Abstract

Background

People who have experienced the Chinese Great Famine (1959鈥�1961) in their fetal period are getting old. It is particularly important for China鈥檚 response to the ageing of this cohort to study the impact of the Holodomor on disability.

Method

This paper presents an empirical analysis that utilizes the survey data from the 2018 China Health and Retirement Longitudinal Study (CHARLS), employing a cohort Difference-in-Differences (DID) modeling approach. It integrates the excess mortality rate (EDR) from China鈥檚 Great Famine with the 2018 CHARLS survey data, selecting suitable control and experimental groups for a comprehensive study. The empirical analysis is conducted using the cohort DID model, comprising a total of 11,567 samples.

Results

This study found that the experience of famine would increase the level of disability in the population, with each 0.1% increase in excess mortality increasing the level of IADL by approximately 0.019. This experience during the fetal period will increase the incidence of handicaps, mainly in the brain and hearing. This thesis finds strong heterogeneity across gender and between urban and rural areas.

Conclusions

China鈥檚 long-term care capacity should be improved, with attention paid to the rural disabled population and to the health of pregnant women and fetuses.

Introduction

The Chinese Great Famine pertains to a three-year catastrophic event in the country spanning from 1959 to 1961, resulting in an estimated death toll ranging between 16.5 and 45听million individuals. However, the disaster not only killed a large number of people, but also had long-term effects on the health of the survivors. Based on Barke鈥檚 鈥渇etal origins hypothesis鈥�, They found that malnutrition in early gestation hinders embryonic development and may result in small babies with asymmetrical birth weights, and that malnutrition in mid-gestation may alter the interaction between the fetus and the placenta, which may become smaller or hypertrophied. Malnutrition in the second trimester may result in fetal wasting as its amino acids are transferred to the placenta for energy production. Finally, they concluded that malnutrition in pregnancy alters the relationship between glucose and insulin, and between growth hormone and the insulin-like growth factors (IGFs) [1]. They posited that the fetalor early childhood stage represents a critical period of growth and development, wherein exposure to adverse nutritional and health conditions can impact the maturation of both immune system and vital organs. Consequently, this influences the trajectory of an individual鈥檚 health throughout their lifespan [1,2,3,4,5]. Consequently, this heightened vulnerability may subsequently elevate the risk of dementia and disability among older adults,. Many researchers also believed that the early years of the life course had significant impact on physical health, mental health, cognition, and even religion in adulthood [6,7,8,9,10,11].

This suggests that childhood adversity has a direct effect on the health of middle-aged and older adults, persisting even after controlling for factors such as socio-economic status and lifestyle. The impact of malnutrition on the long-term health and mental well-being of fetuses, infants, and children is widely acknowledged [4, 12,13,14,15,16]. Childhood adversity can indirectly affect the health of middle-aged and older adults through psychological and social resources in addition to its direct physical effects. It is influenced by early life conditions, which determine subsequent access to health resources and exposure to health risks. As individuals age, there is an accumulation of resources or risks, leading to the exacerbation of health disparities. The health status early in life is believed to exert an influence on the health status in old age through its impact on subsequent developments, such as social and economic statuses [17,18,19].

To more accurately ascertain the impact of 鈥減regnancy exposure鈥� on the health of older adults, numerous researchers have employed exogenous shocks such as wars, famines, natural disasters, and economic downturns [6, 11, 20,21,22]. It has been observed that early-life exposure to malnutrition, exerts a significant impact on self-perceived health during old age, elevates the likelihood of developing chronic ailments, and potentially impairs cognitive functioning in elderly individuals [23]. It has been found that female babies who experienced famine in the womb have a higher risk of diabetes, while male babies who experienced the Cultural Revolution have lower cognitive abilities [24]. It has also been suggested that exposure to drought in infancy increases the rate of disability in later life by 3.5鈥�5.2 per cent, with the effects concentrated on physical and mental disability, with the greatest impact on males [6]. Lumey and Stein find consistent associations between prenatal famine and adult body size, diabetes and schizophrenia [9]. Indirect exposure to prolonged conflict in utero and in early childhood has been found to be associated with developmental delays and increased underweight in India [15]. In Colombia, individuals exposed prenatally to unfavorable rainfall shocks are more likely to report severe mental illness, have fewer years of education, increased illiteracy and are less likely to work [25]. In utero exposure is associated with a 7.91% point increase in the likelihood of childhood asthma [26]. However, to date, no study has investigated the impact of the Holodomor on the functional impairment of older individuals, which is a crucial matter that necessitates immediate attention within the context of China鈥檚 rapidly aging population and advanced aging trends.

