Age reporting among white Americans aged 85+: Results of a record linkage study

This study investigates age reporting on the death certificates of older white Americans. We link a sample of death certificates for native-born whites aged 85+ in 1985 to Social Security Administration records and to records of the U.S. censuses of 1900, 1910, and 1920. When ages in these sources are compared, inconsistencies are found to be minimal, even beyond age 95. Results show little distortion and no systematic biases in the reported age distribution of deaths. To explore the effect of age misreporting on old-age mortality, we estimate "corrected" age-specific death rates by the extinct-generation method for the U.S. white cohort born in 1885. With few exceptions, corrected and uncorrected rates in single years differ by less than 3% and are not systematically biased. When we compare corrected rates with those for the same birth cohort in France, Japan, and Sweden, we find that white American mortality at older ages is exceptionally low.     

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.     

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.     

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.     

Childbearing and Women's Survival: New Evidence from Rural Bangladesh

Effects of childbearing on women's mortality and the implications of family planning programs in reducing these effects are examined in a 20‐year prospective study of more than 2,000 women in Matlab, Bangladesh. Maternal mortality is defined as a death occurring in the six weeks after childbirth. But childbearing may affect women's survival beyond this brief period. Additional hypotheses considered relate to 1) cumulative exposure to childbearing, whether measured by parity or pace of childbearing, 2) age at first birth, and 3) effects beyond the reproductive ages. The results offer no support to cumulative exposure hypotheses, showing no link between parity or pace of childbearing and mortality risk. Instead, we identify an extended period of heightened mortality risk associated with each birth—the year of the birth and the two subsequent years. Family planning programs, by reducing the number of children and therefore a woman's exposure to extended maternal mortality risk, potentially increase survival. Research is needed to identify and address the specific causes of extended maternal mortality risk so that appropriate ameliorative programs may be developed.     

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.     

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.     

Maternal Age and Child Development

Although the consequences of teen births for both mothers and children have been studied for decades, few studies have taken a broader look at the potential payoffs—and drawbacks—of being born to older mothers. A broader examination is important given the growing gap in maternal ages at birth for children born to mothers with low and high socioeconomic status. Drawing data from the Children of the NLSY79, our examination of this topic distinguishes between the value for children of being born to a mother who delayed her first birth and the value of the additional years between her first birth and the birth of the child whose achievements and behaviors at ages 10–13 are under study. We find that each year the mother delays a first birth is associated with a 0.02 to 0.04 standard deviation increase in school achievement and a similar-sized reduction in behavior problems. Coefficients are generally as large for additional years between the first and given birth. Results are fairly robust to the inclusion of cousin and sibling fixed effects, which attempt to address some omitted variable concerns. Our mediational analyses show that the primary pathway by which delaying first births benefits children is by enabling mothers to complete more years of schooling.     

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.     

Fertility trends in Australia

Using published data from the Australian vital registration and census systems, several time series are compiled: crude birth rates from the 1860s; fertility rates from the 1880s; age-specific and parity-specific measures from the 191Os; cumulative fertility measures by birth year of parent beginning with the 1890s; and cumulative fertility measures for marriages by year contracted from the 1910s.The decline in fertility to the 1930s, the upswing to 1961, and declines thereafter revealed by annual fertility measures show far more variation than do measures of total generation fertility—2.7 children per woman born in 1893–95, 2.3 1906–10, 2.8 1921–25, and perhaps 3.0 for women born in the 1930s. Both annual and generation measures show a younger age at parenthood, a decrease in childlessness, and progressively fewer large families. In the light of present experience, it seems not unreasonable to project generation fertility of 2.5 children, implying a crude birth rate of about 20 per thousand for the next fifteen years or so.     

Some comments on Ursula M. Cowgill's article, 'life and death in the sixteenth century in the city of York' (Population Studies, July 1967)

Abstract The initial purpose of Miss Cowgill's investigation was to study possible differences in mortality according to the season of birth, a study in which groups of people must be followed from birth to death. In the present case the groups were composed of people born in six parishes of the City of York between 1538 and 1601.     

Is Fertility Behavior in Our Genes? Findings from a Danish Twin Study

This article investigates the fertility of Danish twins born during the periods 1870–1910 and 1953–64 in order to pursue two central questions for understanding human reproduction: Do genetic dispositions influence fertility and fertility-related behavior? Does the relevance of the “nature versus nurture” debate shift over time or with demographic regimes? The authors find that genetic influences on fertility exist, but that their relative magnitude and pattern are contingent on gender and on the socioeconomic environment experienced by cohorts. Among females born in 1880–90 and after 1955, about 30–50 percent of the variance in fertility is due to genetic influences; these influences are substantially smaller for earlier and for interim birth cohorts. Male fertility is generally subject to smaller genetic and larger shared-environment effects than female fertility. Because genetic effects are most prevalent in situations with deliberately controlled fertility and relatively egalitarian socioeconomic opportunities, the authors propose that the genetic dispositions affect primarily fertility behavior and motivations for having children. Analyses of fertility motivations, measured by age of first attempt to have a child, support this interpretation.     

