The Phoenix population: demographic crisis and rebound in Cambodia

Did the 1918 influenza pandemic cause a 1920 baby boom? Demographic evidence from neutral Europe

In 1919-20, the European countries that were neutral in the First World War saw a small baby bust followed by a small baby boom. The sparse literature on this topic attributes the 1919 bust to individuals postponing conceptions during the peak of the 1918-20 influenza pandemic and the 1920 boom to recuperation of those conceptions. Using data from six large neutral countries of Europe, we present novel evidence contradicting that narrative. In fact, the subnational populations and maternal birth cohorts whose fertility was initially hit hardest by the pandemic were still experiencing below-average fertility in 1920. Demographic evidence, economic evidence, and a review of post-pandemic fertility trends outside Europe suggest that the 1920 baby boom in neutral Europe was caused by the end of the First World War, not by the end of the pandemic.

Contemporary Marriage in Cambodia

Previous work has suggested that the drastic Khmer-Rouge-era changes to the family institution have not endured. Potentially more influential in the long term were the rapid socio-economic changes Cambodia underwent starting in the 1990s. We use four waves of the Cambodian Demographic and Health Surveys from 2000 to 2014 to document contemporary trends in marriage formation and dissolution. We find little change in the centrality of marriage, as both cohabitation and sex between unmarried partners remain quite rare. Marriage also continues to be nearly universal and early for women, but we find that the transition to self-arranged "love" marriages occurred earlier and faster than previously documented. A sign that parental endorsement may still matter though, marriage dissolution continues to be associated with spousal characteristics deemed undesirable by past generations. While higher among recent marriage cohorts, especially in the first year after marriage, levels of marriage dissolution remain comparatively low overall.

From the Ground Up: A Multidisciplinary Approach to Past Fertility and Population Narratives

Population dynamics form a crucial component of human narratives in the past. Population responses and adaptations not only tell us about the human past but also offer insights into the present and future. Though an area of substantial interest, it is also one of often limited evidence. As such, traditional techniques from demography and anthropology must be adapted considerably to accommodate the available archaeological and ethnohistoric data and an appropriate inferential framework must be applied. In this article, I propose a ground-up, multidisciplinary approach to the study of past population dynamics. Specifically, I develop an empirically informed path diagram based on modern fertility interactions and sources of past environmental, sociocultural, and biological evidence to guide high-resolution case studies. The proposed approach is dynamic and can evolve in response to data inputs as case studies are undertaken. In application, this approach will create new knowledge of past population processes which can greatly enhance our presently limited knowledge of high-frequency, small-scale demographic fluctuations, as well as contribute to our broader understanding of significant population disturbances and change throughout human history.

The Demographic Drivers of Grief and Memory After Genocide in Guatemala

Mortality crises are relatively common demographic events, but we know little about how they affect local populations beyond excess mortality. I argue that using a kinship perspective to study mortality crises provides valuable insights into (1) how excess mortality affects the exposure to kin loss and (2) how family bereavement may contribute to the reproduction of historical memory in the long term. I explore these two processes using a unique genealogical database that records the complete demographic history of Rio Negro, a genocide-affected population in Guatemala, between 1982 and 2015. The analysis shows that deaths from the 1982 genocide were balanced by age, sex, and socioeconomic status. One third of the population were killed, but two thirds were left bereaved (the top 10% most affected individuals lost 30% of their nuclear family relatives and 23% of their extended family relatives). Notably, the proportion of the population related to a victim did not change between 1983 and 2015. The persistence of family bereavement can be interpreted as a prolongation of grief or as a driver of historical memory. These demographic dynamics have implications for the study of historical events beyond mortality crises.

Life After Loss: A Prospective Analysis of Mortality Exposure and Unintended Fertility

The relationship between mortality and fertility is a key component of demographic transition theory, placing it at the center of extensive inquiry. Among other linkages, mortality in women's communities and social networks influences their subsequent fertility. Existing demographic research assumes this is principally due to volitional mechanisms, implying that exposure to mortality consolidates women's desire to become pregnant, leading to intended fertility. Yet, insights from other disciplines suggest that mortality exposure could also increase women's unintended fertility through psychological, relational, and behavioral mechanisms. This study examines the relationships between network mortality exposure and women's hazard of pregnancy, and of unintended pregnancy specifically. We analyze two years (2009-2011) of closely spaced panel data on young Malawian women (N=1,272) enrolled in the Tsogolo la Thanzi study. Our data include information on funeral attendance and fertility desires measured weeks before conception, which is confirmed through frequent pregnancy testing. Hazard models show that the number of funerals women attend corresponds with a higher hazard of pregnancy and of unintended pregnancy specifically. These findings make clear that mortality exposure can influence fertility not by shaping women's desires but by disrupting the realization of those desires.