Currently, with the aging population in China progressing, individuals who experienced the Great Famine during their prenatal development have either entered or are about to enter old age. It is crucial to investigate whether the adversity faced during their fetal life will impact their functional capacity in old age, potentially leading to a higher degree of incapacity and an increased demand for long-term care insurance. The exploration of this issue has a direct impact on the future of our health insurance and the ongoing development and maintenance of long-term care insurance. The primary contributions of this study are threefold: firstly, it enhances the existing body of research on the long-term health implications and potential disabilities associated with fetal exposure to famine; Second, it explores gender and the heterogeneity of how the population is affected between urban and rural areas. and thirdly, it establishes a significant association between prenatal famine exposure and increased prevalence of disability, particularly in relation to brain function and hearing.

The Chinese great famine

This study investigates the impact of quantifying the consequences of an exogenous shock, namely the Chinese Great Famine, on the extent of disability in later life. Referred to in the relevant literature, this paper utilizes the period from 1959 to 1961, during which mortality rates were significantly higher compared to other non-famine years, as a measure of excess mortality rates [24, 27]. This approach is employed to assess the severity of the famine across different provinces. The excess mortality is calculated by subtracting the average annual mortality rate for 1954鈥�1958 from the famine year (1959鈥�1961) in increments of 0.1%. In non-famine years, the severity is negligible. The excess mortality rates for specific provinces arepresented in Appendix 1, Table A. The data were ranked based on excess mortality, using EDR鈥�=鈥�3 as the threshold. The experimental group consisted of the 14 provinces with EDR鈥�>鈥�=鈥�3 (edr鈥�=鈥�1), representing regions heavily impacted by the Great Famine. Conversely, the control group comprised of the 15 provinces with EDR鈥�<鈥�3 edr鈥�=鈥�0, symbolizing areas less affected by the shock of the Great Famine.

In this study, we employ the birth cohort design method in conjunction with the charls2018 data (China Health and Elderly Tracking Survey) to examine the sample population born between 1949 and 1966. The birth cohort is categorized based on the period affected by the Great Famine: Birth cohort 1 comprises samples born in 1962鈥�1965, unaffected by the Holodomor; Birth cohort 2 consists of samples born in 1950鈥�1953, exposed to the Holodomor during childhood; Birth cohort 3 includes samples born in 1954鈥�1958, impacted by the Holodomor during infancy and early childhood; Finally, birth cohort 4 encompasses samples born in 1959鈥�1961, experiencing exposure to the Holodomor during fetal life. In the study conducted by Chen (2020), the classical cohort double-difference method was employed to establish the framework of a cohort double-difference model. This involved constructing an interaction term between birth cohorts and the degree of affectedness, enabling a more accurate estimation of the impact of early-life exposure to the Great Famine on old-age incapacity [28].

Data and variable selection

This study utilizes data from the 2018 China Health and Aging Tracking Survey (CHARLS), incorporating measurement questions and relevant disability indicators within the survey questionnaire. The Instrumental Activities of Daily Living (IADL) serves as an objective indicator for assessing health status [29]. The IADL scale was employed in this study to assess the level of disability among elderly individuals, with IADL scores ranging from 5 to 20. Higher scores were indicative of greater impairment in IADL performance. The presence of disability is a crucial factor in measuring incapacity, and it has been utilized as a measure of incapacity in the Annals of Health Statistics. In the robustness test, we used whether a disability on one of brain, limb, hearing, vision, or speech occurred as a proxy variable. In this study, covariates such as household type, gender, marital status, education level, and pension availability were selected. After performing data cleaning, the sample size was reduced to 11,567 with IADL as the independent variable. The descriptive statistics for this sample are presented in Table听1.

