Does exposure to infectious diseases in infancy affect old-age mortality? Evidence from a pre-industrial population

Vestiges of famine: Long-term mortality impacts of early-life exposure to the 1840s famine in Estonia

The paper investigates whether exposure to a famine in the Russian Tsarist Province of Livland in 1844-1846 in early life negatively affected survival at later ages, using individual data from two rural parishes. We follow 18 birth cohorts born between 1834-1852 until age 75 and differentiate between timing and length of exposures. We find that relative to individuals born in pre- or post- crisis years, there were no significant differences in survival from age 21-75. Cohorts with longer exposure to famine conditions had increased mortality only in short term, up to age 20. Males were more vulnerable in younger ages than females. The negative effect of adverse early life exposure on survival in later life was constrained to lower social group - the landless, but for the better-off groups the effect was constrained to younger ages. The paper highlights the importance of accounting for sex and socio-economic differences in studies exploring the effects of early life conditions on later-life survival.

The Long Harm of Childhood: Childhood Exposure to Mortality and Subsequent Risk of Adult Mortality in Utah and The Netherlands

How do early-life conditions affect adult mortality? Research has yielded mixed evidence about the influence of infant and child mortality in birth cohorts on adult health and mortality. Studies rarely consider the specific role of mortality within the family. We estimated how individuals' exposure to mortality as a child is related to their adult mortality risk between ages 18 and 85 in two historical populations, Utah (USA) 1874-2015 and Zeeland (The Netherlands) 1812-1957. We examined these associations for early community-level exposure to infant and early (before sixth birthday) and late (before eighteenth birthday) childhood mortality as well as exposure during these ages to sibling deaths. We find that that exposure in childhood to community mortality and sibling deaths increases adult mortality rates. Effects of sibling mortality on adult all-cause mortality risk were stronger in Utah, where sibling deaths were less common in relation to Zeeland. Exposure to sibling death due to infection was related to the surviving siblings' risk of adult mortality due to cardiovascular disease (relative risk: 1.06) and metabolic disease (relative risk: 1.42), primarily diabetes mellitus, a result consistent with an inflammatory immune response mechanism. We conclude that early-life conditions and exposure to mortality in early life, especially within families of origin, contribute to adult mortality.

The Impact of Parental Death in Childhood on Sons' and Daughters' Status Attainment in Young Adulthood in the Netherlands, 1850-1952

Previous research on the impact of parental loss on labor market outcomes in adulthood has often suffered from low sample sizes. To generate further insights into the long-term consequences of parental death, I use the Historical Sample of the Netherlands (HSN). The HSN contains occupational information on life courses of a sample of more than 8,000 males and almost 7,000 females born between 1850 and 1922, a period of important labor market transformations. Roughly 20 % of the sample population experienced parental death before age 16. Linear regression models show that maternal loss is significantly associated with lower occupational position in adulthood for both men and women, which points to the crucial importance of maternal care in childhood for socioeconomic outcomes in later life. This interpretation is supported by the finding that a stepmother's entry into the family is positively related with sons' occupational position later in life. In contrast to expectations, the loss of economic resources related to the father's death is generally not associated with lower status attainment in adulthood for men or for women. The results indicate, however, that the negative consequences of paternal death on men's socioeconomic outcomes decreased over time, illustrating the complex interaction between individual life courses and surrounding labor market transformations.

Using Geographic Distance as a Potential Proxy for Help in the Assessment of the Grandmother Hypothesis

Life-history theory predicts that selection could favor the decoupling of somatic and reproductive senescence if post-reproductive lifespan (PRLS) provides additional indirect fitness benefits [1, 2]. The grandmother hypothesis proposes that prolonged PRLS evolved because post-reproductive grandmothers gain inclusive fitness benefits by helping their daughters and grandchildren [3, 4]. Because most historical human data do not report direct evidence of help, we hypothesized that geographic distance between individuals may be inversely related to their capacity to help. Using an exceptionally detailed dataset of pre-industrial French settlers in the St. Lawrence Valley during the 17^th and 18^th centuries, we assessed the potential for grandmothers to improve their inclusive fitness by helping their descendants, and we evaluated how this effect varied with geographic distance, ranging between 0 and 325 km, while accounting for potential familial genetic and environmental effects [5-9]. Grandmothers (F0) who were alive allowed their daughters (F1) to increase their number of offspring (F2) born by 2.1 and to increase their number of offspring surviving to 15 years of age by 1.1 compared to when grandmothers were dead. However, the age at first reproduction was not influenced by the life status (alive or dead) of grandmothers. As geographic distance increased, the number of offspring born and lifetime reproductive success decreased, while the age at first reproduction increased, despite the grandmother being alive in these analyses. Our study suggests that geographic proximity has the potential to modulate inclusive fitness, supporting the grandmother hypothesis, and to contribute to our understanding of the evolution of PRLS.

