The swift rise in China's ageing population coincides with the rapid advancement of informatization, presenting unparalleled opportunities and challenges in addressing China's ageing issues. From 2010 to 2022, the percentage of internet users within the 50-59 age group escalated from 11.1% to 73.5%, while in the 60 and above age group, it surged from 4.9% to 54.5%. The examination of how internet use impacts the lives of older adults using the latest empirical data has gained increasing significance. Key findings are as follows: It highlights a profound integration of the internet into the lives of older adults; there exists considerable diversity in internet usage patterns among older adults; it remains crucial to recognize the persistent digital divide among older adults, and elevating cybersecurity awareness among them is paramount to safeguard against potential online threats; furthermore, moderate internet use has shown to positively impact healthy ageing and contribute to the subjective well-being of older individuals. These findings underscore the urgent need to create a digital society that accommodates older adults. This necessitates concerted efforts from governments, enterprises, communities, families, and the older adults themselves. Collective participation and collaborative work are pivotal in cultivating an environment that supports and empowers this demographic within the digital landscape.

Using data from 2017 survey on Chinese families' fertility decision under the new fertility policy, this study investigates how childbearing motivation impacts women's second-birth plan in urban China. Results show that higher socioeconomic status is linked to both stronger individualism-oriented and stronger childdevelopment-oriented motivations of childbearing. Meanwhile, individualism-oriented motivation is negatively while childdevelopment-oriented motivation is positively associated with the probability to have a second birth plan. Overall, women who have a higher socio-economic status would have a higher probability to have a plan for a second birth. The KHB decomposition suggests that the two types of childbearing motivation play a mediating role in the relationship between women's socioeconomic status and their plan for a second birth. And the childdevelopment-oriented motivation has a larger mediating effect. This study has important theoretical and policy implications by emphasizing the role of childbearing motivation in women's fertility decisions.

Fertility transition of ethnic minorities is an integral part of the demographic transition of China. Studying fertility transition among different ethnic groups offers a new perspective in understanding fertility transition in China. This study uses multiple waves of micro census to describe fertility transitions of different ethnic minority groups. Utilizing multilevel models, this study also identifies the between and within group determinants of ethnic minority fertility behaviors. Results show that similar to Han Chinese, ethnic minorities also experienced fertility decline over the past forty decades. Yet their rates of decline were modest. Most ethnic minority groups reached near replacementlevel fertility since 2000, and some saw modest increase in the recent decade. There exist heterogeneities within ethnic groups. Different ethnic groups exhibit different fertility patterns. The multilevel analysis results show that ethnicspecific traits had diminishing yet still significant impact on fertility behaviors. Within ethnic group differences account for a larger part of the total fertility variations.

China is experiencing rapid population ageing and witnesses a wide spread of information technology. The rise of novel internet technologies may increasingly influence older adults' daily life. Using data from a survey on midage and older adults' short video application use conducted in 2021, this study investigates the relationships between short video app usage and midage and older adults' social networks, commutation with family members and friends, social inclusion and mental health. Results show that the moderate use of short video app increases midage and older adults' communication with families and friends, expands their social networks, and promotes their social inclusion. We should also acknowledge that older people face many problems and risks in the digital era. Findings suggest that collective efforts should be made by government, corporations, local communities as well as families to mitigate agerelated digital divide.

This study investigates the impact of human mobility on the spatio-temporal dynamics of COVID-19 spread by utilizing daily COVID-19 data of more than 300 cities in China. The spread of COVID-19 in China is characterized by a two-stage pattern, namely the inter-city transmission driven by human mobility in the first stage and the local transmission among family members in the second stage, which have further shaped the spatio-temporal patterns. The impacts of human mobility on the COVID-19 spread are featured by structural differences and dynamic patterns. Temporal movements including tourism and business travel are the main route of transmission at the beginning of COVID-19 outbreak, while internal migrants returning to their hometowns during the Chinese Spring Festival are mainly responsible for the peak outbreak in early February. Both survey data and big data have equally high statistical power in predicting and interpreting the spread of COVID-19, indicating that the combination of the twos strengths would contribute substantially to advancing quantitative research and improving social governance capacity.

