The pattern of changing trends and the regional differences in the sex ratio at birth: evidence from Korea and Jilin Province,China

"The main purpose of this study is to develop explanations for the pattern of recently changing trends and regional differences in the sex ratio at birth in Korea and for Koreans in Jilin Province and Yanbian Autonomous Prefecture, China.... The findings suggest that, since the mid-1980s, sex ratios at birth have risen remarkably in Korea.... This paper also highlights the recent increase in the sex ratio at birth for the Korean population in China, residing in urban areas densely populated with Koreans. As the key forces behind the regional differences in sex ratios at birth, the effects of son-selective reproductive behaviors, which in turn, are affected by the community characteristics, are stressed."     

The number of illegal migrants of Mexican origin in the United States: Sex ratio-based estimates for 1980

This article reports the results of applying a sex ratio-based method to estimate the number of undocumented Mexicans residing in the United States in 1980. The approach centers on a comparison between the hypothetical sex ratio one would expect to find in Mexico in the absence of emigration to the United States and the sex ratio that is in fact reported in preliminary results from the 1980 Mexican Census. The procedure involves, inter alia, assuming a range of values for the sex ratio at birth and for census coverage differentials by sex in Mexico. Even the combinations of these values most likely to result in large estimates suggest that no more than 4 million illegal migrants of Mexican origin were residing in the United States in 1980.     

Utilization of Infertility Treatments: The Effects of Insurance Mandates

Over the last several decades, both delay of childbearing and fertility problems have become increasingly common among women in developed countries. At the same time, technological changes have made many more options available to individuals experiencing fertility problems. However, these technologies are expensive, and only 25% of health insurance plans in the United States cover infertility treatment. As a result of these high costs, legislation has been passed in 15 states that mandates insurance coverage of infertility treatment in private insurance plans. In this article, we examine whether mandated insurance coverage for infertility treatment affects utilization. We allow utilization effects to differ by age and education, since previous research suggests that older, more-educated women should be more likely to be directly affected by the mandates than younger women and less-educated women, both because they are at higher risk of fertility problems and because they are more likely to have private health insurance, which is subject to the mandate. We find robust evidence that the mandates do have a significant effect on utilization for older, more-educated women that is larger than the effects found for other groups. These effects are largest for the use of ovulation-inducing drugs and artificial insemination.     

Falling Short of Highest Life Expectancy: How Many Americans Might Have Been Alive in the Twentieth Century?

Life expectancy at birth in the United States during the twentieth century was lower than in many other highly developed countries. We investigate how this mortality disadvantage in the last 100 years translates into the number of hypothetical lives lost and their sex and age structure. We estimate the hypothetical US population if it had experienced in each decade since 1900 the mortality level of the country with the then highest life expectancy and compare the results to the actual figures in 2000. By 2000, the number of additional people who could have been alive had the mortality levels in the United States been as low as those in countries with the highest life expectancy was 66 million. This number is distributed equally between males and females. Suboptimal mortality at reproductive ages is crucial for the cumulative effect of potential lives lost, resulting from premature deaths of women who could still become first‐time mothers or bear additional children. Out of the 66 million additional persons who could have been alive in 2000, 45 million are attributable to those indirect deaths. Although the differences in the composition of the population by sex and age under the two mortality regimes are minor, the majority of people who might have been alive—54 million—were of working age or younger.     

Parental age and offspring mortality: Negative effects of reproductive ageing may be counterbalanced by secular increases in longevity

As parental ages at birth continue to rise, concerns about the effects of fertility postponement on offspring are increasing. Due to reproductive ageing, advanced parental ages have been associated with negative health outcomes for offspring, including decreased longevity. The literature, however, has neglected to examine the potential benefits of being born at a later date. Secular declines in mortality mean that later birth cohorts are living longer. We analyse mortality over ages 30–74 among 1.9 million Swedish men and women born 1938–60, and use a sibling comparison design that accounts for all time-invariant factors shared by the siblings. When incorporating cohort improvements in mortality, we find that those born to older mothers do not suffer any significant mortality disadvantage, and that those born to older fathers have lower mortality. These findings are likely to be explained by secular declines in mortality counterbalancing the negative effects of reproductive ageing.     