How Nearby Homicides Affect Young Women's Pregnancy Desires: Evidence From a Quasi-Experiment

Leveraging spatiotemporal variation in homicides that occurred during a 2.5-year weekly panel survey of 387 women ages 18-22 in Flint, Michigan, we investigate how young women's desires to become pregnant and to avoid pregnancy evolve in response to local homicides during the transition to adulthood. To address the endogeneity of exposure, we explore how the same woman's pregnancy desires (1) differed, on average, across weeks before and after the first homicide occurred within a quarter mile of her home; (2) evolved in the aftermath of this initial homicide exposure; and (3) changed in response to additional nearby homicides. One-fifth (22%) of women were exposed to a nearby homicide at least once during the study, and one-third of these women were exposed multiple times. Overall, the effects of nearby homicides were gradual: although average desires to become pregnant and to avoid pregnancy differed after initial exposure, these differences emerged approximately three to five months post-exposure. Repeated exposure to nearby homicides had nonlinear effects on how much women wanted to become pregnant and how much they wanted to avoid pregnancy. Together, our analyses provide a new explanation for why some young women-especially those who are socially disadvantaged-desire pregnancy at an early age.

Brazil's Missing Infants: Zika Risk Changes Reproductive Behavior

Zika virus epidemics have potential large-scale population effects. Controlled studies of mice and nonhuman primates indicate that Zika affects fecundity, raising concerns about miscarriage in human populations. In regions of Brazil, Zika risk peaked months before residents learned about the epidemic and its relation to congenital anomalies. This spatiotemporal variation supports analysis of both biological effects of Zika infection on fertility and the effects of learning about Zika risk on reproductive behavior. Causal inference techniques used with vital statistics indicate that the epidemic caused reductions in birth cohort size of approximately one-quarter 18 months after Zika infection risk peaked but 10 months after public health messages advocated childbearing delay. The evidence is consistent with small but not statistically detectable biological reductions in fecundity, as well as large strategic changes in reproductive behavior to temporally align childbearing with reduced risk to infant health. The behavioral effects are larger for more-educated and older women, which may reflect facilitated access to information and to family planning services within high-risk, mosquito-infested urban locations as well as perceptions about the opportunity costs of risks to pregnancy and infant survival.

Maternal cumulative prevalence measures of child mortality show heavy burden in sub-Saharan Africa

We advance a set of population-level indicators that quantify the prevalence of mothers who have ever experienced an infant, under 5-y-old child, or any-age child die. The maternal cumulative prevalence of infant mortality (mIM), the maternal cumulative prevalence of under 5 mortality (mU5M), and the maternal cumulative prevalence of offspring mortality (mOM) bring theoretical and practical value to a variety of disciplines. Here we introduce maternal cumulative prevalence measures of mortality for multiple age groups of mothers in 20 sub-Saharan African countries with Demographic and Health Surveys data spanning more than two decades. The exercise demonstrates the persistently high prevalence of African mothers who have ever experienced a child die. In some African countries, more than one-half of 45- to 49-y-old mothers have experienced the death of a child under age 5, and nearly two-thirds have experienced the death of any child, irrespective of age. Fewer young mothers have experienced a child die, yet in many countries, up to one-third have. Our results show that the mIM and mU5M can follow distinct trajectories from the infant mortality rate (IMR) and under 5 mortality rate (U5MR), offering an experiential view of mortality decline that annualized measures conceal. These measures can be adapted to quantify the prevalence of recurrent offspring mortality (mROM) and calculated for subgroups to identify within-country inequality in the mortality burden. These indicators can be used to improve current understandings of mortality change, bereavement as a public health threat, and population dynamics.

The Effects of Conflict on Fertility: Evidence From the Genocide in Rwanda

Our study analyzes the fertility effects of the 1994 genocide in Rwanda. We study the effects of violence on both the duration time to the first birth in the early post-genocide period and on the total number of post-genocide births per woman up to 15 years following the conflict. We use individual-level data from Demographic and Health Surveys, estimating survival and count data models. This article contributes to the literature on the demographic effects of violent conflict by testing two channels through which conflict influences fertility: (1) the type of violence exposure as measured by the death of a child or sibling, and (2) the conflict-induced change in local demographic conditions as captured by the change in the district-level sex ratio. Results indicate the genocide had heterogeneous effects on fertility, depending on the type of violence experienced by the woman, her age cohort, parity, and the time horizon (5, 10, and 15 years after the genocide). There is strong evidence of a child replacement effect. Having experienced the death of a child during the genocide increases both the hazard of having a child in the five years following the genocide and the total number of post-genocide births. Experiencing sibling death during the genocide significantly lowers post-genocide fertility in both the short-run and the long-run. Finally, a reduction in the local sex ratio negatively impacts the hazard of having a child in the five years following the genocide, especially for older women.

