1. Introduction
China has become an aging society since the beginning of the new century [
1,
2]. According to the 2019 Chinese census, the number of people aged 60 years or above in China has reached 249 million by the end of 2018, accounting for 17.9% of the total population in the country. Population aging has posed potential challenges on the social security systems in China, especially in rural areas [
3]. Due to limited coverage and insufficient benefits provided by public pension and health insurance systems [
4], adult children remain the primary source of financial and instrumental support for their elderly parents [
1]. Although the new cooperative medical scheme in rural China has substantially improved rural residents’ use of healthcare services, it has not reduced out-of-pocket expenses for patients [
5]. Therefore, the traditional home-based care for the elderly has been challenged, especially when their adult children are migrant [
6]. The massive migration of younger population from rural to urban areas has threatened to erode the foundation of traditional family support relationships [
7,
8,
9]. Therefore, investigating how adult child migration affects the health of left-behind parents comprises an important research direction.
A number of studies have dealt with the relationship between adult child migration and their parental health (e.g., [
10,
11,
12,
13]). The literature provides mixed results for the impacts of child migration on parental health (e.g., [
2,
14,
15]). Intuition suggests that adult child migration is detrimental to health of the left-behind parents (e.g., [
4,
13,
16]). For example, Evandrou et al. [
13] indicated that the odds ratio of reporting a disease was higher among older parents with at least one adult child living in another county. Adult child migration indeed increases economic support for left-behind parents, but it forces parents to undertake more intensive farming tasks. Child migration, therefore, may induce the absence of adult children at home, less attention and negative effect on parental health.
Other empirical studies find that the elderly with migrant children may experience better health status [
2,
8]. Ma and Zhou [
14] indicated that the positive impact of adult children migration induced by increased money transfer to the elderly may offset the negative impact arising from decreasing physical care. Yi et al. [
2] also found that the loss of labor power due to migration has a significantly negative effect on parental health, but remittances from migrants can compensate for the adverse effect. Overall, left-behind elderly parents may benefit from migrant children both physically and mentally.
Thus, the empirical evidence on the impact of adult child migration on left-behind parents’ health remains vague. A possible reason may be that the mechanism of time allocation is not clear, although previous literature has generally considered that children migration can improve parental health due to remittances. To the best of our knowledge, few studies have defined and identified the time effect on parental health. For example, Yi et al. [
2] only discussed the impact of time allocation on the health of left-behind parents along with the negative effect caused by labor loss. In our study, we consider the twofold time effect—increased farm work driven by child migration and emotional cohesion—for the first time. In this setting, the effect of time allocation on the health of left-behind parents may be positive or negative. This can be related to the modern telecommunication technologies that are helpful to alleviate the elderly’s loneliness, dispel their negative emotions, and improve their physical and mental health [
17]. The main problem is to distinguish its total net effects (i.e., income transfer, increased farm work, and emotional cohesion) on the health of the left-behind parents.
The issue of endogeneity has not been fully addressed in some of the previous studies, which may be led to biased estimation. One potential obstacle of estimating the causal effect of child migration on the parental health is reverse causality. Giles and Mu [
11] found that the parental health conditions affect the migration decision of their adult children. The methodological challenges have given rise to a series of innovative approaches, including counterfactual framework [
18], quasi-randomized experiments [
19], and instrumental variables. A number of studies have attempted to find instrumental variables for migration (e.g., [
2,
13,
20,
21,
22,
23]), such as migration rates (e.g., [
22]), local industry (e.g., [
2]), and ecological variables (e.g., [
23]). Thus, the instrumental variable estimation is the most popular approach to identify selection into migration.
Few studies have examined the spouse’s health condition and the living arrangement [
1], which are also important to gauge the relationship between migrant children and parental health. Without accounting for the aforementioned variables, the estimates may be biased.
As stated above, the transmission mechanism of adult child migration on parental health is missing or ambiguous in the earlier literature. Much of the previous research analyzes the impact of child migration on parental health from the perspective of financial support, but either ignores the time effect of adult child migration or simply argues that the time effect is negative [
2]. In fact, the time effect is very complex due to the development of modern telecommunication technologies, which may to a large extent alleviate the negative impact of child migration on parents’ emotional solace [
17]. Thus, it cannot be simply concluded that child migration exerts a negative impact on parental health. As stated above, the objective of this study is to investigate the impact of child migration on parental health in rural China, and gauge the effects of the three types of inter-generational support: income transfer, farm work, and emotional cohesion.
