中国双生子出生性别比研究

人口自然出生性别比是分析和评价人口出生性别比偏离的重要指标,中国对人口自然出生性别比的研究一直比较缺乏。人的出生性别比正常范围为102～107,国内一般都是以其上限作为标准判断人口出生性别比偏高的程度。但是这种做法是值得商榷的。利用第四次全国人口普查资料中的双生子信息探讨双生子出生性别比特征。研究表明,中国1989年双生子出生性别比为104.87,在女性主要生育年龄阶段生育的双生子出生性别比是相当稳定的,比较接近自然状态下的出生性别比。相比较而言,中国人口出生性别比不仅普遍偏高,而且随女性生育年龄变化的模式也不相同。     

中国出生性别比水平与数据质量研究

通过对多套数据的分析和比较,对我国出生性别比究竟有多高、目前我国人口出生性别比的数据是否可靠、出生性别比数据存在的问题以及导致这些问题的原因等一系列问题进行分析。研究发现,普查数据中0岁人口组性别比明显偏低,该年龄组的数据质量不可靠,判断我国出生性别比水平的态势应以其他低年龄组性别比的数据为主。普查数据中低年龄组又存在一定程度的女(婴)孩漏报的现象,导致低年龄组性别比一定程度的虚假性升高,影响了对我国真实出生性别比水平的判断。但是,即使扣除了这个因素,各个年龄组的性别比依旧远远高于正常值。所以,中国人口的出生性别比水平偏高的情况是真实的,只是真实的出生性别比水平并没有普查数据所显示的那么高。     

粤闽浙三省新移民身份特征的比较分析

根据侨情调查和人口普查资料,通过对粤、闽、浙三省新移民出国时身份特征的比较发现．就粤、闽、浙三省新移民的自然属性来说,粤籍新移民年龄层次的多元化特点明显,性别比例平衡：浙籍新移民的年龄较集中在青壮年,但也呈现多元化的趋向,性别比例不大平衡：而闽籍新移民青壮年比例最高,性别比例失衡。就粤、闽、浙三省新移民的社会属性来说,粤籍新移民文化程度最高,浙籍次之,闽籍最低;三省新移民的职业身份都以农民、工人为主,但广东、浙江新移民职业结构的多元化特征明显,而福建新移民的职业层次相对较低。造成粤、闽、浙三省新移民身份特征的差异主要是三省侨乡不同的社会经济背景和移民传统、新移民迁移的不同途径以及目标国的移民政策。     

Surplus Chinese Men: Demographic Determinants of the Sex Ratio at Marriageable Ages in China

We explore the demographic factors contributing to China's unbalanced sex ratio at marriagable ages. We develop a stable population model of the sex ratio at marriagable ages, and compare a series of population projections with alternative underlying assumptions about the key demographic inputs. The stable population model demonstrates that several demographic factors interact to influence the sex ratio at marriagable ages, including the sex ratio at birth, population growth, the age gap of marriage partners, and the sex ratio of survival from birth to marriageable age. The population projections further demonstrate that policies that seek to reduce the sex ratio at birth and the age gap at marriage and, to a lesser extent, increase fertility would be most effective at alleviating the problem. But no demographic changes are likely to occur quickly enough to balance the sex ratio at marriagable ages in the near future.     

90年代以来中国夫妇年龄差变动趋势及其原因分析

夫妇年龄差的研究是人口学研究的一个重要领域。但目前的研究由于数据来源多样化,得出的结论不尽一致,关于年龄差的变化方向也没有形成定论。为此,本文利用我国三期妇女地位调查数据,对年龄差变动趋势进行分析。结果发现：我国同龄婚配的特点非常稳定,其比例维持在16％～17％之间。中国夫妇年龄差模式自90年代以来,发生了较大的变化,2010年中国传统的＂男高女低＂的婚配模式有所改变,这种＂男高女低＂婚姻明显下降,而＂女高男低＂婚姻明显升高,扣除同龄婚后二者平分秋色。其原因可能与我国出生性别比持续偏高和婚姻观念的转变等因素有关。     