Design and measurement in a study of war exposure, health, and aging: protocol for the Vietnam health and aging study

BACKGROUND

Survivors of war throughout the world experience illnesses and injuries that are crucial to understand, given the ongoing treatment and adaptation they demand. In developing countries like Vietnam, where population aging and chronic disease burdens are rapidly rising, aging populations have seen a disproportionate share of armed conflict and related casualties. This paper describes the Vietnam Health and Aging Study (VHAS), a unique resource for investigating mechanisms of association between diverse exposures to armed conflict during the Vietnam War and multiple dimensions of older adult health among survivors of that war.

METHODS

The VHAS utilizes a longitudinal design, the first wave of data collection conducted in 2018 among 2447 older adults. A second wave of follow-up data collection, scheduled to take place in 2021, will examine life course, social relational and health and mortality transitions. The VHAS was conducted in four northern Vietnamese districts purposively selected to represent a spectrum of war exposure as indicated by intensity of bombings. Additionally, VHAS uses random sampling within gender and military service subdomains to permit unique gender-specific analyses of military service, trauma exposure and health. The VHAS' face-to-face interviews include modules detailing war and military service experiences; warzone stressors; and multiple dimensions of health such as chronic disease, functional limitation, disability, health behaviors, cognition and psychological health. Biomarker data collected for the full VHAS sample includes anthropometric and functional tests such as grip strength and blood pressure, hair samples for cortisol assay, and capillary blood samples to assay C-reactive protein, cholesterol, HbA1c, and other markers of interest for cardiovascular and other disease risks and for testing the impact of early life stressors on later life health. Blood samples will also permit epigenetic analysis of biological aging.

DISCUSSION

Future VHAS investigations will examine dynamic linkages between war exposure, mortality and morbidity, while taking into account the selective nature of each of these processes. Longitudinal analyses will examine late-life health transitions and war-related resiliency.

Fear of violence during armed conflict: Social roles and responsibilities as determinants of fear

This article investigates the prevalence and determinants of fear as a consequence of living through armed conflict. We use survey data from Nepal during the armed conflict (1996-2006) to examine how trauma, sex and gender, age, marriage, and household size affect fear of violence. We also disaggregate types of worry, and find substantial variance on whether respondents were more concerned about livelihood consequences of conflict than physical danger. We supplement quantitative analyses with discussion of in-depth interviews from the study area on these same topics. Overall, our results highlight the enduring impact of gender roles in Nepal and that conflict might disproportionately affect those who are already vulnerable and have greater social responsibilities. This article provides a unique comparison between fear of violence during armed conflict in a low-income country to the fear of crime literature based in high-income countries.

Death Is Not the End: A Register-Based Study of the Effect of Parental Death on Adult Children's Childbearing Behavior in Sweden

Macro-level studies have shown that rapid increases in mortality can affect fertility rates. Parental death has also been linked to negative psychological and physical outcomes, reduced relationship quality, and making bereaved children attach more importance to their families. No prior study has examined whether parental death influences adult children's fertility at the microlevel. This study applies event history techniques to Swedish multigeneration registers listing 1.5 million individuals with micro data on mortality and fertility to investigate short-term (first birth risk) and long-term (childlessness at age 45) effects of parental death on adult children's fertility. The principal finding is that parental death during reproductive age affects children's fertility and this effect is mainly short term. The effects differ to some degree between men and women and depend on the stage of the life course in which the bereavement occurs. Younger individuals experiencing a parental death have a significantly higher first birth risk after the parental death compared with peers who did not experience a parental death. Individuals older than 23 who experience a parental death have no or lower first birth risk after the parental death compared with baseline. Men, compared with women, are more likely to end childless if they experience a parental death.

Fertility after natural disaster: Hurricane Mitch in Nicaragua

This investigation evaluates the effect of Hurricane Mitch on women's reproductive outcomes throughout Nicaragua. This research aim is achieved by analyzing a unique Nicaraguan Living Standards Measurement Study panel dataset that tracks women's fertility immediately before and at two time points after Hurricane Mitch, combined with satellite-derived municipality-level precipitation data for the 10-day storm period. Results show higher odds of post-disaster fertility in municipalities receiving higher precipitation levels in the immediate post-Hurricane Mitch period. However, fertility normalizes between disaster and non-disaster areas four to six years after the storm. These findings suggest that the disruptive effects of a natural disaster such as Hurricane Mitch can have an initial stimulative effect on fertility but the effect is ephemeral.

