Parental age and offspring mortality: Negative effects of reproductive ageing may be counterbalanced by secular increases in longevity

As parental ages at birth continue to rise, concerns about the effects of fertility postponement on offspring are increasing. Due to reproductive ageing, advanced parental ages have been associated with negative health outcomes for offspring, including decreased longevity. The literature, however, has neglected to examine the potential benefits of being born at a later date. Secular declines in mortality mean that later birth cohorts are living longer. We analyse mortality over ages 30–74 among 1.9 million Swedish men and women born 1938–60, and use a sibling comparison design that accounts for all time-invariant factors shared by the siblings. When incorporating cohort improvements in mortality, we find that those born to older mothers do not suffer any significant mortality disadvantage, and that those born to older fathers have lower mortality. These findings are likely to be explained by secular declines in mortality counterbalancing the negative effects of reproductive ageing.     

Aging in the Context of Cohort Evolution and Mortality Selection

This study examines historical patterns of aging through the perspectives of cohort evolution and mortality selection, where the former emphasizes the correlation across cohorts in the age dependence of mortality rates, and the latter emphasizes cohort change in the acceleration of mortality over the life course. In the analysis of historical cohort mortality data, I find support for both perspectives. The rate of demographic aging, or the rate at which mortality accelerates past age 70, is not fixed across cohorts; rather, it is affected by the extent of mortality selection at young and late ages. This causes later cohorts to have higher rates of demographic aging than earlier cohorts. The rate of biological aging, approximating the rate of the senescence process, significantly declined between the mid- and late-nineteenth century birth cohorts and stabilized afterward. Unlike the rate of demographic aging, the rate of biological aging is not affected by mortality selection earlier in the life course but rather by cross-cohort changes in young-age mortality, which cause lower rates of biological aging in old age among later cohorts. These findings enrich theories of cohort evolution and have implications for the study of limits on the human lifespan and evolution of aging.     

Risk Exposure in Early Life and Mortality at Older Ages: Evidence from Union Army Veterans

This study examines the relation between risk exposures in early life and hazard of mortality among 11,978 Union Army veterans aged 50 and over in 1900. Veterans' risk exposures prior to enlistment—as approximated by birth season, country of birth, residential region, city size, and height at enlistment—significantly influenced their chance of survival after 1900. These effects are robust irrespective of whether socioeconomic well‐being in 1900 has been taken into account; however, they are sensitive to the particular age periods selected for survival analysis. Whereas some of the effects such as being born in Ireland and coming from large cities became apparent in the first decade after 1900 and then dissipated over time, the effects of birth season, being born in Germany, residential region in the United States, and height at enlistment were more salient in the post‐1910 periods. Height at enlistment shows a positive association with risk of mortality in the post‐1910 periods. Compared to corresponding findings from more recent cohorts, the exceptional robustness of the effects of risk exposures prior to enlistment on old‐age mortality among the veterans highlights the harshness of living conditions early in their lives.     

Cohort Reproductive Patterns in Low‐Fertility Countries

This account reports on a project in progress that aims to obtain a comprehensive picture of contemporary fertility levels and trends in 27 low‐fertility countries. Cohort analysis is applied to review the fertility experience of women born from the 1930s through the 1970s. This choice of dates ensures that not only completed fertility but also the fertility patterns of women in the midst of or near the onset of their reproductive period are examined. In most of the 27 countries, completed fertility of successive cohorts has been declining. It appears plausible that the trends discerned in the analysis will continue in the foreseeable future. For these trends to be reversed, women who are about to enter or who are in the midst of their reproductive periods would have to adopt fertility patterns markedly different from those of women born in the 1960s and 1970s.     

Exporting Poor Health: The Irish in England

In the twentieth century, the Irish-born population in England has typically been in worse health than both the native population and the Irish population in Ireland, a reversal of the commonly observed healthy migrant effect. Recent birth cohorts living in England and born in Ireland, however, are healthier than the English population. The substantial Irish migrant health penalty arises principally for cohorts born between 1920 and 1960. In this article, we attempt to understand the processes that generated these changing migrant health patterns for Irish migrants to England. Our results suggest a strong role for economic selection in driving the dynamics of health differences between Irish-born migrants and white English populations.     