Table 1 Descriptive statistics

Empirical analysis

Empirical model

The impact of the Holodomor on population health is a unique exogenous natural experiment, and this study draws on the common practice of studying other correlates of the Chinese Holodomor by using the cross-sectional difference-in-differences (DID) method to rigorously assess the causal impact of the Holodomor [24]. In the difference-in-differences model, 鈥淚ADL鈥� was employed as an explanatory variable, while the core explanatory variable consisted of the interaction term between the cohort variable (Cohort) and the influenced degree variable (EDR). The aforementioned control variables were also incorporated into the model using the following formula:

$$\begin{aligned}{Y}_{ics}&={\alpha\:}+{{\beta\:}}_{\text{c}}\text{*}{\text{C}\text{o}\text{h}\text{o}\text{r}\text{t}}_{\text{i}\text{c}}\text{*}{\text{E}\text{D}\text{R}}_{\text{s}}+{\gamma\:}{\text{X}}_{\text{i}\text{c}\text{s}}\\&\quad+{{\delta\:}_{c}\text{a}\text{g}\text{e}}_{\text{i}\text{c}}+{{\theta\:}_{s}\text{e}\text{d}\text{r}}_{\text{s}}+{{\epsilon\:}}_{\text{i}\text{c}\text{s}}\end{aligned}$$

(1)

In Eq.听(1), i represents individual, c represents cohort(c鈥�=鈥�1,2,3,4), s refers to region. Y_ics represents the Instrumental Activities of Daily Living (IADL), 伪 denotes a constant term, 尾_c signifies the impact of the Holodomor on the population鈥檚 level of disablement, and 蔚_ics refers to the residual error. X_ics encompasses control variables such as gender, household registration, marital status, education level, pension availability, participation in urban and rural residents鈥� medical insurance programs, and engagement in regular exercise. Furthermore, in line with the aforementioned discussion, there exists a robust correlation between age and disability. Therefore, this study incorporates controls for fixed effects of both age (age_ic) and the extent of disaster (edr_s) to ensure a more rigorous analysis.

Empirical results

The results of the cross-sectional DID regressions are presented in Table听2. Cohort 1 was designated as the control group, while the remaining cohorts were considered as the experimental group in all regression models. The regression results obtained from Eq.听(1) are subjected to analysis. In regression model 4, the study findings revealed a statistically significant increase in incapacitation levels among individuals who experienced the Holodomor during pregnancy compared to those who did not (coefficient鈥�=鈥�0.017), while controlling for Model 1 as the full sample data and Models 2鈥�4 representing Cohort 1 and Cohorts 2鈥�4, respectively. This result is not statistically significant in the other three regression models, indicating that only exposure to the Great Famine during fetal development elevates the level of incapacitation in old age within the population. Additionally, incorporating an age fixed effect effectively controls for the confounding influence of age on IADL鈥斺�擨n the remaining three regressions, the experimental group consisted of older individuals; however, no statistically significant distinction was observed in terms of disability severity.鈥�

Table 2 Empirical results by cohort

PSM-DID

To accurately assess the impact of famine exposure during pregnancy on incapacitation levels, this study employs the PSM-DID method for further investigation. The propensity score matching method (PSM) can mitigate the estimation bias caused by the omission of important control variables by employing propensity score matching to align the data, thereby effectively reducing discrepancies between the experimental and control groups and yielding more robust findings. In the empirical analyses conducted in this study, the cohorts were utilized as natural experimental and control groups. Therefore, propensity scores were matched with Cohort 1 serving as the experimental group and Cohort 4 acting as the control group. The standard deviation values of the covariates exhibited a significant decrease following matching, with the majority of variables experiencing a reduction of 80% or more. Furthermore, an overwhelming majority of samples fell within the common support domain. Therefore, the matching process is conducted based on data processing after performing regression using formula (1) to obtain the results presented in Table听3 below. Consistent with the findings of the previous study, exposure to Holodomor during pregnancy was associated with a significant increase in disability among older adults, indicated by a coefficient of 0.019. This means that for every 0.1% increase in the excess mortality rate, the level of disability will increase by 0.019. The regression results of Models 6鈥�7, employing nearest neighbor matching, nearest neighbor matching with calipers, and radius matching respectively, closely approximate the aforementioned findings. This indicates the robustness of the empirical analysis conducted in this study.

However, the regression coefficients in this study were computed based on the sample鈥檚 status at the time of interview, primarily examining a cohort of individuals who experienced Holodomor during pregnancy. This particular sample group consisted predominantly of young participants and did not encompass a period characterized by a rapid increase in disability. The level of disability increases exponentially with age, and beyond the ages of 75 and 85, individuals who were exposed to the Holodomor while in utero will face a significant surge in future disability rates, surpassing the current measurements by a substantial margin. Constrained by the constraints of the actual circumstances, this study is capable of making only one prediction.