Early Plasmodium-induced inflammation does not accelerate aging in mice

Aging is associated with a decline of performance leading to reduced reproductive output and survival. While the antagonistic pleiotropy theory of aging has attracted considerable attention, the molecular/physiological functions underlying the early-life benefits/late-life costs paradigm remain elusive. We tested the hypothesis that while early activation of the inflammatory response confers benefits in terms of protection against infection, it also incurs costs in terms of reduced reproductive output at old age and shortened longevity. We infected mice with the malaria parasite Plasmodium yoelii and increased the inflammatory response using an anti-IL-10 receptor antibody treatment. We quantified the benefits and costs of the inflammatory response during the acute phase of the infection and at old age. In agreement with the antagonistic pleiotropy hypothesis, the inflammatory response provided an early-life benefit, since infected mice that were treated with anti-IL-10 receptor antibodies had reduced parasite density and anemia. However, at old age, mice in all treatment groups had similar levels of C-reactive protein, reproductive output, survival rate, and lifespan. Overall, our results do not support the hypothesis that the benefits of a robust response to malaria infection in early life incur longer term fitness costs.

Comparing Observed and Unobserved Components of Childhood: Evidence From Finnish Register Data on Midlife Mortality From Siblings and Their Parents

In this study, we argue that the long arm of childhood that determines adult mortality should be thought of as comprising an observed part and its unobserved counterpart, reflecting the observed socioeconomic position of individuals and their parents and unobserved factors shared within a family. Our estimates of the observed and unobserved parts of the long arm of childhood are based on family-level variance in a survival analytic regression model, using siblings nested within families as the units of analysis. The study uses a sample of Finnish siblings born between 1936 and 1950 obtained from Finnish census data. Individuals are followed from ages 35 to 72. To explain familial influence on mortality, we use demographic background factors, the socioeconomic position of the parents, and the individuals' own socioeconomic position at age 35 as predictors of all-cause and cause-specific mortality. The observed part-demographic and socioeconomic factors, including region; number of siblings; native language; parents' education and occupation; and individuals' income, occupation, tenancy status, and education-accounts for between 10 % and 25 % of the total familial influence on mortality. The larger part of the influence of the family on mortality is not explained by observed individual and parental socioeconomic position or demographic background and thus remains an unobserved component of the arm of childhood. This component highlights the need to investigate the influence of childhood circumstances on adult mortality in a comprehensive framework, including demographic, social, behavioral, and genetic information from the family of origin.

Epidemic cycles and environmental pressure in colonial Quebec

OBJECTIVES

Research on historical populations in Europe finds that infectious disease epidemics appear to induce predictable cycles in age-specific mortality. We know little, however, about whether such cycles also occurred in less dense founder populations of North America. We used high-quality data on the Quebecois population from 1680 to 1798 to examine the extent to which age-specific mortality showed predictable epidemic cycles. We further examined whether environmental pressures-temperature, lack of precipitation, or crop failure-may have set the stage for the emergence of epidemics.

METHODS

We applied autoregressive, integrated, moving average time series methods to annual counts of period mortality for the following age groups: < 1 year, 1 to < 5 years, 5 to < 15 years, 15 to < 50 years, and 50 years and above. These methods controlled for other patterns (e.g., trend) before empirically identifying cycles.

RESULTS

Results indicate a strong seven-year cycle in mortality among infants and children under seven years of age. Warm temperatures (across Quebec overall) and relatively dry years (in Eastern Quebec) also predicted an increased risk of mortality in infancy and childhood, although these environmental variables appear to act independently of the epidemic cycle pattern.

DISCUSSION

Findings indicate a strong seven-year epidemic cycle in historical Quebec which afflicted naïve birth cohorts not previously exposed to the prior epidemic. We contend that smallpox epidemics likely contributed to this cycle. The seven-year cycle occurred only in the latter half of the test period (post 1740) with increasing size of the colony and population concentration in urban areas.