The impact of armed conflict on adolescent transitions: a systematic review of quantitative research on age of sexual debut, first marriage and first birth in young women under the age of 20 years

Background

Young women in conflict-affected regions are at risk of a number of adverse outcomes as a result of violence, economic deterioration and the breakdown of community structures and services. This paper presents the findings of a systematic review of quantitative literature reporting how key sexual and reproductive health (SRH) outcomes among young women under the age of 20 years are affected by exposure to armed conflict; namely, sexual debut, first marriage and first birth. Increases in these outcomes among young women are all associated with potential negative public health consequences. It also examines and documents possible causal pathways for any changes seen.

Methods

To fit with our inclusion criteria, all reviewed studies included outcomes for comparable populations not exposed to conflict either temporally or spatially. A total of 19 studies with results from 21 countries or territories met our inclusion criteria; seven presented findings on marriage, four on fertility and eight on both of these outcomes. Only one study reporting on sexual debut met our criteria.

Results

Findings show clear evidence of both declines and increases in marriage and childbirth among young women in a range of conflict-affected settings. Several studies that showed increases in marriage below the age of 20 years reported that such increases were concentrated in the younger teenagers. Trends in fertility were predominantly driven by marriage patterns. Suggested causal pathways for the changes observed could be grouped into three categories: involuntary, gender and psycho-social and economic and material factors.

Conclusion

The review reveals a paucity of literature on the impact of conflict on SRH outcomes of young women. Further quantitative and qualitative studies are needed to explore how conflict influences SRH events in young women over both the short- and longer-term.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2868-5) contains supplementary material, which is available to authorized users.

One-Parent Families in Contemporary Cambodia

Non-marital births and divorce remain rare in Cambodia. Due to dramatic levels of adult mortality reached during the late 1970s, growing up with a single parent is not. Using nationally representative, cross-sectional data, we estimate that about 12% of children under age 18 co-reside with only one of their biological parents. Using longitudinal data representative of the Mekong River Valley, we find this proportion to be declining. Nearly half of these children live in nuclear families (single parent with or without a step-parent), even though they live in multigenerational families more frequently than children who live with both their parents, especially, when young and not living with their mother. Last, we consider differences in socioeconomic conditions and child educational outcomes by number of co-residing parents.

The boundaries of genocide: Quantifying the uncertainty of the death toll during the Pol Pot regime in Cambodia (1975-79)

The range of estimates of excess deaths under Pol Pot's rule of Cambodia (1975-79) is too wide to be useful: they range from under 1 to over 3 million, with the more plausible estimates still varying from 1 to 2 million. By stochastically reconstructing population dynamics in Cambodia from extant historical and demographic data, we produced interpretable distributions of the death toll and other demographic indicators. The resulting 95 per cent simulation interval (1.2-2.8 million excess deaths) demonstrates substantial uncertainty over the exact scale of mortality, yet it still excludes nearly half of the previous death-toll estimates. The 1.5-2.25 million interval contains 69 per cent of the simulations for the actual number of excess deaths, more than the wider (1-2 million) range of previous plausible estimates. The median value of 1.9 million excess deaths represents 21 per cent of the population at risk. Supplementary material for this article is available at: http://dx.doi.org/10.1080/00324728.2015.1045546.

The effects of mortality on fertility: population dynamics after a natural disaster

Understanding how mortality and fertility are linked is essential to the study of population dynamics. We investigate the fertility response to an unanticipated mortality shock that resulted from the 2004 Indian Ocean tsunami, which killed large shares of the residents of some Indonesian communities but caused no deaths in neighboring communities. Using population-representative multilevel longitudinal data, we identify a behavioral fertility response to mortality exposure, both at the level of a couple and in the broader community. We observe a sustained fertility increase at the aggregate level following the tsunami, which was driven by two behavioral responses to mortality exposure. First, mothers who lost one or more children in the disaster were significantly more likely to bear additional children after the tsunami. This response explains about 13 % of the aggregate increase in fertility. Second, women without children before the tsunami initiated family-building earlier in communities where tsunami-related mortality rates were higher, indicating that the fertility of these women is an important route to rebuilding the population in the aftermath of a mortality shock. Such community-level effects have received little attention in demographic scholarship.

