A three-group age structure can be designated as a point in the triangular diagram, while the routine of the points in time series traces the age structure evolution. The paper classifies the age structure evolution patterns of countries (areas) in the world and provinces in China, and discovers the general and ergodic age structure transition (AST) pattern which experiences three stages: the “bonus raising” stage (i.e., from the traditional fertile young population to fewer children-more labors population), the “debted ageing” stage (i.e., from fewer children-more labors population to fewer labors-more aged population), and the stage in between (i.e., turning stage). While developed countries are primarily in the middle of stage three, most developing countries are in the late phase of the first stage, and many least developed countries in Africa are still in the early stage one or even in the traditional position. Started in the 1950s and accelerated since the 1980s, the AST in China is now just passing the turning stage with diversifying decreasing bonuses at turning points from coast to inland provinces. According to a simulation scenario, China will approach the equilibrium position near 2100, with 15% children, 55% labor forces, and 30% older people, which is probably the common end of all countries in the future.

This paper constructs an explanatory model of fertility changes based on social dynamics, which consists of three factors affecting human reproductive behavior, including fertility intentions, contraceptive barriers and competing preferences. The changes in the relative effects among these three factors contribute to three stages of fertility change in human history: natural fertility, shrinking fertility and suppressed fertility. In China, family planning policy is the fourth factor. With the promotion, implementation and relaxation of the family planning policy, Chinese reproductive behaviors have adjusted accordingly, leading to fluctuating fertility rates. The building-up of market economy in early 1990s stimulated the competing preferences. Based on data for East China from the 2017 fertility survey, this paper examines trends in total fertility rate, marital duration-specific fertility rate and parity-specific total fertility rate. With Shanghai in center, fertilities by provinces differ latitudinally. We also show the changes of monthly distribution of births since 2012 to see the influence of family planning policy adjustment.

In the process of reform on China’s household registration system after 1978,local governments have gradually taken the role of the central government,becoming the main driving forces of the reform.They have shaped the new trend of the reform by adopting different policies for different households.Examining local reform practices is,therefore,important for further relevant reforms.By sorting a large amount of laws and regulations issued by local governments about the reform on household registration system,and highlighting four policies(namely,temporary residence certificate system,blue seal household register,reform on household registration system of towns,and talents residential certificate system),this paper analyzes the temporal and spatial evolutive trajectory and rules,from the perspective of diffusion,explores the proliferation laws,and provides policy implications.

Under-reporting rate of China’s 2000 population census stood at 1.81%,indicating deterioration of demographic data quality in China.On the one hand,this rate is an objective representation of current data quality;on the other hand,China’s population data quality is good as compared to other countries.Causes for under-reporting are many-sided,including design of census plan,people’s cooperation,funds input,administrative examination etc.As for the coming 6th national population census,we need to seriously analyze the causes of under-reporting,so that we can take appropriate measures to improve census data quality.