Fertility decline in a US population favoring large families: A hazard-model analysis of the effect of sib death on Amish fertility

This paper uses proportional hazards techniques and population data from a directory of the Old Order Amish of the Lancaster, PA settlement. It examines the effect of death of the immediately prior sibling on the risk of childbearing for up to 11 children. Prior research typically has pooled data for maternal cohorts. In contrast, separate models are estimated for each maternal cohort. The results are based on all reported first marriages of Amish women born between 1884–1973 (N = 4066). Hazard models run separately for children of each birth order reveal that net of maternal age and length of the prior birth interval (and other statistical and design controls), the death of the prior sib significantly increases the risk of a subsequent birth for the lower birth orders. Separate models by maternal cohort show that sib death increases the risk primarily for later cohorts. The pattern of effects from child mortality and other variables suggests changes in fertility behavior among the Amish, who have strong, traditional norms opposing contraception and favoring large families.     

Migration and Intergenerational Replacement in Europe

There are long‐standing concerns over low fertility levels in Europe and an increasingly important debate on the extent to which migration can compensate for below‐replacement fertility. To inform this debate, a wide array of indicators have been developed to assess the joint influence of fertility, mortality, and migration on birth replacement and intergenerational replacement. These indicators are based on various models and assumptions and some are particularly data demanding. In this article we propose a simple method to assess how far migration alters the extent of replacement for a birth cohort as it ages. We term the measure the overall replacement ratio (ORR). It is calculated by taking the size of a female birth cohort at selected ages divided by the average size of the cohorts of mothers in the year of birth. We present estimates of the ORR for a range of European countries representing different replacement regimes. We demonstrate that for many countries net migration has become a key factor in their population trends during the last few decades.     

Long-term mortality patterns in Chinese history: evidence from a recorded clan population

Human populations have lived on the earth for millions of years, yet the study of population history only began to be established in the mid-twentieth century. In spite of the considerable progress in the study of historical demography which has since been made, there have been hardly any detailed studies of fertility and mortality before the sixteenth century. This study, by analysing a set of Chinese genealogies, examines long-term mortality patterns in a selected clan population over a period of more than 1000 years. The result shows that, in this selected population, mortality fluctuated around a relatively high level and showed no secular change over the very long period studied. The study also provides a comparison between the mortality patterns found in the selected population and those observed in a much larger Chinese lineage population, as well as those recorded among the British elites born between the sixteenth and the early nineteenth century. Based on the findings of this research, the paper presents some tentative suggestions about long-term mortality changes in Chinese history.     

Steep increase in best-practice cohort life expectancy

We analyze trends in best-practice life expectancy among female cohorts born from 1870 to 1950. Cohorts experience declining rather than constant death rates, and cohort life expectancy usually exceeds period life expectancy. Unobserved mortality rates in non-extinct cohorts are estimated using the Lee-Carter model for mortality in 1960–2008. Best-practice cohort and period life expectancies increased nearly linearly. Across cohorts born from 1870 to 1920 the annual increase in cohort length of life was 0.43 years. Across calendar years from 1870 to 2008, the annual increase was 0.28 years. Cohort life expectancy increased from 53.7 years in the 1870 cohort to 83.8 years in the 1950 cohort. The corresponding cohort/period longevity gap increased from 1.2 to 10.3 years. Among younger cohorts, survival to advanced ages is substantially higher than could have been anticipated by period mortality regimes when these cohorts were young or middle-aged. A large proportion of the additional expected years of life are being lived at ages 65 and older. This substantially changes the balance between the stages of the life cycle.     

Demographic Transitions and Changes in the Living Arrangements of Children: The Netherlands 1850–2010

The transformation of Europe’s demographic regime over the past two centuries has led to considerable changes in the living arrangements of children. We study long-term changes, making use of three datasets covering the living arrangements of children born between 1850 and 1993 in the Netherlands: a historical national sample of children born between 1850 and 1922, a retrospective survey covering children born between 1923 and 1985, and data from the national population registry relating to children born between 1986 and 1993. We describe the changes in terms of whether fathers, mothers, and stepparents lived with these children at birth and at age 15. We observe a massive increase in the percentage of children growing up in a complete family between the 1850–1879 cohort and the mid-twentieth century cohorts and a return to nineteenth-century conditions in the most recent birth cohort. Time spent in a complete family increased continuously from the mid-nineteenth century on, to decrease again from the 1960s on.     

