Research On Female Reproductive Cycle Transition During The Second Demographic Transition: Group Differences And Regional Patterns

The classic theory on the development and evolution of the population is the Demographic Transition.Whether it is the First Demographic Transition or the Second Demographic Transition(SDT),the focus of attention is on the law of fertility change.However,population development and change have never been a univariate process.Changes in birth and death patterns and total population growth are bound to be accompanied by corresponding changes in population age structure,gender structure,and timing of childbearing.Scholars have conducted in-depth research and theoretical summaries on the transition of age structure and sex ratio at birth,but the academic circles have not yet fully studied the general pattern and evolution law of birth time rhythm or birth history.This paper takes the SDT as the theoretical and realistic background,focuses on the time course of childbearing,and constructs the Reproductive Cycle Transition(RCT for short)by analyzing the age at first birth,age of last birth,and the reproductive span,and seeks its echo with the theory of Demographic Transition.The study of the RCT helps to explore the endogenous mechanism of Demographic Transition from the perspective of fertility history,and at the same time injects new ideas and provides new evidence for the women’s liberation movement in reproductive behavior.First of all,based on the United Nations fertility data,the four fertility evolution patterns in Europe and America,Asia-Africa-Latin America,Sub-Saharan Africa,and East Asia are displayed with their own characteristic trajectory,and China’s position in the world coordinate system is determined;secondly,using China’s population census data to analyze the changing trends of the five indicators of total fertility rate(TFR),mean age at first marriage,divorce rate,lifelong unmarried rate and fertility pattern,and evaluate the overall progress and regional disparities of China’s SDT;thirdly,using the China Fertility Survey to find out the period changes,group differences and influencing factors of age of first birth,age of last birth and reproductive span,and thus to identify the characteristics of the RCT in China;fourthly,classification sorting out the changing laws of the RCT in various countries or regions in the world,deriving a universal model of the RCT;finally,referring to the Engel Coefficient in the field of economics,a new concept of "Childbearing Engel Coefficient" is proposed,which can be used to measure the change of women’s time allocation and scale the process of RCT.The study has the following important conclusions:First,China’s fertility transition is “quick,hard and steady”,that is,it takes a short time,has a large range,and is stable at a low level for a long time.In 2021,the TFR is astonishingly low at 1.18,ranking the 10 th lowest among all countries(regions)in the world.Second,China is undergoing an SDT with "special characteristics" and showing regional differences.The eastern municipalities directly under the Central Government are the forerunners of the SDT,and the Northeast is the follower after Beijing,Tianjin,and Shanghai,while in other regions the development is relatively slow.Among them,the process of the eastern provinces,the central region,and the northwest is similar,and they are all in the initial stage of the SDT.The southwest region lags behind the most,and it can be said that it has just entered the SDT.Third,under the two-way squeeze of the age of first birth and age of last birth,Chinese women’s reproductive span has been reduced from 16 years in 1950 to about 4years in 2020,and the "Childbearing Engel’s Coefficient" has also dropped from a high value of 26% to less than 5%.Fourth,China’s RCT shows group differences.This study shows longer reproductive spans to be associated with ethnic minority population,low levels of women’s education,low family income,high parity,rural residence,central regions,and western regions.Effects are statistically significant.Fifth,When the TFR is higher than the replacement fertility,the main influencing factor of age at last birth is the TFR,when the TFR falls below replacement level,age at first birth and birth interval together or alternately become the main influencing factors of age at last birth;taking 1995 as the boundary,TFR,and birth interval alternately become the main influencing factors of the reproductive span.Sixth,the RCT has shown sufficient "Ergodicity",and the reproductive cycle will change from the "low-high-high" type with low age at first birth,high age at last birth,and high reproductive span to the "high-low-low" type with high age at first birth,low age at last birth and low reproductive span.It can be specifically divided into four stages.In the first stage,the age at first birth is low for a long time,and the age at last birth and reproductive span is stable and high for a long time;in the second stage,the age at first birth rises slowly,the age at last birth drops sharply,and the reproductive span gradually shortens;in the third stage,the age at first birth rises rapidly,the age at last birth continues to rise,and the reproductive span is stable at the low level;the age at first birth in the fourth stage remains high and stable for a long time,and the age at the last birth and the reproductive span remain low and stable for a long time.There is a close correspondence between the RCT and the Demographic Transition.It can be considered that the RCT echoes the Demographic Transition.Seventh,the global RCT shows differences in socioeconomic levels and regional differences.The developed,less developed,and least developed countries(regions)started the RCT in the late 1800 s,the 1960 s,and the 1980 s,respectively,with a phase difference of 60 and 20 years before and after;corresponding to the regional patterns of fertility transition,the RCT can also be aggregated into four patterns: Europe and America,Asia-Africa-Latin America,Sub-Saharan Africa,and East Asia.Among them,Europe and America are the forerunners of the RCT,Asia-Africa-Latin America is the followers,Sub-Saharan Africa is the laggard,and East Asia is a special type of leapfrog.Eighth,the "Childbearing Engel Coefficient" in the world has been decreasing and the lower limit is basically around 4%.Women’s time allocation is gradually shifting from single childbearing and child-rearing to receiving higher education and pursuing higher socioeconomic status,devoting more energy to their own development and value realization,with more diversified time allocation,but the reality of lowest-low fertility behind deserves attention.