Residential Mobility Across Local Areas in the United States and the Geographic Distribution of the Healthy Population

Determining whether population dynamics provide competing explanations to place effects for observed geographic patterns of population health is critical for understanding health inequality. We focus on the working-age population—the period of adulthood when health disparities are greatest—and analyze detailed data on residential mobility collected for the first time in the 2000 U.S. census. Residential mobility over a five-year period is frequent and selective, with some variation by race and gender. Even so, we found little evidence that mobility biases cross-sectional snapshots of local population health. Areas undergoing large or rapid population growth or decline may be exceptions. Overall, place of residence is an important health indicator; yet, the frequency of residential mobility raises questions of interpretation from etiological or policy perspectives, complicating simple understandings that residential exposures alone explain the association between place and health. Psychosocial stressors related to contingencies of social identity associated with being black, urban, or poor in the United States may also have adverse health impacts that track with structural location even with movement across residential areas.     

Birth spacing and child mortality in bangladesh and the Philippines

This analysis uses data from Bangladesh and the Philippines to demonstrate that children who are born within 15 months of a preceding birth are 60 to 80% more likely than other children to die in the first two years of life, once the confounding effects of prematurity are removed. The risks associated with short conception intervals are confined to children who are also high birth order; they persist in the presence of controls for prior familial child mortality, breast-feeding, mother's age, and socioeconomic status. In Bangladesh but not in the Philippines, these effects are confined to the neonatal period.     

Does Late Reproduction Extend the Life Span? Findings from European Royalty

Statistical associations between late reproduction and female longevity led to speculations that a late birth increases a mother's life span. The database used here includes all descendants of King George I of England (1660–1727) and his wife, Sophie Dorothea (1666–1726), born in the royal dynasties in Europe up to 1939 (n=1,672). In the era of British world supremacy, these descendants formed the uppermost layer of the European aristocracy, occupying all royal thrones from 1850 onward. Novel in this study is the use of pedigree information. In pairs of ever‐married full sisters (brothers), both surviving to 45 (50) years, both having at least one child, the study examines whether the sibling with the first—or last—child born later in life also lived a longer life. This design controls for genetics, socioeconomic status, parity, social support, child mortality, birth cohort, and various environmental factors. In the 157 pairs of sisters and 191 pairs of brothers, later reproduction did not extend the life span.     

A new method for estimating the level of natural fertility in populations practicing birth control

The natural fertility schedule of a population is the schedule of age-specific marital fertility we would observe if no birth control were being practiced. In natural fertility (no birth control) populations we can observe the natural fertility schedule directly, but in populations practicing birth control the natural fertility schedule is disguised by the marital fertility rates in those age intervals in which control is exercised, the marital fertility rates being below the natural rates. This paper elaborates a method for estimating the natural fertility schedules of populations practicing birth control. Two alternative models are presented, one nonlinear and one linear. The use of these models is then illustrated with reference to the Old Order Amish population of Lancaster County, Pennsylvania. It is shown that for Amish women born between 1860 and 1900 both the nonlinear and linear models yield an estimate of .843 as the ratio between Amish and Hutterite natural fertility schedules.     

The Intergenerational Effect of Cambodia's Genocide on Children's Education and Health

We investigate the intergenerational impact of conflict on the educational and health outcomes of children born years after the conflict ended by exploiting geographical variation in the intensity of the genocide that occurred during the Khmer Rouge (KR) regime in Cambodia. We find that children of individuals who were of prime marriage age during the genocide and experienced greater intensity of genocide have worse educational and health outcomes. In particular, for each standard deviation increase in the intensity of the genocide, average children's normal grade progression rate decreases by 0.03 standard deviations and average children's height‐for‐ age Z‐score decreases by 0.06 standard deviations. We examine several channels through which genocide could affect children born to survivors after the conflict and find suggestive evidence that the marriage market acts as a channel that transmits the adverse impact of conflict across generations. Our findings are robust to alternative measures of mortality rates and post‐KR internal migration.     

Falling Short of Highest Life Expectancy: How Many Americans Might Have Been Alive in the Twentieth Century?

Life expectancy at birth in the United States during the twentieth century was lower than in many other highly developed countries. We investigate how this mortality disadvantage in the last 100 years translates into the number of hypothetical lives lost and their sex and age structure. We estimate the hypothetical US population if it had experienced in each decade since 1900 the mortality level of the country with the then highest life expectancy and compare the results to the actual figures in 2000. By 2000, the number of additional people who could have been alive had the mortality levels in the United States been as low as those in countries with the highest life expectancy was 66 million. This number is distributed equally between males and females. Suboptimal mortality at reproductive ages is crucial for the cumulative effect of potential lives lost, resulting from premature deaths of women who could still become first‐time mothers or bear additional children. Out of the 66 million additional persons who could have been alive in 2000, 45 million are attributable to those indirect deaths. Although the differences in the composition of the population by sex and age under the two mortality regimes are minor, the majority of people who might have been alive—54 million—were of working age or younger.     

How Has the Lower Boundary of Human Mortality Evolved,and Has It Already Stopped Decreasing?

In contrast to the upper boundary of mortality, the lower boundary has so far largely been neglected. Based on the three key features—location, sex-specific difference, and level—I analyze past and present trends in the lower boundary of human mortality. The analysis is based on cohort mortality data for 38 countries, covering all the cohorts born between 1900 and 1993. Minimum mortality is analyzed using observed as well as smoothed estimates. The results show that the ages at which minimum mortality is reached have shifted to lower ages. Although the differences have become almost negligible over time, males are showing higher levels of minimum mortality than females. The level of minimum mortality was halved more than five times over the analyzed time horizon. The results also suggest that even after more than 150 years of mortality improvements, minimum mortality has not yet reached a lowest limit and is likely to decrease further in the near future. Trends in the three key features also raise questions about the importance of evolutionary, social, and biological determinants for the recent and future development of minimum mortality.