Are the total fertility rates of men and women different at below-replacement levels?An answer obtained from the G7 countries

A child is born to a father and a mother.This fact,however,is yet to be recognized by demography,in which fertility refers to women’s natural ability to give birth.The main reason for the absence of men is that data on births are more often available for women than for men.But in the last few decades,data availability has greatly improved.Recent studies show that total fertility rates(TFRs)of men can be calculated for most countries in the world and that the difference between the TFRs of men and women can be quite large.For low-fertility countries,nonetheless,these studies show little difference between the TFRs of men and women,giving rise to the question:Is men’s fertility worth further investigation?To avoid ambiguity in describing a particular difference as small or big,this paper provides a formula for probabilistic TFRs.Using hypothesis test on probabilistic TFRs,we can say that the difference between the TFRs of men and women is statistically significant for all the G7 countries,except for France.To explain the differences between the TFRs of men and women,this study uses models of stable populations and concludes that the one-sex stable population models cannot explain the results whereas a two-sex joint stable population model can do so.By using the two-sex population model,we can explain why the TFR of men in France is almost the same as that of women,and why it is lower than that of women in the other six G7 countries.More specifically,by using the model,we can help explain 76%of the variance in the difference between the TFRs of men and women.Future studies may be able to show that men’s TFR is significantly lower than women’s in other countries too and explain why it is so.The above findings,however,require closer attention and further investigation,because low fertility could lead to socioeconomic problems.Beyond TFRs,extending fertility studies from women to men as well,that is,conducting fertility studies on both women and men,will fundamentally improve our knowledge about fertility age patterns,trends,determinants,policies and other related issues.

Fair Plan 9: Engineering Human Population to Help Safeguard Earth’s Climate

Our Fair Plan to Safeguard Earth’s Climate reduces the emission of greenhouse gases to zero over the 80-year time period 2020 to 2100. To accomplish this, humanity must reduce its carbon intensity—the amount of CO2 emitted per unit of energy—and its energy intensity—the amount of energy needed to generate a unit of Gross World Product. As shown in our Fair Plan 8 paper, reducing the future growth of the human population can also contribute to the reduction in greenhouse-gas emissions. Here, we explore this further. We project the historical decrease in Total Fertility Rate (TFR) across the 21st century toward its logistical asymptotic Reference value of 2.04 Births Per Woman (BPW). We then engineer the asymptotic TFR beginning in 2020 to 1.95, 1.85, 1.75, 1.65 & 1.55 BPW. We project the population across the 21st century for the Reference and engineered TFRs. We do so using the results of Basten, Lutz and Scherbov (2013) for the population evolution across the 21st century for 8 constant TFR values (=2.50, 2.25, 2.00, 1.75, 1.50, 1.25, 1.00 & 0.75 BPW). We find that purposefully engineering the asymptotic TFR can significantly contribute to achieving the reduction in greenhouse-gas emissions needed to transition to our Fair Plan to Safeguard Earth’s Climate.

China fertility report,2006-2016 An analysis based on China fertility survey 2017

Based on China fertility survey 2017,this report presents the national fertility level,age-specific fertility rate and parity distribution.The survey results show that during 2006-2016 the mean ages at first marriage and first birth increased by 2.7 and 2.6 years respectively.From 2006 to 2011,the total fertility rate was around 1.60-1.70,and experienced notable fluctuations during 2012-2016.Compared the age-specific fertility in 2006 with in 2011,the curve in 2016 shifted significantly to the right side.Affected by the relaxation of the fertility policy,the proportion of second births among the total births had increased year by year since 2012.

Drastic changes in fertility level and timing in response to marriage and fertility policies: evidence from Shandong province, China

China’s“one-child policy”that had been in force between 1980 and 2016 evolved over time and differed widely between regions.Local policies in many regions also targeted the timing and spacing of childbearing by setting the minimum age at mar-riage,first birth and second birth and defining minimum interval between births.Our study uses data from the 120 Counties Population Dynamics Monitoring Sys-tem to reconstruct fertility level and timing in nine counties in Shandong province,which experienced frequent changes in birth and marriage policies.We reconstruct detailed indicators of fertility by birth order in 1986-2016,when policies on mar-riage and fertility timing became strictly enforced since 1989 and subsequently relaxed(especially in 2002)and abandoned(in 2013).Our analysis reveals that birth timing policies have fuelled drastic changes in fertility level,timing and spacing in the province.In the early 1990s period fertility rates plummeted to extreme low levels,with the provincial average total fertility rate falling below 1 in 1992-1995.Second births rates fell especially sharply.The age schedule of childbearing shifted to later ages and births became strongly concentrated just above the minimum pol-icy age at first and second birth,resulting in a bimodal distribution of fertility with peaks at ages 25 and 32.Conversely,the abandonment of the province-level policy on the minimum age at marriage and first birth and less strict enforcement of the policy on the minimum age at second birth contributed to a recovery of period fertil-ity rates in the 2000s and a shift to earlier timing of first and second births.It also led to a shorter second birth interval and a re-emergence of a regular age schedule of fertility with a single peak around age 28.

Declining number of births in China: a decomposition analysis

Recent drastic changes in marriage and fertility behaviour have a considerable impact on China’s annual number of births.Population momentum and changing fertility policy largely determine the changing number of births in China over the past two decades.While the annual number of births have been steadily fluctuat-ing around 16-18 million,contrary trends in the number of the first births and the second births have been observed.The two-child policy produced marked effects on the rising number of the second births,which is however to a large extent offset by the declining number of the first births resulting from rapidly postponing age at first marriage.A decomposition analysis demonstrates that all demographic factors are depressing birth numbers,including the size of reproductive-age women and its age structure,proportion married and marital fertility in the very recent years.China’s seventh population census conducted in 2020 suggests a more rapid decline in birth numbers,marking the start of a lowest-low fertility in Chinese history.

The Age Distribution Model and the Parity Progressive Model of Population and Their Equivalence

This paper proved that the integral form and the integro-differential form of the age-structured population equation (Lotka model) are equivalent, the integral form and the integro-differential form of the parity progressive population equation (Henry model) are equivalent. By the age parity progressive model, the equivalence between Lotka model and Henry Model is also proved. Moreover, the relation between the parity progression ratio and the total fertility rate is given.