The effect of disease burden on the speed of aging: an analysis of the Sardinian mortality transition

According to the constant senescence hypothesis, senescence cannot be accelerated or decelerated by exogenous factors. Two contrasting theories have been proposed in the literature. According to the inflammaging theory, those individuals who have experienced a higher antigenic load will experience more rapid senescence. Instead, the calorie restriction theory stresses that excessive daily calorie intake can produce an acceleration in senescence.

To test these theories, this paper analyzes the evolution of the rate of aging in Sardinia (Italy). In this population, the epidemiological transition started without any substantial modification in nutritional levels. This allows us to test the constant senescence hypothesis against the inflammaging theory, without the possible confounding effect produced by the nutrition transition.

To accomplish this aim, the longitudinal life tables from 80 years onwards for Sardinian cohorts born between 1866 and 1908 were reconstituted. They were then used to estimate the rate of aging by means of the Gamma-Gompertz model. Coherently with the inflammaging theory, the results show that the Sardinian population experienced a dramatic decrease in the rate of aging that coincided with the onset of the epidemiological transition.

Immigrants’ Health in Europe: A Cross-Classified Multilevel Approach to Examine Origin Country, Destination Country, and Community Effects

In this study, we examined origin, destination, and community effects on first- and second-generation immigrants’ health in Europe. We used information from the European Social Surveys (2002–2008) on 19,210 immigrants from 123 countries of origin, living in 31 European countries. Cross-classified multilevel regression analyses reveal that political suppression in the origin country and living in countries with large numbers of immigrant peers have a detrimental influence on immigrants’ health. Originating from predominantly Islamic countries and good average health among natives in the destination country appear to be beneficial. Additionally, the results point toward health selection mechanisms into migration.

Mother's curse neutralizes natural selection against a human genetic disease over three centuries

According to evolutionary theory, mitochondria could be poisoned gifts that mothers transmit to their sons. This is because mutations harmful to males are expected to accumulate in the mitochondrial genome, the so-called 'mother's curse'. However, the contribution of the mother's curse to the mutation load in nature remains largely unknown and hard to predict, because compensatory mechanisms could impede the spread of deleterious mitochondria. Here we provide evidence for the mother's curse in action over 290 years in a human population. We studied a mutation causing Leber's hereditary optical neuropathy, a disease with male-biased prevalence and which has long been suspected to be maintained in populations by the mother's curse. Male carriers showed a low fitness relative to non-carriers and to females, mostly explained by their high rate of infant mortality. Despite poor male fitness, selection analysis predicted a slight (albeit non-significant) increase in frequency, which sharply contrasts with the 35.5% per-generation decrease predicted if mitochondrial DNA transmission had been through males instead of females. Our results are therefore even suggestive of positive selection through the female line that may exacerbate effects of the mother's curse. This study supports a contribution of the mother's curse to the reduction of male lifespan, uncovering a large fitness effect associated with a single mitochondrial variant.

Early-life conditions and adult mortality decline in Dutch cohorts born 1812-1921

Mounting evidence suggests that early-life conditions have an enduring effect on an individual's mortality risks as an adult. The contribution of improvements in early-life conditions to the overall decline in adult mortality, however, remains a debated issue. We provide an estimate of the contribution of improvements in early-life conditions to mortality decline after age 30 in Dutch cohorts born between 1812 and 1921. We used two proxies for early-life conditions: median height and early-childhood mortality. We estimate that improvements in early-life conditions contributed more than five years or about a third to the rise in women's life expectancy at age 30. Improvements in early-life conditions contributed almost three years or more than a quarter to the rise in men's life expectancy at age 30. Height appears to be the more important of the two proxies for early-life conditions.