Table 3 PSM-DID

Parallel trends

The reliability and credibility of the results were further tested using event analysis with the last period, i.e. the sample born in 1966, as the base period. As shown in Fig.听1, the samples born in 1963, 1964 and 1965 are not different from 0 at the 95% confidence interval. It is worth noting that the regression coefficient of the 1962 sample is significantly different from 0. However, this paper considers this to be a normal phenomenon because some of the 1962 birth samples were fetuses in 1961, and is still affected by the Great Famine at the fetal stage. Therefore, the paper passes the parallel trend test.

Fig. 1

Parallel trends

Robustness tests and heterogeneity analysis

Exclusion of effects caused by accidental injury

In the robustness test, this paper needs to exclude cases of physical disability brought about by transportation, natural disasters and other circumstances, etc. There is a relevant variable in the charls 2018 data, which examines whether the sample has experienced transportation accidents or major accidents, and whether the injuries brought about by the accidents have affected physical activities. Therefore, this paper conducts a robustness test based on the relevant variables to exclude the sample of residents who are unable to perform normal activities due to accidental disasters. Then regression (using the same method as the main regression), the results are shown in Table听4, after excluding the sample of incapacitation caused by accidents, the empirical results of this paper are still significantly positive, proving the credibility of this paper.

Table 4 Exclusion of effects caused by accidental injury

Placebo test

This paper conducts a placebo test to verify that the policy effect was brought about by the Holodomor and not some other cause. In this paper, by disrupting the allocation of the original experimental and control groups, and then re-randomly allocating the experimental and control groups, and in the regression using the disrupted experimental and control groups, the specific results are shown in Table听5, the regression coefficients of the disrupted experimental and control groups are all not significantly different from 0, so the placebo test of this paper passes.

Table 5 Placebo test

Substitution of variables

Some scholars have not directly employed the Instrumental Activities of Daily Living (IADL) as a metric for assessing disability, while certain studies have utilized disability incidence as an indicator of impairment. For instance, the 2013 Fifth National Health Service Survey Analysis Report employed vision impairments, hearing impairments, speech difficulties, and mobility limitations as indicators of disability. Therefore, this study incorporates one of the five disability categories, namely physical disability/brain damage/blindness/deafness/mute status, as an independent variable for explanatory purposes. Considering the qualitative nature of all aforementioned dependent variables as dummies, we construct the interaction term between the subgroup of excess mortality and birth cohort using a probit model, resulting in Eq.听(2).

$$\:\text{P}\text{r}\left(\text{y}\right)={\upalpha\:}+{{\upbeta\:}}_{\text{i}}\text{*}{\text{C}\text{o}\text{h}\text{o}\text{r}\text{t}}_{\text{i}}\text{*}{\text{e}\text{d}\text{r}}_{\text{i}}+{\upgamma\:}{\text{X}}_{\text{i}}+{{\upepsilon\:}}_{\text{i}}$$

(2)

The regression results, based on the samples from Cohort 1 and Cohort 4, are presented in Table听6. The explanatory variable in Model 14 was chosen as 鈥渢he presence or absence of any of the five types of disabilities,鈥� while the selection process for samples and variables remained consistent with that used in the main regression analysis. This study reveals that exposure to the Holodomor during pregnancy significantly increases the likelihood of disability in old age, with statistical significance at the 5% level, thereby affirming the robustness of our primary regression findings. It was also observed that among the five primary disabilities, the Holodomor predominantly augmented the prevalence of cerebral impairments and auditory deficiencies.

Table 6 Incidence of disability

Gender heterogeneity

Among the numerous studies pointing out that exposure to natural disasters during fetal life is extremely heterogeneous between males and females, the article by wang (2022) mentions that female infants who experienced famine in utero had a higher risk of diabetes, while male infants who experienced the Cultural Revolution had lower cognitive abilities [24, 30]. To gain further insights into this matter, the present study introduces an interaction term between gender and subgroups of excess mortality, utilizing both Cohort 1 and Cohort 4 samples, followed by conducting regression analyses. The empirical results are shown in the first column of Table听7 (Model 20), revealing a significant degree of heterogeneity between males and females. Exposure to the effects of the Holodomor during fetal development resulted in significantly higher levels of disability for males compared to females, with a statistical significance of 5 per cent.

