern reflects the relatively severe childhood mortality conditions of the South Model Tables. Additionally, where mortality from the gastro-enteritis malnutrition syndrome has been severe in past years, but has been reduced to low levels in recent years, it is probable that the relationship between childhood and adult mortality will shift in favour of the former - quite possibly, in the manner of Taiwan, from a South to an East or West age pattern.     

The Effects of Childhood,Adult, and Community Socioeconomic Conditions on Health and Mortality among Older Adults in China

Using a large, nationally representative longitudinal sample of Chinese aged 65 and older, this study examines the effects of childhood, adult, and community socioeconomic conditions on mortality and several major health outcomes. The role of social mobility is also tested. We find that childhood socioeconomic conditions exert long-term effects on functional limitations, cognitive impairment, self-rated health, and mortality independent of adult and community socioeconomic conditions. Achieved conditions matter for most outcomes as well, considering that adult and community socioeconomic conditions have additional impacts on health among Chinese elders. The majority of the effects of childhood conditions are not mediated by adult and community conditions. The results also show that social mobility and health in later life are linked in complex ways and that psychosocial factors have marginal explanatory power for the effects of socioeconomic conditions. Overall, this study provides new longitudinal evidence from China to support the notion that health and mortality at older ages are influenced by long-term and dynamic processes structured by the social stratification system. We discuss our findings in the context of the life course and ecological perspective, emphasizing that human development is influenced by a nexus of social experiences that impact individuals throughout life.     

Skeletal biology and the history of Native Americans and African Americans

The authors incorporate data from skeletal remains in an attempt to construct health profiles for the Amerindian population before Columbus's arrival and for the antebellum black slave populations of North America and the Caribbean. They examine the impact of poor nutrition among slaves, as evidenced in bone and tooth samples, on infant and childhood mortality, fertility, and adult mortality. They go on to suggest that the change from a hunter-gatherer life-style to a more sedentary agricultural one resulted in poorer health for the Amerindian population. However, agriculture made soft foods more available, allowing women to wean their children earlier, thus increasing overall fertility.     

Health Interventions and Health Equity: The Example of Measles Vaccination in Bangladesh

Although the existence of socioeconomic differentials in infant and childhood mortality in developing countries is well established. little consensus exists as to the most effective approaches to reducing such differentials. This article utilizes longitudinal data from the Matlab study area in rural Bangladesh to investigate the impact of an efficacious child survival intervention—measles vaccination—on reductions in gender and socioeconomic differentials in childhood mortality. The article analyzes data from 16,270 vaccinated children and randomly matched controls, and evaluates their subsequent mortality risks. Proportional hazards analysis demonstrates that unvaccinated children from very poor families face more than a threefold higher risk of subsequent early child mortality, compared to vaccinated children from families of high economic status. While measles vaccination has little impact on mortality risks among children of higher economic status, the improvement in survival among children from poorer households is pronounced. The provision of measles vaccination markedly reduces mortality risks for poorer children—from over three times higher to just over 1.5 times higher relative to vaccinated children from wealthier families. The findings of this study are evaluated in terms of the potential of child survival interventions such as measles vaccination to promote greater health equity.     

Causes and consequences of early-life health

We examine the consequences of child health for economic and health outcomes in adulthood, using height as a marker of childhood health. After reviewing previous evidence, we present a conceptual framework that highlights data limitations and methodological problems that complicate the study of this topic. We then present estimates of the associations between height and a range of outcomes—including schooling, employment, earnings, health, and cognitive ability—measured in five data sets from early to late adulthood. These results indicate that, on average, taller individuals attain higher levels of education. Height is also positively associated with better economic, health, and cognitive outcomes. These associations are only partially explained by the higher average educational attainment of taller individuals. We then use data from the National Longitudinal Survey of Youth 1979 Children and Young Adults survey to document the associations between health, cognitive development, and growth in childhood. Even among children with the same mother, taller siblings score better on cognitive tests and progress through school more quickly. Part of the differences found between siblings arises from differences in their birth weights and lengths attributable to mother’s behaviors while pregnant. Taken together, these results support the hypothesis that childhood health influences health and economic status throughout adulthood.     