Early-life disease exposure and associations with adult survival, cause of death, and reproductive success in preindustrial humans

A leading hypothesis proposes that increased human life span since 1850 has resulted from decreased exposure to childhood infections, which has reduced chronic inflammation and later-life mortality rates, particularly from cardiovascular disease, stroke, and cancer. Early-life cohort mortality rate often predicts later-life survival in humans, but such associations could arise from factors other than disease exposure. Additionally, the impact of early-life disease exposure on reproduction remains unknown, and thus previous work ignores a major component of fitness through which selection acts upon life-history strategy. We collected data from seven 18th- and 19th-century Finnish populations experiencing naturally varying mortality and fertility levels. We quantified early-life disease exposure as the detrended child mortality rate from infectious diseases during an individual's first 5 y, controlling for important social factors. We found no support for an association between early-life disease exposure and all-cause mortality risk after age 15 or 50. We also found no link between early-life disease exposure and probability of death specifically from cardiovascular disease, stroke, or cancer. Independent of survival, there was no evidence to support associations between early-life disease exposure and any of several aspects of reproductive performance, including lifetime reproductive success and age at first birth, in either males or females. Our results do not support the prevailing assertion that exposure to infectious diseases in early life has long-lasting associations with later-life all-cause mortality risk or mortality putatively linked to chronic inflammation. Variation in adulthood conditions could therefore be the most likely source of recent increases in adult life span.

An Old Mom Keeps You Young: Mother's Age at Last Birth and Offspring Longevity in Nineteenth-Century Utah

This study analyzes the intergenerational effects of late childbearing on offspring's adult longevity in a population in Utah (United States) that does not display evidence of parity-specific birth control-a so-called natural fertility population. Studies have found that for women who experience late menopause and prolonged reproduction, aging is postponed and longevity is increased. This is believed to indicate female "robustness" and the impact of biological or genetic factors. If indeed there is a genetic component involved, one would expect to also find evidence for the intergenerational transmission of longevity benefits. Our study investigates the relationship between prolonged natural fertility of mothers and their offspring's survival rates in adulthood. Gompertz regression models (N = 7,716) revealed that the offspring of mothers who were naturally fertile until a relatively advanced age lived significantly longer. This observed positive effect of late reproduction was not independent of but conditional upon survival of the mother to the end of her fecundity (defined as age 50). Offspring's relative risks at death beyond age 50 were 6-12 percent lower than those of their counterparts born to mothers who had an average age at last birth. Our results, which account for various early, adult, and later-life conditions, as well as shared frailty, suggest that there is a positive relationship between mother's age at last birth and offspring longevity, and strengthen the notion that age at menopause is a good predictor of this relationship.

Early origins of longevity: prenatal exposures to food shortage among early Utah pioneers

Undernutrition during critical or sensitive prenatal periods may 'program' the fetus for increased chronic disease and mortality in later life. Using birth cohorts that were or were not exposed to severe food shortage in Utah in the mid-19th century, this study examines how in utero exposure to undernutrition is associated with mortality after age 50. The Utah Population Database is used to identify 1392 prenatally exposed individuals and 29,022 individuals from subsequent, unexposed birth cohorts. Gompertz hazards with parametric frailty show that males born between April and June of the famine period (and hence exposed during critical periods in utero during the winter months) have higher mortality risks compared with post-famine cohorts. Alternative Cox non-proportional hazard models suggest that females born during the same period have higher initial mortality risks (starting at age 50) that decline over time creating a mortality crossover with unexposed women at approximately age 70, a result not found for men. An ancillary sibling analysis that uses shared frailty survival models to compare individuals with prenatal exposure to undernutrition to their younger (post-famine) same-sex siblings finds no significant differences in adult mortality for males but the pattern for females support the findings from the previous analysis. Although findings are sensitive to model choice, this study presents evidence that is consistent with an association between undernutrition in utero and adult mortality, shows that effects may be sensitive to the duration and gestational period of exposure, and illustrates the differential exposure effects between genders.

Early life effects across the life course: the impact of individually defined exogenous measures of disease exposure on mortality by sex in 19th- and 20th-century Southern Sweden

Using micro-level longitudinal data from Southern Sweden for 1813 to 1968, this work evaluates the effect of exposure to disease in early life on mortality over the entire life course and separately by sex. The local rates of post-early neonatal mortality are considered indicators of early life disease exposure, and these rates are calculated specifically for each person based on birth date. The loss in median remaining life among exposed individuals who survived to age 1 is 1.1 years for females and 2.1 years for males. Exposed individuals show a cross-over from lower to higher relative mortality as they age. This change occurs in adulthood for males and in old age for females. During adulthood, exposed males present higher rates of death than exposed females. These results are new to the literature and shed light on the importance of adopting a full life course approach and capturing sex differences when evaluating the long-term impacts of early life exposures.