Changes in the age dependence of mortality and disability: Cohort and other determinants

Though the general trend in the United States has been toward increasing life expectancy both at birth and at age 65, the temporal rate of change in life expectancy since 1900 has been variable and often restricted to specific population groups. There have been periods during which the age- and gender-specific risks of particular causes of death have either increased or decreased. These periods partly reflect the persistent effects of population health factors on specific birth cohorts. It is important to understand the ebbs and flows of cause-specific mortality rates because general life expectancy trends are the product of interactions of multiple dynamic period and cohort factors. Consequently, we first review factors potentially affecting cohort health back to 1880 and explore how that history might affect the current and future cohort mortality risks of major chronic diseases. We then examine how those factors affect the age-specific linkage of disability and mortality in three sets of birth cohorts assessed using the 1982, 1984, and 1989 National Long Term Care Surveys and Medicare mortality data collected from 1982 to 1991. We find large changes in both mortality and disability in those cohorts. providing insights into what changes might have occurred and into what future changes might be expected.     

性别视角下的迁移历程研究——基于中国1930～1969年出生队列的分析

利用2014年中国健康与养老追踪调查生命历程数据,探究中国1930～1969年出生队列的迁移历程及其性别差异,运用事件史分析方法解释重要生命事件(教育、就业、婚姻、生育)对男性和女性迁移历程的影响。研究结果表明,不同出生年代人口的迁移历程呈现明显的队列差异和性别差异;与1940～1949年和1950～1959年出生队列相比,1930～1939年和1960～1969年出生队列在迁移高峰年龄(20～24岁)时的政策限制较少而终身累计迁移频率更高,性别差异也更显著;教育和非农就业转移会促进终身迁移机会,较早结婚和较多生育的作用则相反;非农就业转移对女性的多次迁移有更明显的促进作用,会缩小男女之间的迁移差距;结婚和生育会降低迁移概率,而离婚会增加迁移概率,这些事件对女性的影响更大。     

Reconstructing the size of the African American population by age and sex, 1930–1990

We estimate the size of the African American population in five-year age groups at census dates from 1930 to 1990 using a three-part strategy. For cohorts born after 1935, we follow the U.S. Census Bureau in using classical demographic analysis. To estimate the size of cohorts born before 1895, we use extinct-generation estimates. For remaining cohorts, we implement an age/period/cohort model of census counts. All approaches are applied to a data set in which the age distribution of deaths has been corrected for age misreporting. Results provide strong confirmation of the basic validity of Census Bureau estimates of census undercounts for African Americans while extending estimates to new cohorts and periods. Our estimates are less consistent with an historical series prepared by Coale and Rives (1973).     

Competing Demands from Aging Parents and Adult Children in Two Cohorts of American Women

In late middle age, individuals may face competing demands on their time and financial resources from elderly parents and young adult children. This study uses the Panel Study of Income Dynamics to examine changes over time in the probability of having children and living parents for women aged 45 to 64. We compare two cohorts: those born in the 1920s and 1930s and those born in the 1940s and 1950s. We find that there has been a dramatic increase in the probability of having children and living parents and that this increase has been driven mainly by changes in life expectancy of the parent generation. We further examine transfers of money and co‐residence for women in the later cohort. We find that while women may not give to parents and children concurrently, approximately 30 percent of them have provided support to both parents and children at some point in the past.     

Intergenerational Transmission of Age at First Birth in the United States: Evidence from Multiple Surveys

It is well established that the timing of childbearing is transmitted from parents to children in the United States. However, little is known about how the intergenerational link has changed over time and under structural and ideological transformations associated with fertility behaviors. This study first considers changes across two birth cohorts from the National Longitudinal Survey of Youth (NLSY) in the extent to which parents’ age at first birth is transmitted to their children. The first cohort includes individuals born during the late 1950s through the early 1960s (NLSY79), while the second includes individuals born in the early 1980s (NLSY97). Results from discrete-time event history analyses indicate that the intergenerational transmission of age at first birth significantly increased for both daughters and sons. These results were confirmed by analyses of data from three cycles of the National Survey of Family Growth spanning the same time period. Over this period, age at first childbirth became increasingly younger for children born to teenage mothers and increasingly older for those born to mothers who began parenthood after age 25. These patterns have important implications for the reproductive polarization hypothesis.     