Methods For Comparing The Mortality Experience of Heterogeneous Populations

Methods are presented which produce Maximum Likelihood Estimates (MLE) of the degree of heterogeneity in individual mortality risks under a variety of assumptions about the age trajectory of those mortality risks. With these estimates of the degree of population heterogeneity it is possible to adjust comparisons of mortality risks across populations for the effects of population heterogeneity, differential mortality selection, and different age trajectories of the force of mortality. These methods are demonstrated by applying a variety of standard assumptions about the age trajectory of the force of mortality to the analysis of a broad range of cohort mortality data for the U.S. and Swedish populations. The estimates of the degree of heterogeneity, produced under all of the selected force of mortality models, consistently indicated a considerable degree of heterogeneity in mortality risks.     

Effects of Childhood Mortality and Morbidity on the Fertility Transition in sub‐Saharan Africa

Child mortality rates have fallen substantially in developing countries since 1960. The expected fertility decline has followed only weakly in sub‐Saharan Africa compared to other recent and historic demographic transitions. Disease and anthropometric data suggest that morbidity remains prevalent in Africa despite child survival improvements. The uniquely high infectious disease burden among children in Africa reduces population health and diminishes the returns to human capital investment, thwarting the quantity–quality tradeoff for children that typically accompanies the mortality transition. Individual‐level data from the Demographic and Health Surveys are used to show that persistent morbidity has weakened the positive relationship between child mortality and total fertility rates throughout the region, slowing Africa's demographic transition.     

The long-term effects of poor childhood health: An assessment and application of retrospective reports

This study assesses retrospective childhood health reports and examines childhood health as a predictor of adult health. The results suggest that such reports are of reasonable reliability as to warrant their judicious use in population research. They also demonstrate a large positive relationship between childhood and adult health. Compared with excellent, very good, or good childhood health, poor childhood health is associated with more than three times greater odds of having poor adult self-rated health and twice the risk of a work-limiting disability or a chronic health condition. These associations are independent of childhood and current socioeconomic position and health-related risk behaviors.     

Model life tables: An empirical test of their applicability to less developed countries

Model life tables are commonly used for estimating various parameters of mortality of populations in developing countries with limited data. The application of the models is based on the assumption that the agemortality pattern of the population under consideration resembles one of the life tables in the models. The analysis in this paper tests the validity of this assumption for developing countries with data usable for the purpose. The major conclusion is that infant mortality in the populations analyzed is higher than predicted by the models corresponding to the levels of adult mortality of these populations. The observed discrepancy is ascribed to the selectivity involved in the construction of model life tables, which are primarily derived from the historical experience of Western countries. Populations in the currently developing countries apparently differ in the process of mortality change from those used in the models. Though the analysis is limited to a few countries and may not necessarily be true for all the less developed countries, it suggests the need for caution in the use of conventional model life tables.     

Cigarette Smoking and All-Cause and Cause-Specific Adult Mortality in the United States

This study illuminates the association between cigarette smoking and adult mortality in the contemporary United States. Recent studies have estimated smoking-attributable mortality using indirect approaches or with sample data that are not nationally representative and that lack key confounders. We use the 1990–2011 National Health Interview Survey Linked Mortality Files to estimate relative risks of all-cause and cause-specific mortality for current and former smokers compared with never smokers. We examine causes of death established as attributable to smoking as well as additional causes that appear to be linked to smoking but have not yet been declared by the U.S. Surgeon General to be caused by smoking. Mortality risk is substantially elevated among smokers for established causes and moderately elevated for additional causes. We also decompose the mortality disadvantage among smokers by cause of death and estimate the number of smoking-attributable deaths for the U.S. adult population ages 35+, net of sociodemographic and behavioral confounders. The elevated risks translate to 481,887 excess deaths per year among current and former smokers compared with never smokers, 14 % to 15 % of which are due to the additional causes. The additional causes of death contribute to the health burden of smoking and should be considered in future studies of smoking-attributable mortality. This study demonstrates that smoking-attributable mortality must remain a top population health priority in the United States and makes several contributions to further underscore the human costs of this tragedy that has ravaged American society for more than a century.     