Period-Based Mortality Change: Turning Points in Trends since 1950

We investigate a major turning point in mortality trends at adult ages that occurred for many low‐mortality countries in the late 1960s or early 1970s. We analyze patterns of total and cause‐specific mortality over the past 60 years using data from the Human Mortality Database and the World Health Organization. We focus on four broad categories of causes of death: heart diseases, cerebrovascular diseases, smoking‐related cancers, and all other cancers. We use a two‐slope regression model to assess the timing and magnitude of turning points in mortality trends over this era, making separate analyses by sex, age, and cause of death. The age pattern of temporal changes is given particular attention. Our results demonstrate convincingly that period‐based factors were very significant in the onset of the “cardiovascular revolution” in the years around 1970. In general, although cohort processes cannot be ruled out as a driver of mortality change in recent decades (especially for mortality due to smoking‐related cancers), the evidence reviewed here suggests that period factors have been the dominant force behind the mortality trends of high‐income countries during this era.

Situating mortality: quantifying crisis points and periods of stability

A wide range of stressors can cause a dramatic and sudden rise in the death rate in populations, typically resulting in what is referred to as crisis mortality. Here we present a method to standardize the assessment of identifying moments of crises. A modification of the mortality Z-score methodology which is combined with time series analysis was used to investigate mortality events over the course of nearly two centuries for two populations: Gibraltar and Malta. A benefit of this method is that it situates the yearly death rate within the prevailing mortality pattern, and by doing so allows the researcher to assess the relative impact of that event against the norm for the period under investigation. A series of threshold values were established to develop levels of mortality to distinguish moments of lower mortality than expected, background mortality, a crisis, and a catastrophe. Our findings suggested that within defined periods, a limited number of events constituted moments of excessive mortality in the range of a crisis or higher. These included epidemics (yellow fever and influenza in Gibraltar only, and cholera) and casualties associated with World War II. Episodes of lower than expected mortality were only detected (although not significant) in the 20th century in Malta, and at the micro level, the harvesting effect appears to have occurred following cholera epidemics in both locations and influenza in Gibraltar. The analysis demonstrates clearly that the impact of epidemics can be highly variable across time and populations.

Early life exposure to the 1918 influenza pandemic and old-age mortality by cause of death

OBJECTIVES

We sought to analyze how early exposure to the 1918 influenza pandemic is associated with old-age mortality by cause of death.

METHODS

We analyzed the National Health Interview Survey (n = 81,571; follow-up 1989-2006; 43,808 deaths) and used year and quarter of birth to assess timing of pandemic exposure. We used Cox proportional and Fine-Gray competing hazard models for all-cause and cause-specific mortality, respectively.

RESULTS

Cohorts born during pandemic peaks had excess all-cause mortality attributed to increased noncancer mortality. We found evidence for a trade-off between noncancer and cancer causes: cohorts with high noncancer mortality had low cancer mortality, and vice versa.

CONCLUSIONS

Early disease exposure increases old-age mortality through noncancer causes, which include respiratory and cardiovascular diseases, and may trigger a trade-off in the risk of cancer and noncancer causes. Potential mechanisms include inflammation or apoptosis. The findings contribute to our understanding of the causes of death behind the early disease exposure-later mortality association. The cancer-noncancer trade-off is potentially important for understanding the mechanisms behind these associations.

Phenotype-environment mismatch due to epigenetic inheritance? Programming the offspring's epigenome and the consequences of migration

OBJECTIVE

It has been suggested that epigenetic inheritance is an important factor influencing mortality. We use data about the historical population of Québec (years 1670-1740) to study whether parents modify their offspring's phenotype epigenetically prior to conception in response to predicted/perceived mortality. If so, children growing up in the predicted environment enjoy a phenotype-environment-match that should lower mortality, whereas children growing up in a nonpredicted environment should have a higher mortality.

METHODS

We use the large urban-rural mortality differential to capture the predicted/perceived mortality environment. We categorize children into different groups by their migration status: conceived and living in the same environment (urban or rural); conceived in one but born in another environment (urban-to-rural or rural-to-urban); and born in one but migrating to another environment. We use Kaplan-Meier survival curves and fixed effect survival models to estimate to what extent child survival up to the age of 15 depends on migration status.

RESULTS

Child mortality within families that moved from urban to rural areas does not depend on the child's migration status. Within families that moved to urban areas, children who were conceived and born in the rural areas exhibit the lowest mortality. This contradicts a phenotype-environment-mismatch scenario, which would result in higher rather than lower mortality.