Fertility patterns among religious groups in Canada

The U shape that has been traced out by the crude birth rate in the United States and Canada is well known. Falling birth rates reached a low point in the mid-1930’s; the rate rose to a peak in 1947 and remained high through the 1950’s. In terms of cohorts, completed family size was smallest for women born around 1910, whose childbearing was concentrated in the 1930’s. With data from the 1961 census of Canada, trends in cohort marital fertility by religion are examined. The U pattern appears for both Protestants and Jews. For Catholics, a reversal in the downward trend of family size had not appeared by 1961, although the U pattern can be discerned for some subgroups such as Catholics living in big cities and persons of Irish ancestry. In the United States, however, changes in family size for all three religious groups and both whites and nonwhites follow the U pattern. Religious differentials in family size in Canada have been decreasing, but they remain much larger than either religious or color differentials in the United States, which show no decrease. The distinctive features of Catholic fertility in Canada are most pronounced among the regionallyconcentrated French Canadians, suggesting an interplay of religious, regional, and ethnic influences.     

Five decades of missing females in China

This paper seeks to explain the dearth of females in the population of China in cohorts born from the late 1930s to the present. We demonstrate that in virtually all cohorts. the shortage of females in comparison with males is revealed when the cohort is first enumerated in a census. Subsequently it barely changes, an indication that female losses occur very early in life. Using the high-quality data from the censuses and fertility surveys in China, we show that many of the births of the girls missing in the censuses were not reported in the surveys because they died very young. The incidence of excess early female mortality (probably infanticide) declined precipitously in the Communist period, but not to zero. The recent escalation in the proportion of young females missing in China has been caused largely by rapidly escalating sex-selective abortion.     

An analysis of the change of marriage pattern of Beijing women]

Changes in marriage patterns occur primarily in changes in the age at marriage. During a study of fertility among Beijing, China, women in 1981, another study was undertaken of the marriage situation of 8299 women who were born in 1914, 1920, 1930, 1940, and 1946. Data show that the rate of unmarried women was close to zero, which is one reason for the high birth rate in the past. A majority of the urban and rural women born in 1914, 1920, and 1930 married before the age of 15 years, indicating that the economic, social, and marriage customs for those decades changed very little. The 1940 cohort, however, showed no urban marriages prior to the age of 15 years and less than 1% in the villages, the reason being that these women were of marriageable age in the mid-to-late 1950s when China underwent major social and economic changes that raised the status of women and permitted them to join the work force or go to school. Very few urban women in the 1946 cohort married before 20 years of age, and the number of rural women who married before they were 18 years old declined noticeably. Findings also show that for both urban and rural women, the average age at marriage was 1-3 years later than the modal age at marriage. Beginning with the 1940 cohort the age at marriage was older by 2 1/2 years, signaling major changes. Except for the 1914 cohort, the median age at marriage for all others gradually became higher. 70% of the 1946 cohort voluntarily married after turning 23 years old, reflecting the effectiveness of the late marriage, late birth policy. Although close to 59% of rural women born in 1946 married before 23 years of age, nearly double the rate for urban women, it is nevertheless a major change from the 1930 cohort where 95% of the women married before turning 23 years old.     

Economic Conditions in Early Life and Circulatory Disease Mortality

I test the Developmental Origins of Health and Disease hypothesis using a cohort perspective on mortality. I combine data from the National Health Interview Survey Linked Mortality Files, 1986–2006, and U.S. economic data between 1902 and 1956 (403,746 respondents and 39,439 deaths), to estimate how exposures to adverse economic conditions in utero and during the first three years of life affect circulatory disease mortality risk in adulthood. I also examine cohort‐based variation in these associations. Findings suggest that in utero exposures to poor economic conditions increased risk of death from circulatory diseases. Results are consistent with theory and evidence suggesting that developmental processes early in life are strongly associated with circulatory disease susceptibility in older adulthood. However, findings indicate that the mortality effects of these early‐life exposures have likely weakened across birth cohorts.     

Education and survival: Birth cohort,period, and age effects

Previous studies have found that educational differences in mortality are weaker among the elderly. In this study I examine whether either cohort or period effects may have influenced the interpretation of age effects. Six 10-year birth cohorts are followed over 30 years through decennial censuses. Differential survival is inferred from changes in the relative proportions of a cohort in each education category as the cohort ages. In cross-section, younger persons generally show stronger education effects on survival, although this pattern is clearer for women than for men. There is evidence of period effects. Within cohorts, relative survival tends to increase with age.