US mortality in an international context: age variations

Compared to other developed countries, the United States ranks poorly in terms of life expectancy at age 50. We seek to shed light on the US's low life expectancy ranking by comparing the age-specific death rates of 18 developed countries at older ages. A striking pattern emerges: between ages 40 and 75, US all-cause mortality rates are among the poorest in the set of comparison countries. The US position improves dramatically after age 75 for both males and females. We consider four possible explanations of the age patterns revealed by this analysis: (1) access to health insurance; (2) international differences in patterns of smoking; (3) age patterns of health care system performance; and (4) selection processes. We find that health insurance and smoking are not plausible sources of this age pattern. While we cannot rule out selection, we present suggestive evidence that an unusually vigorous deployment of life-saving technologies by the US health care system at very old ages is contributing to the age-pattern of US mortality rankings. Differences in obesity distributions are likely to be making a moderate contribution to the pattern but uncertainty about the risks associated with obesity prevents a precise assessment.     

Early life exposures and the occurrence and timing of heart disease among the older adult Puerto Rican population

Few studies have examined the effects of early life conditions on the timing of the onset of heart disease. We use the remarkable example of a representative sample of the population of older Puerto Ricans aged 60– 74 who lived in the countryside during childhood (n = 1,438) to examine the effects of seasonal exposures to poor nutrition and infectious diseases during late gestation on the timing of the onset and the probability of ever experiencing adult heart disease. Cox and log logistic hazard models controlling for childhood conditions (self-reported childhood health status and socioeconomic status [SES], rheumatic fever, and knee height) and adult risk factors (adult SES, obesity, smoking, texercise, and self-reported diabetes) showed that the risk of onset of heart disease was 65% higher among those born during high-exposure periods compared with unexposed individuals. However, there were no significant differences in median time of onset for those ever experiencing heart disease. As a comparison, we found that there were no significant seasonality effects for those who lived in urban areas during childhood. We conclude that early exposures in utero have important ramifications for adult heart disease among the older Puerto Rican population. We show, however, that while exposure is associated with the probability of ever experiencing adult heart disease, it is not associated with the timing of onset among those who do experience it.     

Maternal Age and Offspring Adult Health: Evidence From the Health and Retirement Study

Advanced maternal age is associated with negative offspring health outcomes. This interpretation often relies on physiological processes related to aging, such as decreasing oocyte quality. We use a large, population-based sample of American adults to analyze how selection and lifespan overlap between generations influence the maternal age?Coffspring adult health association. We find that offspring born to mothers younger than age 25 or older than 35 have worse outcomes with respect to mortality, self-rated health, height, obesity, and the number of diagnosed conditions than those born to mothers aged 25?C34. Controls for maternal education and age at which the child lost the mother eliminate the effect for advanced maternal age up to age 45. The association between young maternal age and negative offspring outcomes is robust to these controls. Our findings suggest that the advanced maternal age?Coffspring adult health association reflects selection and factors related to lifespan overlap. These may include shared frailty or parental investment but are not directly related to the physiological health of the mother during conception, fetal development, or birth. The results for young maternal age add to the evidence suggesting that children born to young mothers might be better off if the parents waited a few years.     

On the Survival of Centenarians and the Span of Life

It has been argued in the literature that the observed mortality crossover among older black Americans relative to the white population is a result of ‘differential early mortality which selects the least robust persons from the disadvantaged population at relatively earlier ages so that, at advanced ages, the disadvantaged population has proportionately more robust persons’ (Kenneth G. Manton). The authors examine the plausibility of the observed black mortality crossover and the heterogeneity argument supporting its existence. In addition to citing evidence from the literature, they use life tables from various countries known to have good mortality data to explore the relation between mortality in childhood and at younger adult ages and mortality in old age for cohorts and periods. Analysis suggests that the association between childhood and old-age mortality for cohorts is positive, implying that observed mortality crossovers are produced by deficient data rather than population heterogeneity.     

Birth Intervals and Health in Adulthood: A Comparison of Siblings Using Swedish Register Data

A growing body of research has examined whether birth intervals influence perinatal outcomes and child health as well as long-term educational and socioeconomic outcomes. To date, however, very little research has examined whether birth spacing influences long-term health. We use contemporary Swedish population register data to examine the relationship between birth-to-birth intervals and a variety of health outcomes in adulthood: for men, height, physical fitness, and the probability of falling into different body mass index categories; and for men and women, mortality. In models that do not adjust carefully for family background, we find that short and long birth intervals are clearly associated with height, physical fitness, being overweight or obese, and mortality. However, after carefully adjusting for family background using a within-family sibling comparison design, we find that birth spacing is generally not associated with long-term health, although we find that men born after very long birth intervals have a higher probability of being overweight or obese in early adulthood. Overall, we conclude that birth intervals have little independent effect on long-term health outcomes.