| The population problem is a key factor affecting the sustainable economic and social development of a country or region.Since 1970,more and more countries in the world have successively completed demographic transitions,and fertility rates have rapidly declined.By the1990 s,the fertility rate in the world had converged faster than other socio-economic variables.Although the world fertility rate continues to decline globally,there is significant spatial differentiation in the direction and magnitude of change.High-fertility areas in the world are further concentrated in sub-Saharan Africa,and low-fertility areas spread mainly in Europe.The areas include Asia,Latin America and the Caribbean,where the fertility is changing in this world.In this context,the path of fertility evolution in the world's high or low fertility regions and the related factors affecting fertility changes have become the focus of domestic and foreign scholars.Therefore,it is of great theoretical and practical significance to discuss the pattern of spatial differentiation of fertility changes in the world.It is important to grasp the current status and trends of fertility changes in the world and to improve the adjustment of China's fertility policy.This paper takes the spatial differentiation of changes in fertility rates from 1990 to 2015 as the research object,and uses theories and methods of population geography,population economics,regional economics,and econometrics as guidance,and uses the United Nations and the United States Population Advisory Service.Statistical data on fertility,population development,and socio-economic development by agencies such as the World Bank,OECD.The author wanted to explore the characteristics and laws of spatial variation in the world fertility rate,factors and mechanisms,and policy evolution.The paper is proposed to provide decision-making basis in China,which is at the crossroads of fertility policy adjustments.The full text is divided into six parts:The first part is an introduction,which summarizes the background,theoretical and practical significance of the topic.It analyzes relevant studies between domestic and abroad and gives a review.It elaborates the research ideas,contents,research methods,and technical routes of the thesis.The second part is an outline of the theory.First of all,it elaborates the related concepts and connotations of general fertility rate,total fertility rate and fertility model.Then,it sorts out demographic theories affecting fertility changes,including marginal children's rational choice theory,child quality substitution theory,the supply-demand theory of fertility decisions and the intermediary variable theory of fertility.The third part is based on the World Bank database,the United States Population AdvisoryService,the United Nations database and other multivariate data.Firstly,fertility indicators such as total fertility rate,average childbearing age,age-specific fertility rate,and adolescent fertility rate are selected to qualitatively analyze fertility levels on a global scale.Then it used the standard deviation ellipse,the global spatial autocorrelation and natural fracture point method to quantitatively characterize the spatial differentiation characteristics and laws of the world fertility changes.The main conclusions are as follows:(1)Fertility levels at the global scale mainly exhibited the following characteristics: Fertility levels in most countries or regions showed a declining trend;Countries with extreme fertility levels showed significant changes;Age for average childbirth advanced;Birth patterns existed large differences;Adolescent birth rates were showing a downward trend.(2)This part uses the standard deviation ellipse and the barycenter migration trajectory to reveal the global spatial pattern of global fertility change.From 1990 to 2015,the centers of gravity were all located in the southwestern part of Chad in Africa.The overall change in the center of gravity was relatively small and shifted from the southwest to the north.It shapes "V".The speed and trajectory of the center of gravity migration show a phased feature.It diffused and gathered in the main direction.(3)The part uses the global spatial autocorrelation analysis to reveal the spatial correlation pattern of global fertility changes.It has been found that countries with similar fertility levels tend to agglomerate since the 1990 s.The spatial agglomeration trend is obvious.(4)This part uses the natural fracture method to analyze the evolution of the global fertility change.The number of countries with ultra-low birth rates increased from 1990 to 2015.The distribution area was scattered from Western Europe,Eastern Europe and South Asia to all sub-regions in Europe and Asia.The low-fertility countries spread over the region from Europe,Southeast Asia to West Asia,North America and Latin America;The medium-fertility countries are mainly distributed in Africa,Asia,and Latin America;The high-fertility countries are distributed in sub-Saharan Africa.Secondly,at the geographical subregional scale,the use of local spatial autocorrelation analysis the hotspots of fertility evolution in various geographical subregions in continents such as Africa,the Americas,Asia,Europe,and Oceania from 1990 to 2015.The paper explored the direction and magnitude of fertility spatial transfer.The main conclusions are as follows: The high-high type areas of Africa from 1990 