Urban-rural heterogeneity

The extensive body of literature on the Holodomor indicates that rural areas were disproportionately affected by the Holodomor compared to urban populations. In light of the Holodomor鈥檚 impact, this study examines whether rural residents experience a higher prevalence of disabilities compared to their urban counterparts by incorporating an interaction term between place of residence and excess mortality. The empirical results are shown in the second column of Table听7 (For ease of interpretation and to preserve the sample as much as possible, with reference to the urban-rural classification codes of the National Bureau of Statistics (NBS), this paper collectively refers to the combined urban-rural areas and urban samples as towns/cities when analyzing the urban-rural heterogeneity, with id鈥�=鈥�0 when the sample resides in rural areas and id鈥�=鈥�1 when the sample resides in towns/cities.), indicating that rural populations exposed to the Holodomor during gestation exhibited significantly higher levels of instrumental activities of daily living (IADLs) compared to their counterparts living in town/city. The findings reveal a significant heterogeneity of Holodomor shocks between rural and urban residents, thereby providing additional empirical support for the notion that rural inhabitants exhibit a heightened demand for long-term care insurance.

Table 7 Gender heterogeneity

Discussion

Using data on excess mortality from the 1959鈥�1961 Holodomor as well as 2018 charls data for an empirical study, this paper explores whether experiencing the Holodomor during pregnancy leads to higher levels of old-age disability with the help of the empirical methodology of cohort DID. The research in this paper is valuable both in terms of reality and literature, in reality the results of this paper provide an early warning to the Chinese government, and in terms of literature, enriching the relevant literature on disablement research.

In other literature, little attention has been paid to the impact of disability among those who experience famine in their foetal life, but in China, where ageing is a serious problem, this is very important because disability affects not only the individual, but also the family and the social workforce. The results of the paper enhances the scholarly understanding of the Holodomor鈥檚 impact on incapacitation. As individuals who were exposed to famine during their prenatal development reach advanced age, there is a significant increase in the prevalence of disability, thereby exerting an inevitable impact on social progress and imposing a greater burden of caregiving on society. Firstly, in comparison to other groups, this particular group exhibits a higher degree of disability and lower self-care capacity, thereby imposing a substantial burden on the respective families it belongs to [31,32,33]. Additionally, it constrains the family labor force, leading to diminished household income and a decreased sense of well-being [33,34,35]. Increasing levels of incapacity will also lead to increased demand for medical services and long-term care, but at this stage, the distribution of long-term care resources throughout China and long-term care insurance are not widespread enough to provide adequate protection [36,37,38,39]. The findings of this paper provide a warning of the range of problems that can occur.

There are still some limitations to this paper; the data used at this stage are from 2018, and the cohort of people who suffered the Holodomor as foetuses is not at a high prevalence stage. However, the high rate of increase in disability in this population is likely to be after 2030, and it is not possible at this stage of the paper to obtain this observational data to obtain an accurate estimate. In future studies, we may be able to model the trajectory of the onset of incapacitation in this population through relevant methods to predict the eventual extent of incapacitation and to further study the social impact of this group.

Conclusion

This study establishes a fundamental database by integrating charls 2018 data with excess mortality rates across provinces during the Holodomor, aiming to investigate whether prenatal exposure to the Holodomor contributes to an elevated prevalence of old-age disability within the population. The empirical study yielded the following findings: firstly, exposure to famine during the fetal period is associated with an elevated level of disability; secondly, experiencing famine during the fetal period raises the incidence of disabilities, primarily affecting brain function and hearing ability; thirdly, Third, male fetuses are more disabled after exposure to famine compared to females. Lastly, rural populations were disproportionately affected by the famine.

This paper makes the following recommendations regarding the impact of the Holodomor on the population鈥檚 incapacitation and its subsequent impact on socio-economic development: first, China must improve care resources and promote the nationwide accessibility of institutions that integrate health care and nursing care to cope with possible future rises in the demand for care, in order to prevent the demand for long-term care from crowding out health-care resources. Second, attention should be paid to the long-term care needs of rural populations, whose lower economic status and poorer access to health care exacerbated the effects of the Holodomor on disability, and who therefore need to further improve family doctor teams in rural areas and establish a comprehensive network of health and care services, as well as provide financial assistance through long-term care insurance. Thirdly, the health of pregnant women and foetuses should be safeguarded, the welfare of pregnant women and infants should be improved, a financial assistance mechanism for poor pregnant women should be set up, the nutrition of pregnant women should be safeguarded during pregnancy, and the subsidies for women鈥檚 maternity check-ups during pregnancy should be increased, among other things.