基于空间数据的出生性别比偏高影响因素研究

以出生性别比升高机理为基础,应用空间计量技术分析2000年份地市横截面数据和地理空间数据,实证研究各因素对出生性别比偏高的影响。结果表明:社会经济文化因素通过影响生育决策和生育行为进而引起出生性别比偏高,影响出生性别比升高的各因素存在空间相互作用,其空间自相关属于高高-低低类型;传统文化、公共政策、城镇化水平以及良好的社会法制环境将抑制出生性别比升高;经济发展水平、家庭收入、受教育程度和医疗发展水平将促使出生性别比升高;生育政策对出生性别比升高的影响不具有统计显著性。     

The fortunes of one's birth: Relative cohort size and the youth labor market in the United States

Using two different measures of relative cohort size – one indicating the size and placement of an individual's own birth cohort, and the other, the ratio of young to prime age adults in the United States in that year – it has been possible to isolate strong effects of the population age structure on wages in the United States over the past thirty-three years. These effects have been strong enough that virtually all of the observed change in the experience premium, and a substantial proportion of the changes in the college wage premium, can be explained by the relative cohort size variables alone. Even changes in the amount of within-group variance in wages appear to be largely a function of changing age structure, and absolute wage levels have been strongly affected by these demographic changes, suggesting that population growth can have positive effects on the economy. Received: 27 January 1998/Accepted: 6 June 1998     

Redefining procreation: facing the issues

It is now possible for a child to have up to 5 individuals claiming to be parents: a sperm donor, an egg or ovum donor, the woman providing a womb for gestation, and the couple raising the child. Technology has provided 3 techniques of conception: artificial insemination, in vitro fertilization and embryo transfer, and surrogate motherhood. There is increased concern with infertility in the US and decreased availability of children for adoption. New reproductive technologies share, with the recent profound changes in the American family and more relaxed attitudes towards sexuality, a common potential to alter family structure and family dynamics. Certain issues are germane to all birth technologies such as whether such technologies should exist at all, whether there is a right to procreate, what criteria should govern access to these technologies, and how they should be regulated. Complex ethical, legal, social and moral questions are involved. Advances in reproductive technologies have created a gap between science and public policy. The articulation of guiding principles is essential to narrow that gap.     

Age distribution and the stable equivalent

Some populations, like that of the United States in the 1950's, have a smaller proportion of women of reproductive age than they would ultimately attain with continuance of their age-specific birth and deaths rates, a continuance which produces the condition known in demography as stability. Others, like that of the United States in the 1930's, have relatively more women of reproductive age than they would ultimately attain with stability. A way of studying ages is to calculate how many women of stable age distribution would be equivalent from the viewpoint of reproduction to the women observed. This stable equivalent was 69,535,000 or 16 percent below the observed United States female population in 1955, and 12 percent above the observed in 1935. The stable equivalent is a measure of fertility potential, closely related to R. A. Fisher's reproductive value. Calculations for four countries illustrate how a fall of the birth rate, for example in demographic transition, occasions an age distribution in which the stable equivalent is greater than the observed number of women. The notion of stable equivalent is useful for comparison because changes in it are nearly invariant with respect to the age-pattern of fertility used. The statement that the United States stable equivalent increased by 11 percent between 1960 and 1965 holds irrespective of whether the 1960 or the 1965 age-specific fertility and mortality rates are used as standard.     