Does the marriage market sex ratio affect parental sex selection? Evidence from the Chinese census

Recent increases in the (male/female) sex ratio at birth in eastern Asia are thought to be associated with a preference for sons and to result from parental sex selection. However, males are less likely to marry and to have offspring as the ratio increases, and that decreases the expected number of grandchildren. Using data from the 2000 Chinese census, we test whether the sex ratio in the marriage market has an effect on the gender of subsequent births and hence on the sex ratio of the birth cohort. The slow population growth caused by the Great Famine in the early 1960s and the quick recovery that followed produced major changes in the sex ratio for those of marriageable age two decades later. We estimate that an increase of 1 % in the number of marriageable males relative to females, the marriage market sex ratio, would decrease the probability of having a son by 0.02 percentage points. That implies that the Great Famine, which occurred around 1960, led to an increase in the early 1980s of 5.8 extra male births per 100 females.     

A survey on the sex ratio at birth in Beijing]

A survey was conducted on the sex ratio at birth in Beijing for the period between 1964 and 1982. In the 1960s, birth control ideas and plans were first introduced. In the 1970s, birth control measures were gradually taken to curb the population growth. In the 1980s, the policy of 1 child for each married couple was adopted and put into practice. Although the birthrate is being maintained at a low level, the number of childbearing age women has increased, and the birthrate has shown some increase. Statistics show almost equality in the sex at birth, but the number of newborn boys is slightly higher than that of newborn girls. Under the influence of Chinese tradition, a great many people in the countryside still prefer to have boys rather than girls, and they might have reported fewer newborn girls than the actual number. The average sex ratio for the past 3 years has still been close to a balance. With the practice of 1 child for each family, the sex ratio has been maintained close to a balance. This overall situation is made possible because of the development in the quality of birth and eugenics and the improvement in health care.     

80年代以来我国少数民族出生人口性别比与生育水平变化的历史回顾

本文以“四普”、“五普”数据为基础,采用人口间接估计技术对20世纪80年代以来我国少数民族人口的生育水平和出生人口性别比变化的历史过程进行回顾,探讨生育水平下降过程中,出生人口性别比的变化趋势,并以蒙古族、回族和维吾尔族为例进行对比分析,结果表明当生育水平下降到较低水平时与出生人口性别比之间有明显的相关关系。     

出生人口性别比的变动趋势及其影响因素——一种国际视角的分析

在对半个多世纪以来国际学术界有关出生人口性别比及其影响因素研究成果总结和述评的基础上,利用收集到的典型发达国家的出生人口数据,对出生性别比的长期变动趋势、种族(民族)差异及母亲年龄与出生性别比的统计关系等进行了实证分析,旨在更全面、客观和准确地了解和认识出生人口性别比指标,为中国出生人口性别比研究提供借鉴和启示。     

Indirect evidence of the contribution of prenatal sex selection practices to the high sex ratio at birth in Vietnam

This paper reports indirect evidence that prenatal sex selection is a contributor to the recent increase in sex ratio at birth in Vietnam. The paper uses birth data from the Population Change Survey 2006 to assess the associations between sex ratio at birth and variables that predict increased opportunities to practise prenatal sex selection, including maternal knowledge of foetal sex before birth, the use of ultrasound for foetal sex determination, the gestation week when foetal sex was disclosed, and access to abortion services. The high sex ratio of most recent births was significantly associated with the use of ultrasound to determine the foetal sex in gestation weeks 12–22 and with access to family planning services that provide abortion. Prenatal sex selection in health facilities are likely to contribute to the recent increase in sex ratio at birth in Vietnam.     