to 2015 are mainly distributed in sub-Saharan Africa and the central part of the African continent.It includes Central Asia,East Africa,West Africa and other sub-regions.The low-low type areas are mainly distributed in Northwest Africa,North Africa;The high-high type areas of the America are mainly distributed in Central America and South America.The low-low type areas are mainly distributed in the Caribbean;The high-high areas of Asia are distributed in south-central Asia,it includes South and Central Asia.Thelow-low type areas are concentrated in East Asia;The high-high type areas of Europe were not significant before 2000.The Nordic region become into hot spots after 2000 due to the implementation of encouraging family policies.The low-low areas are mainly distributed in countries such as Western Europe and Southern Europe;The high-high type areas of Oceania are mainly distributed in the island countries in the northeast of Oceania.It mainly includes Australia and New Zealand.Finally,based on the national scale,the countries in the world are divided into four categories.It includes ultra-low,low,medium and high fertility.The nuclear density analysis method is used to analyze the magnitude and direction of changes in fertility in order to judge whether fertility convergence exists.The part reveals the direction and speed of change in fertility rates in low-fertility and high-fertility countries.The main conclusions are as follows:(1)The ultra-low fertility countries appears to be non-equilibrium distribution of bipolarity weakly.Then it becomes the distribution of convergence equilibrium.And it becomes to distribution of polarization disequilibrium;The low-fertility countries show an unbalanced development trend from polarized to multipolarity;The middle-fertility countries have experienced an evolutionary process from the convergence of equalization to the disequilibrium of polarization.Then it becomes to equalization;high-fertility countries have converged to lower fertility levels;(2)The fertility transition in countries with low fertility levels vary greatly in time and speed.The Fertility transitions process in West Asia and Latin America and the Caribbean have been more rapid.Fertility rates in most countries have rebounded after falling to their lowest levels.Most of the fertility rate in high-fertility country has entered the stage of fertility change before 1994,and there is a big difference in the rate of decline.High fertility countries with a rapid decline in fertility rate are mainly concentrated in Asia,Latin America and the Caribbean,South Africa and Oceania.In the fourth part,firstly,we compare and analyze the core influence variables in nature,demographics,economics,society and policy,which is affecting the changes in fertility in different types of countries.Secondly,the paper used scatter plots to analyze income,mortality,average years of education,the degree of influence of urbanization rate and women's labor participation rate on fertility variables in high fertility,medium fertility and low fertility type countries.Finally,using demographic models such as panel error data model(PECM)and dynamic panel data model to simulate the influence of multi-factor interactions in different types of countries in the world and to explain the mechanism of the effects of various factors on fertility changes in different types of countries.The main conclusions are:(1)Panel error correction models study four co-integration relationships.It includes total fertility,mortality andper capita GDP,total fertility,mortality and average years of schooling,total fertility,mortality and urbanization,total fertility,mortality and labor participation rate of women.There is an error correction mechanism,that is,there is a long-term relationship in the change process.(2)The dynamic panel data model shows that in the low fertility group,the first-order lags of the total fertility rate,the urbanization rate and the labor participation rate of women have the greatest influence on the total fertility rate.And the policy factors have the smallest impact.The low-fertility countries need to strengthen the effectiveness of the fertility policy;In the middle-fertility countries,the first-order lags of the total fertility rate,urbanization and mortality have the greatest influence.The average number of years of education have the least impact;In the high-fertility countries,the first-order lags in total fertility,mortality and women's labor force participation have the greatest impact on fertility changes.Per capita GDP has no impact.And the mortality of the sub-Saharan Africa's regions are high due to AIDS,malaria and other infectious diseases.Mortality phenomenon should arouse extensive attention.In the fifth part,we firstly describe the evolutionary process and characteristics of birth control policies in countries such as India,Japan,Korea,Taiwan,and Singapore.Secondly,we outline the process of adjustment and evolution of China's birth control policy and evaluate the policy effects of relevant stages.Finally,it proposes three possible paths for the adjustment of China's fertility policy and makes initial judgments on the path of adjustment,and China Should Adopt a Fertility Policy to Encourage Second Child Comprehensively in the future.The sixth part summarizes the main conclusions of the paper and explains the Suggestions... |
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