Do Daughters Really Cause Divorce? Stress,Pregnancy, and Family Composition

Provocative studies have reported that in the United States, marriages producing firstborn daughters are more likely to divorce than those producing firstborn sons. The findings have been interpreted as contemporary evidence of fathers’ son preference. Our study explores the potential role of another set of dynamics that may drive these patterns: namely, selection into live birth. Epidemiological evidence indicates that the characteristic female survival advantage may begin before birth. If stress accompanying unstable marriages has biological effects on fecundity, a female survival advantage could generate an association between stability and the sex composition of offspring. Combining regression and simulation techniques to analyze real-world data, we ask, How much of the observed association between sex of the firstborn child and risk of divorce could plausibly be accounted for by the joint effects of female survival advantage and reduced fecundity associated with unstable marriage? Using data from the National Longitudinal Survey of Youth (NLSY79), we find that relationship conflict predicts the sex of children born after conflict was measured; conflict also predicts subsequent divorce. Conservative specification of parameters linking pregnancy characteristics, selection into live birth, and divorce are sufficient to generate a selection-driven association between offspring sex and divorce, which is consequential in magnitude. Our findings illustrate the value of demographic accounting of processes which occur before birth—a period when many outcomes of central interest in the population sciences begin to take shape.     

Registration completeness and international comparisons of infant mortality

The physical development of the live born infant is the single most important variable governing its survival: infant mortality among those weighing 2,500 grams (5 1/2 pounds) or less at birth is 17 times the mortality among those weighing more than 2,500 grams at birth. The variation in mortality according to birth weight (or gestation) is greater than for subclasses of color, sex, maternal age, or birth order. Infant mortality in the United States is significantly higher than in a number of other countries e.g., Sweden, Netherlands, Norway. The difference is thought, by some, to be due to underregistration of low birth weight infants in other countries. In this paper, distributions of live births by birth weight for Denmark, England and Wales, New Zealand, and the United States, and infant mortality data for Denmark and the United States are examined. The data do not support a hypothesis of gross underregistration of live born infants in other countries. The results indicate that some index of physical development (birth weight, gestation, or a combination of both) should be included in any appraisal of infant mortality.     

Women’s sex preferences in the United States: 1970 to 1975

This analysis examines the potential effect of sex preselection technology in the United States. The results suggest that controlling the sex of offspring is not the desire of most American women; that if it were employed, there would be a significant increase in sons as first-born and daughters as second children; that the overall sex ratio would be little changed from that occurring naturally except at very low fertility levels with universal use of such technology; and that fertility is only minimally influenced by gender preferences.     

Regional—sub-cultural explanations of black fertility in the United States

This paper re-examines the relevance of the hypothesis concerning the Southern sub-culture and black fertility in the United States. According to zero-order correlation analysis, Southern-born blacks show higher fertility than those born in other regions. But a dummy-variable regression technique applied to the data from the 1970 public-use sample indicates that the Southern origin — independent of other factors-is not different from other regions. Southern birth has the effect of increasing black fertility, but much less so than birth in the North Central region. Southern blacks show higher fertility because of their lower socio-economic background. It is concluded that geographical regions in the United States have little or no cultural meaning in explaining reproductive behaviour.     

Regional-sub-cultural explanations of black fertility in the United States

Summary This paper re-examines the relevance of the hypothesis concerning the Southern sub-culture and black fertility in the United States. According to zero-order correlation analysis, Southern-born blacks show higher fertility than those born in other regions. But a dummy-variable regression technique applied to the data from the 1970 public-use sample indicates that the Southern origin - independent of other factors-is not different from other regions. Southern birth has the effect of increasing black fertility, but much less so than birth in the North Central region. Southern blacks show higher fertility because of their lower socio-economic background. It is concluded that geographical regions in the United States have little or no cultural meaning in explaining reproductive behaviour.     