A Demographic Perspective on Family Change

Demographic analysis seeks to understand how individual microlevel decisions about child-bearing, marriage and partnering, geographic mobility, and behaviors that influence health and longevity aggregate to macrolevel population trends and differentials in fertility, mortality and migration. In this review, I first discuss theoretical perspectives-classic demographic transition theory, the perspective of the "second demographic transition," the spread of developmental idealism-that inform demographers' understanding of macrolevel population change. Then, I turn to a discussion of the role that demographically informed data collection has played in illuminating family change since the mid-20th century in the United States. Finally, I discuss ways in which demographic theory and data collection might inform future areas of family research, particularly in the area of intergenerational family relationships and new and emerging family forms.

How community organizations moderate the effect of armed conflict on migration in Nepal

This study analyses micro-level variability in migration during armed conflict in Nepal. The analysis is based on a multi-dimensional model of individual out-migration that examines the economic, social, and political consequences of conflict and how community organizations condition the experience of these consequences and systematically alter migration patterns. Detailed data on violent events and individual behaviour during the Maoist insurrection in Nepal and multi-level event-history analysis were used to test the model. The results indicate that community organizations reduced the effect of conflict on out-migration by providing resources that helped people cope with danger, as well as with the economic, social, and political consequences of the conflict. The evidence suggests that the conflict caused the population to be systematically redistributed in a way that will probably affect its future socio-demographic composition--the extent of the redistribution depending on the resources available in each community.

A micro-level event-centered approach to investigating armed conflict and population responses

In this article, we construct and test a micro-level event-centered approach to the study of armed conflict and behavioral responses in the general population. Event-centered approaches have been successfully used in the macro-political study of armed conflict but have not yet been adopted in micro-behavioral studies. The micro-level event-centered approach that we advocate here includes decomposition of a conflict into discrete political and violent events, examination of the mechanisms through which they affect behavior, and consideration of differential risks within the population. We focus on two mechanisms: instability and threat of harm. We test this approach empirically in the context of the recent decade-long armed conflict in Nepal, using detailed measurements of conflict-related events and a longitudinal study of first migration, first marriage, and first contraceptive use. Results demonstrate that different conflict-related events independently shaped migration, marriage, and childbearing and that they can simultaneously influence behaviors in opposing directions. We find that violent events increased migration, but political events slowed migration. Both violent and political events increased marriage and contraceptive use net of migration. Overall, this micro-level event-centered approach yields a significant advance for the study of how armed conflict affects civilian behavioral responses.

Instability, investment, disasters, and demography: natural disasters and fertility in Italy (1820-1962) and Japan (1671-1965)

This article examines whether natural disasters affect fertility-a topic little explored but of policy importance given relevance to policies regarding disaster insurance, foreign aid, and the environment. The identification strategy uses historic regional data to exploit natural variation within each of two countries: one European country-Italy (1820-1962), and one Asian country-Japan (1671-1965). The choice of study settings allows consideration of Jones' (The European miracle, Cambridge University Press, Cambridge, 1981) theory that preindustrial differences in income and population between Asia and Europe resulted from the fertility response to different environmental risk profiles. According to the results, short-run instability, particularly that arising from the natural environment, appears to be associated with a decrease in fertility-thereby suggesting that environmental shocks and economic volatility are associated with a decrease in investment in the population size of future generations. The results also show that, contrary to Jones' (The European miracle, Cambridge University Press, Cambridge, 1981) theory, differences in fertility between Italy and Japan cannot be explained away by disaster proneness alone. Research on the effects of natural disasters may enable social scientists and environmentalists alike to better predict the potential effects of the increase in natural disasters that may result from global climate change.

DIVERSITY AND CHANGE IN CAMBODIAN HOUSEHOLDS, 1998-2006

Extant ethnographic studies suggest that the nuclear family has been the predominant living arrangement in Cambodia, and the country's rapid socioeconomic transformation since the early 1990s may have accentuated that dominance. To examine these claims, we analyse here household structure in Cambodia between 1998 and 2006, based on data from the 1998 Census, two nationally-representative surveys (2000 and 2005), and a continuing demographic surveillance system (from 2000 on). Our analysis confirms the large prevalence of nuclear families, but not an unequivocal trend toward their increasing prevalence. First, nuclear families are less prevalent in urban than in rural areas, and nationwide, they appear to have receded slightly between 2000 and 2005. We find that increases in the prevalence of extended households correspond to periods of faster economic growth, and interpret these contrasted trends as signs of tensions during this transitional period in Cambodia. While the nuclear family may still be the cultural norm, a high degree of pragmatism is also evident in the acceptance of other living arrangements, albeit temporary, as required by economic opportunities and housing shortage in urban areas.