Since taking care of grandchildren might be a highly demanding job which requires constant energies, consistent attentions to their young grandchildren ^[1], it could exert influences on grandparents’ physical and emotional health. For example, taking care of their grandchildren may reduce grandparents’ own time for self-care such as missing the medical appointment and they are likely to have more physical health issues ^[2]. In the USA, grandparents being caregivers of their grandchildren normally results in poor physical conditions such as coronary heart disease, hypertension or body pain ^[3]. Besides physical health issues, grandparents are also likely to have emotional issues during the grandchildren rearing process. Raising small children again may be stressful or overwhelmed and thus results in different kinds of emotional health issues such as anxiety or depression ^[4]. Spending nearly every day with their grandchildren also strains their social activities and lets them become more isolated from their social relations ^[5]. In other words, grandparents may encounter more functional/activity limitations during this process, which may decrease their own life quality. Taking care of grandchildren also means more responsibilities, grandparents may fear for their grandchildren’s future well-being because of their disability and death in the future ^[6]. If grandparents cannot hand the caregiver role of their grandchildren well, this job will eventually become a burden or stressor and bring deteriorating physical health and emotional issues to grandparents ^[7].

However, there are also positive effects of being caregiver to their grandchildren on grandparents. Compared with grandparents who do not provide caregiving to their grandchildren, those who take care of their grandchildren with long hours are likely to have better cognitive functions ^[8]. To be more specific, taking care of grandchildren helps elder grandparents maintain their mental capacities in later life, they are less likely to develop diseases such as dementia ^[9]. Frequent interactions with their grandchildren prevents or halt grandparents’ cognitive aging process, which leads them a more vibrant and active life ^[8]. Grandparents also get benefits of physically exercising more during this process ^[10]. On the aspect of emotional health, there are also positive effects of taking care of their grandchildren. During this process, many grandparents start to feel the sense of purpose and meaning in life again after the retirement and their ties with their adult children and grandchildren also get strengthened ^[11]. Grandparents may also think of the caregiving experience as positive because it provides another chance for them to make up mistakes they made with their own children and give them more opportunities to education their grandparents and improve their parenting styles ^[12].

Cultural differences in grandparents raising their grandchildren exist between western cultures represented by the USA and eastern cultures represented by China. Grandparents taking care of their grandchildren is a common phenomenon in China due to Chinese traditions which emphasizes the family harmony, collective well-being, intergenerational exchanges and filial responsibilities ^[7]. China’s unique philosophies, Buddhism and Taoism, play important roles in forming these cultural values. While Chinese Buddhism accentuates prioritized role of family in Chinese society and harmonious relations among family members ^[13], Taoism emphasizes the importance of harmony in interpersonal relations and relations between the nature and the humans ^[14]. These philosophies underline the important role that family play in Chinese cultures. Besides cultural factors, grandparents taking care of their grandchildren also appears in the context in which their adult children need to work full-time and the child care services are either too expensive (in big cities) or too scarce (in remote areas) ^[15][7]. Grandparents serving as their grandchildren’s caregiver is particularly obvious in rural China. Due to the fast development of urbanization in China since the 1980s, up to 220 million migrant workers from rural areas move to urban areas to seek for more job opportunities, which leave around 58 million children behind in rural areas ^[15], grandparents therefore undertake the role of parents and become caregivers to their grandchildren. This also cause a new phenomenon named “left-behind grandparents” ^[16], these grandparents live in rural China and their main job is to look after their children, most of them are facing financial burdens and wish their adult children could come back. “left-behind grandparents” appears together with “left-behind children”, the mental and physical health of this population needs more attentions from the public ^[17]. Even though in urban areas where child care services are available, nearly all grandparents still prefer to voluntarily take care of their grandchildren. Not only because this can reduce their adult children’s financial burdens on child care services but also taking care of their own grandchildren is a more effective way to maintain family harmony ^[7].

In the USA, taking care of grandchildren is not a necessary responsibility of grandparents. They often take care of their grandchildren when their adult children get into troubles such as substance abuse, incarceration or parental death ^[6][18]. Differences also exist in different ethnicities in the USA, White individuals generally regard individual independence as more important, so grandparents are less likely to take care of their grandchildren. However, Black and Latino individuals are more likely to regard looking after grandchildren as a family tradition and are more willing to provide help for their adult children ^[19]. Ethnic differences in grandparents looking after their grandchild reflect different cultural values that different ethnic groups hold. To be more specific, Black grandparents are more likely to provide guidance and discipline to their grandchildren due to their flexible family system in which relatives, non-blood or fictive kin are all willing to help each other ^[7]. Latino families have a strong preference to live together and keep frequent contact with family members because most of them are immigrants or first-generation born in the USA, they are more likely to live and function as a unit and grandparents play important roles in stabilizing this family unit as family leaders ^[20]. Although White grandparents are less likely to raise their grandchildren ^[21], they have more cognitive or physical burdens of taking care of grandchildren compared with other ethnic groups ^[22], mainly because their caregiver roles are less normative and they rely more on remote or companionate parenting styles rather than correct or discipline like what Black or Latino grandparents do ^[23]. Grandparents taking care of their grandchildren in western cultures is often caused by involuntary events or crisis and it is more like a solution to a problem not an initiative desire, which is a distinct difference from that in eastern cultures ^[6].