中国乡城人口流动与城镇出生人口性别比——基于“五普”数据的分析

本文利用中国第五次人口普查1‰抽样数据,以城镇区域人口为重点,定量分析了农村人口流动对城镇地区人口出生性别比,以及农村流入城镇人口子女性别的影响。研究发现,中国农村未流动人口、农村流入城镇人口和城镇非农村流入人口的出生性别比均偏离了出生性别比的正常水平,农村人口流动影响了城镇地区生育性别,农村流入城镇人口相对较强的男孩偏好观念加剧了城镇地区出生性别比偏高。     

The Decline of Son Preference in South Korea: The Roles of Development and Public Policy

For years, sex ratios at birth kept rising in South Korea despite rapid development. We show that this was not an anomaly: underlying son preference fell with development, but the effect of son preference on sex ratios at birth rose until the mid‐1990s as a result of improved sex‐selection technology. Now South Korea leads Asia with a declining sex ratio at birth. We explore how son preference was affected by development and by public policy. Decomposition analysis indicates that development reduced son preference primarily through triggering normative changes across society—rather than just in individuals whose socioeconomic circumstances had changed. The cultural underpinnings of son preference in preindustrial Korea were unraveled by industrialization and urbanization even as public policies sought to uphold the patriarchal family system. Our results suggest that child sex ratios in China and India may decline before those countries reach South Korean levels of development, since the governments of both countries vigorously promote normative change to reduce son preference.     

Maybe Next Month? Temperature Shocks and Dynamic Adjustments in Birth Rates

We estimate the effects of temperature shocks on birth rates in the United States between 1931 and 2010. We find that days with a mean temperature above 80°F cause a large decline in birth rates 8 to 10 months later. Unlike prior studies, we demonstrate that the initial decline is followed by a partial rebound in births over the next few months, implying that populations mitigate some of the fertility cost by shifting conception month. This shift helps explain the observed peak in late-summer births in the United States. We also present new evidence that hot weather most likely harms fertility via reproductive health as opposed to sexual activity. Historical evidence suggests that air conditioning could be used to substantially offset the fertility costs of high temperatures.     

The Implementation of Preferences for Male Offspring

Over the past quarter century the sex ratio at birth (SRB) has risen above natural levels in a number of countries, mostly in Asia. This rise has been made possible in populations with strong son preference by the increasing availability of safe, effective, and inexpensive technologies to determine the sex of a fetus and to end unwanted pregnancies. This article documents levels and trends in the sex ratio at birth, in preferences for male offspring (using information on desired number of girls and boys), and in the implementation of these preferences. DHS surveys from 61 countries in Africa, Asia, and Latin America and for Indian states are the main source of data. A comparison of desired with actual SRBs finds large gaps in most populations, implying a substantial pent‐up demand for male offspring and the technology to implement this preference. Two types of actions to implement preferences are considered: the practice of contraception to stop childbearing after the desired number of sons has been born and the use of sex‐selective abortion to avoid female births. The second part of the article discusses factors that could influence the SRB, including the promotion of gender equality, and the implications of these factors for future trends.     

出生人口性别比周期性波动研究——兼论中国出生人口性别比的变化趋势

在观察数据基础上,描述出生人口性别比周期性波动现象,并对其内在机理做出解释。研究发现,出生人口性别比的周期性波动是一个普遍规律,其波动周期与生育间隔相关。正常情况下,周期成分对出生人口性别比的变化影响较小并且稳定。中国出生人口性别比的周期成分明显大于其他国家,这与中国强烈的性别偏好有关。周期成分不是影响中国出生人口性别比的主要因素,性别选择行为是出生人口性别比失衡的主要原因。在实际工作中应该尊重出生人口性别比周期性波动的客观规律,关注出生人口性别比的中长期变化趋势。中国出生人口性别比的"拐点"已经出现,在继续加强综合治理工作的条件下,出生人口性别比将进入下降过程。     

Child-spacing differentials for white and non-white couples according to educational level of attainment for the 1/1000 sample of the United States population in 1960

Abstract Despite previous research on the relationship between husband's or wife's level of educational attainment and childbearing and child spacing, relatively few data exist on couples' combined educational attainment which compares whites and non-whites. Further, to date a systematic exploration of available information contained on the 1/1,000 sample of the United States population in 1960 has not been undertaken. This paper utilizes these data and investigates the time intervals between marriage and first birth and between subsequent events to determine what relationships exist between parity and child spacing for white and non-white couples by level of educational attainment.