CONCLUSION

We do not find evidence for functional (adaptive) epigenetic inheritance. Migration into an environment with lower or higher extrinsic mortality affects child mortality within the families differently than predicted by the concept of epigenetic inheritance. The results suggest that epigenetic inheritance may not be important for child mortality among migrants.

Are stepparents always evil? Parental death, remarriage, and child survival in demographically saturated Krummhörn (1720-1859) and expanding Québec (1670-1750)

Parental death precipitates a cascade of events leading to more or less detrimental exposures, from the sudden and dramatic interruption of parental care to cohabitation with stepparents and siblings in a recomposed family. This article compares the effect of early parental loss on child survival in the past in the Krummhörn region of East Frisia (Germany) and among the French Canadian settlers of the Saint Lawrence Valley (Québec, Canada). The Krummhörn region was characterized by a saturated habitat, while the opportunities for establishing a new family were virtually unlimited for the French Canadian settlers. Early parental loss had quite different consequences in these dissimilar environments. Event history analyses with time-varying specification of family structure are used on a sample of 7,077 boys and 6,906 girls born between 1720 and 1859 in the Krummhörn region and 31,490 boys and 33,109 girls whose parents married between 1670 and 1750 in Québec. Results indicate that in both populations, parental loss is associated with increased infant and child mortality. Maternal loss has a universal and consistent effect for both sexes, while the impact of paternal loss is less easy to establish and interpret. On the other hand, the effect of the remarriage of the surviving spouse is population-specific: the mother's remarriage has no effect in Krummhörn, while it is beneficial in Québec. In contrast, the father's remarriage in Krummhörn dramatically reduces the survival chances of the children born from his former marriage, while such an effect is not seen for Québec. These population-specific effects appear to be driven by the availability of resources and call into question the universality of the "Cinderella" effect.

Effect of birth season on longevity: thrifty and hopeful phenotypes in historical Quebec

OBJECTIVES

Individuals with fetal growth restrictions may become unhealthy as adult if they live in a nutritionally rich environment. Yet, there is little evidence for the counterpart that profuse resources during early development may prove detrimental in an impoverished adult environment. Using birth season as a proxy for nutrition in utero, this study tests whether early life effects on longevity are conditional on the environment in which people reside during adulthood.

METHODS

I used Cox proportional hazard models of mortality after the age of 60 years among historical cohorts of French Canadian women born before 1750. Models are stratified by siblings to adjust the results for unobserved factors shared by family members.

RESULTS

A birth during winter conferred the best-survival prospects in the south of the Saint-Lawrence River but the worse prospects in the north, where a birth during the fall was associated with the lowest mortality. Women who migrated to live on the other side of the river lost whatever advantage or disadvantage they had from their birth season and faced increases or decreases in risk that were specific to their new location.

CONCLUSIONS

Based on Hales and Barker's thrifty phenotype hypothesis, and adding the "hopeful phenotype" counterpart, this study suggests that cues from the external environment during development are highly specific to that environment and that the slightest change of location may affect the chances for survival into old age. I finally address the role of fertility as a possible mediator or modifier of the effect of birth season on longevity.

Migration and health: a study of effects of early life experiences and current socio-economic situation on mortality of immigrants in Sweden

OBJECTIVES

Previous research has demonstrated mortality differences between immigrants and natives living in Sweden. The aim of this study is to investigate the effects of early life conditions in the country of birth and current socio-economic conditions in adult life in Sweden on cardiovascular, cancer, all other cause and total mortality among immigrants and natives in Sweden.

DESIGN

The cohort data concerning individual demographic characteristics and socio-economic conditions stems from the Swedish Longitudinal Immigrant Database (SLI), a register-based representative database, and consists of individuals from 11 countries of birth, born between 1921 and 1939, who were residents in Sweden between 1980 and 2001. The associations between current socio-economic conditions as well as infant mortality rates (IMR) and Gross Domestic Product (GDP) per capita in the year and country of birth, and total, cardiovascular, cancer and 'all other' mortality in 1980-2001 were calculated by survival analysis using Cox proportional hazards regression to calculate hazard rate ratios.

RESULTS

The effects of current adult life socio-economic conditions in Sweden on mortality are both stronger and more straightforward than the effects of early life conditions in the sense that higher socio-economic status is significantly associated with lower mortality in all groups of diagnoses; however, we find associations between infant mortality rates (IMR) in the year and country of birth, and cancer mortality among men and women in the final model.