The remainder of this study proceeds as follows:
Section 2 outlines the theoretical model, and discusses the choice of instrumental variables to resolve the reverse causality.
Section 3 describes the data used in this study. The econometric model is discussed in
Section 4.
Section 5 presents the empirical findings, and
Section 6 concludes with policy implications.
2. Theoretical Framework
The issues of public health, economics and migration are often intertwisted [
24,
25,
26]. Under China’s rapid economic growth and urbanization, the traditional home-based elderly care in its rural area has been transforming because of adult child migration, among other factors. It has been reported that 88.7% of the elderly need assistance in their daily activities from family members [
4], however, massive rural-to-urban migration in China has profoundly altered the living style of left-behind elderly [
8]. Given the long distance to migrant children, their left-behind parents have to take care of themselves. There are two theoretical premises that may help to gauge the impact of child migration on parental health outcomes, including the effects of economic contribution and time allocation.
First, economic contribution is the core element of the elderly-care system, and it exerts a direct impact on life quality and health of left-behind parents. Migrant children often earn more in other regions, so they can offer better financial support to their parents, which might help to raise parents’ living quality and improve their access to better medical services [
15]. Thus, in this sense, adult child migration might increase parents’ satisfaction with life and improve their health conditions.
Second, time allocation from adult children could also impact elderly health. Migration makes children unable to provide daily care for left-behind parents, and the parents have to carry out more work on farm and housework. This may pose an adverse impact on their physical and mental health. Additionally, adult children’s spiritual consolation is also needed for their parents [
27]. Several studies have found that modern telecommunication technologies are helpful to alleviate parents’ loneliness driven by child migration, dispel their negative emotions, and improve their physical and mental health [
17,
28].
As stated above, child migration has both positive and negative effects on parental health. The net effect of child migration on parental health depends on whether the positive effect (i.e., economic support and emotional cohesion) can compensate for the negative effect from the loss of family labor (i.e., increased farm work). This study investigates these two opposite effects through the above-mentioned channels of adult child migration on the health of left-behind elderly for the first time.
Figure 1 presents the conceptual framework in the detailed manner.
6. Discussion and Conclusions
Using the data from three latest issues of CHARLS for rural areas in China, this study employed the instrumental variable approach to investigate the impact of adult child migration on the health conditions of their parents left behind. We explored the relationship between child migration and the health of elderly parents through three types of inter-generational support (income transfer, farm work and emotional cohesion) for the first time. Our findings provide evidence that child migration significantly lowers parents’ SRH and physical health (i.e., BMI and PADL) and aggravates parents’ depression. From the point of view of inter-generational support, migration of the children induced the burden of farm work which, in turn, posed a significantly negative impact on the health of parents left behind. Moreover, the positive effect of economic support and emotional cohesion was weak and could not compensate for the adverse effect of the increased farm work. Overall, adult child migration exerts significantly negative impacts on parental health. Additionally, parents who are female, poorly-educated, and living with at least one adult child are the most vulnerable groups being in poor health outcomes.
The above-mentioned findings deepen the understanding of the role of traditional inter-generational support in the context of large-scale domestic emigration and population aging in China. Increasing burden of farm work is the major cause of affecting health of left-behind parents. Thus, the rural development policy in China should focus on reduction of farm work for the elderly. In the long-run, the young and middle-aged rural population will continue to leave their parents and opt for work in the cities of China. First of all, it is necessary to establish an effective healthcare insurance system, rural community medical services, and elderly people’s associations to guarantee the living conditions of left-behind seniors, especially, elderly women. Second, communities could establish the self-governing organizations among the elderly, which can increase their mutual assistance and reduce the resentment resulting from child migration. The burden of farm work of elderly parents left behind can be reduced through improved social service system, such as cooperatives or “cultivation assistance” groups that provide cultivation service for the left-behind elderly.