This study investigates the association between migration and birth intervals by utilizing data from 2017 China Fertility Survey. By constructing women's life course based on their migration, first marriage and birth date, we explore how different types of migration are associated with women's marriage-first-birth interval and first-second-birth interval using the method of survival analysis. The findings are summarized as following: (1) Migration has a postpone effect on childbearing; (2) However, the effects of migration vary by migrating time. Compared to non-migrants, women who experienced migrating event between marriage and first birth, or between first and second birth significantly prolonged their marriage-first-birth interval and first-second-birth interval respectively. But women who didnt migrate between first marriage and first birth or between first and second birth had shortened intervals compared to non-migrants.

Using 2016 fertility survey data from 12 cities in 6 provinces in mainland China，this study empirically investigates how sex preferences impact couple's intentions for a second child. Specifically, we discuss how the agreement on sex preferences between the husband and wife is related to their intentions for a second child and desire for the sex of second birth. The results suggest that about 59% of the couples have same sex preference, in which the preference for having both a son and a daughter (“Er Nv Shuang Quan”) is the dominant type and no preference is the secondary, while the proportion of only son or daughter preference is low. Couples who have the same sex preference are more likely to reach an agreement about having a second child or not, and they also show the same desire for the sex of second child. Husbands and wives with different sex preferences do not show lower second-child intentions. This is because the sex preference of either husband or wife will lead to higher intentions for a second child. Additionally, for couples who have intentions for a second child, the sex preference of husband rather than wife is more likely to be the same with the desire for the sex of second child.

Using data from the 2016 fertility survey conducted in 12 cities of 6 provinces in mainland China,this study discusses the intergenerational effects on women’s plan for a second child in the era of universal two-child policy.We only focus on the main targeted group of this policy change——married women who are between age 20 and 44 and have only one child in urban China,contributing to the discussions regarding future fertility trend.Overall,the results suggest that parental childcare supports and fertility preferences significantly affect women’s birth plan.Specifically,the probability of having a second child plan is higher if parents can provide childcare assistance,prefer to have two or more grandchildren or have sex preference.Also,family income is positively associated with women’s plan to have a second child and moderates parental effects.The influence of parental sex preference on women’s second child plan is stronger in families with higher income.

Using the 2016 fertility survey data from 12 cities in 6 provinces of urban China，this study empirically investigates family size desire，second childbearing intention and their determinants for married women who have already given birth to one child．We find that 24.4% of women have a timetable plan for the birth of a second child，while 5.1% of women have intention but no timetable．Family backgrounds such as the number of siblings and whether a woman coresides with her parents-in-law have significant impact on the family size desire but are insignificantly associated with the second child- bearing intention．In contrast，financial and care burdens significantly affect women’s second child- bearing intention but are insignificantly associated with the family size desire．Sex preferences exist，meaning that women’s second childbearing intention is higher for those whose first child is a girl．Finally，the gap between women’s family size desire and second childbearing intention is mainly driven by practical factors such as women’s age，family’s financial status，care burdens and son preference．

Fertility in China dropped below the replacement level in the early 1990s, and has been increasingly lower, arousing intense academic discussion on fertility policy adjustment．This paper estimates the size of objective population that is targeted by the two-child policy after computing the amount of the only children in 2012 based on the data of the 2005 national 1% population sampling survey, and analyzes its impact on number of annual births．The results show that on account of the large number of the objective population covered by the two-child policy and women's strong desire to have the second
child，if there was an immediate transition to a universal two-child policy, number of annual births would sharply increase with the peak value up to nearly 50 million and a total fertility rate of about 4.5．However, immediately implementing the two-child policy could significantly retard the negative growth trend of population in the future, increase labor supply and slow down population aging in China．

The Low Fertility Trap Hypothesis proposes that there are three self-reinforcing mechanisms—demographic，sociological and economic，working towards a downward spiral in future fertility. Once TFR drops below 1. 5，it will be difficult to recover. The fertility recovery emerging in many countries across the world has challenged the low-fertility trap theory and also the justification of the theory itself. So low-fertility trap is more likely a pattern summarized from a short-time phenomenon than a generalized social law. As with China，the current fertility level is above 1. 5 births per woman，and China is not in the“Low-fertility trap”. Moreover most recent surveys suggest that current fertility intention in China is above 1. 8 births per woman and more than 60 percent of people would have a second child if there is an adjustment of fertility policy. In addition，birth postponement is still playing an import role in reducing TFR in China. Thus，with the high fertility intention，adjustment of family planning policy and decreasing tempo effect，TFR in China will experience upturn but not further decline in the near future.It is lack of evidence to conclude that China has already been or is going to be trapped in low fertility.