CONCLUSIONS

Socioeconomic conditions in Sweden are more strongly associated with mortality than early life indicators IMR and GDP per capita in the year of birth in the country of origin. This finding has health policy and other policy implications.

Conditions de vie durant l’enfance et longévité : évaluation d’une base de données créée à partir du recensement canadien de 1901 et de l’état civil québécois1

Plusieurs études montrent que les conditions de vie vécues dans l’enfance peuvent avoir un effet à long terme sur la santé et la mortalité. Cette niche n’ayant pas été explorée pour la population canadienne, nous avons mis sur pied un projet visant le jumelage du recensement canadien de 1901 et des actes de décès de l’état civil québécois dans le but d’établir l’âge au décès d’enfants pour lesquels il existait des informations socio-économiques. Le but de la présente contribution est de tester la validité des données collectées en les comparant avec des tables de mortalité calculées à l’aide des données issues de la Base de données sur la longévité canadienne (Université de Montréal), et d’examiner des sources de biais potentiels. Parmi les biais potentiels, nous avons évalué la possibilité d’un effet de sélection dans l’échantillon à l’aide d’une régression logistique dans laquelle nous avons introduit plusieurs variables explicatives de la mortalité aux grands âges. Le but recherché étant de savoir si ces variables ont à leur tour un impact sur le fait de trouver ou non un acte de décès.

The relative effects of shocks in early- and later-life conditions on mortality

The relative importance of cohorts' early-life conditions, compared to later period conditions, on adult and old-age mortality is not known. This article studies how cohort-level mortality depends on shocks in cohorts' early- and later-life (period) conditions. I use cohorts' own mortality as a proxy for the early-life conditions, and define shocks as deviations from trend. Using historical data for five European Countries i find that shocks in early-life conditions are only weakly associated with cohorts' later mortality. This may be because individual-level health is robust to early-life conditions, or because at the cohort level scarring, selection, and immunity cancel each other. Shocks in period conditions, measured as deviations from trend in period child mortality, are strongly and positively correlated with mortality at all older ages. The results suggest that at the cohort level changing period conditions drive mortality variation and change.

Reexamining the Dominance of Birth Cohort Effects on Mortality

The association between birth cohort and subsequent mortality has been of interest especially following publication of studies around 1930 of cohorts born up to the latter part of the nineteenth century, particularly for England and Wales. Updated results are presented for this population, together with those for two other cohorts, twentieth-century Japanese and British populations born about 1930, which have been identified as having particularly clear-cut birth cohort patterns, and which are used to underpin incorporation of cohort effects in both British official and actuarial mortality forecasts. Graphical methods used to identify cohort patterns are discussed. A number of limitations and difficulties are identified that mean that the conclusions about the predominance of cohort effects are less robust than often assumed. It is argued that alternative explanations should be considered and that the concentration on birth cohorts with particularly advantaged patterns may distort research priorities.

Is there a trade-off between fertility and longevity? A comparative study of women from three large historical databases accounting for mortality selection

Frontier populations provide exceptional opportunities to test the hypothesis of a trade-off between fertility and longevity. In such populations, mechanisms favoring reproduction usually find fertile ground, and if these mechanisms reduce longevity, demographers should observe higher postreproductive mortality among highly fertile women. We test this hypothesis using complete female reproductive histories from three large demographic databases: the Registre de la population du Québec ancien (Université de Montréal), which covers the first centuries of settlement in Quebec; the BALSAC database (Université du Québec à Chicoutimi), including comprehensive records for the Saguenay-Lac-St-Jean (SLSJ) in Quebec in the nineteenth and twentieth centuries; and the Utah Population Database (University of Utah), including all individuals who experienced a vital event on the Mormon Trail and their descendants. Together, the three samples allow for comparisons over time and space, and represent one of the largest set of natural fertility cohorts used to simultaneously assess reproduction and longevity. Using survival analyses, we found a negative influence of parity and a positive influence of age at last child on postreproductive survival in the three populations, as well as a significant interaction between these two variables. The effect sizes of all these parameters were remarkably similar in the three samples. However, we found little evidence that early fertility affects postreproductive survival. The use of Heckman's procedure assessing the impact of mortality selection during reproductive ages did not appreciably alter these results. We conclude our empirical investigation by discussing the advantages of comparative approaches.