The influence of mumber and ages of children on residential mobility

Married couples without children are more geographically mobile than those with children, at least through age 45. Among husband-wife couples with children, ages of children exercises a consistent mobility differential; when age of family head is controlled for, families with children under 6 years old only are the most mobile both within and between counties, followed by those with children under 6 and 6–17 years old, and followed in turn by families with children 6–17 years old only. The relationship between number of children and the probability of moving within counties has a reverse J-shape for family heads at each age under 45; after age 45 the relationship assumes a more normal J shape. Number of children is inversely related to the probability of migrating (moving between counties) for husband-wife families in which the husband is under 35; after age 35 the relationship is erratic. The effect of ages of children generally holds for each size of family. Female family heads with children are generally more geographically mobile than male family heads (wife present) at the same age and with the same number and ages of children present.     

中国出生性别比偏高及未来女性赤字预测

1980年代以来,中国人口出生性别比开始偏高且持续增高,2000年出生性别比已经达到116.9。出生性别比偏高不仅表现在分孩次的差异上,而且还表现出了明显的地区分布特征。本文利用“五普”数据资料为基期,对1980年后出生、并受出生性别比持续升高影响的人口进行预测,分析30年间的分城乡、分年龄的女性赤字规模及其变化趋势。     

女性地位低的层级推演--对出生性别比偏高背后隐象的探析

目前学术界对出生性别比偏高原因的争论主要集中在出生婴儿性别次序先后与下一孩次性别关系以及计划生育政策和女婴存在漏报、瞒报的影响等三个方面,本文在对三大传统观点提出质疑的基础上,先从生物学、计划生育政策、医学技术三个方面,而后从性别偏好,最后从女性地位低这三级递进的层次,推演和探析出生性别比偏高的原因,从而明晰出生性别比偏高的终极原因在于女性地位低这一事实。并努力从女性地位、男性偏好以及出生性别比三者关系上构造出一个新的分析框架。     

[Also talking about China's population sex ratio].]

The author points out that China's sex ratio is similar to the global sex ratio. Since 1960, the sex ratio in China has fluctuated around 105. The third national census in 1982 indicated a sex ratio for China of 106.3. The author analyzes the sex ratios at birth, in different age groups, and at death, as well as the main causes of death.     

Sex Ratio at Birth and Infant Mortality Rate in China: An Empirical Study

In this article, we used the data from the last three population censuses of China in 1982, 1990 and 2000, to study the dynamics of the sex ratio at birth and the infant mortality rate in China. In the late 1970s, China started its economic reform and implemented many family planning programs. Since then there has been great economic development and a dramatic decrease in fertility in most of its provinces. Along with these achievements, the sex ratio at birth of the Chinese population has increased to significantly more males to females, and in some provinces of China reached unprecedented levels. The ratio of infant mortality of the males to females for manyprovinces in China become extremely unbalanced with a much higher female infant mortality rate. In our study, we investigated the statistical relationship between the sex ratio at birth and the ratio of the infant mortality of males to female. Social and economic reasons for these unnatural trends are also discussed.     

Inheritance of sex ratio in the Kanzawa spider mite,Tetranychus kanzawai Kishida

Summary The frequency distributions in sex ratios of offspring from 4 fieldTetranychus kanzawai populations were examined. No significant difference was observed between average sex ratios of the 4 populations, although there was a great variability within each population, especially in the population fromPueraia lobata. Using the population fromP. lobata, inbred lines with high (H) and low (L) sex ratios were selected. Crossing experiments between H and L showed that sex ratio is determined by the genotype of mothers. It seemed that sex ratio is cointrolled by several genes, with no cytoplasmic factor involved.     

文化因素对性别偏好的决定作用

中国传统文化中强烈的男孩偏好是导致高出生性别比的根本原因,且急剧的社会经济变革和有效的计划生育政策所导致的低生育率也起到了加剧的作用。国家生育调控导致夫妇在生育孩子数量和性别选择上的冲突,本质上是制度与文化的冲突。传统生育文化的力量是顽强和巨大的,并带有一定程度的继承性和历史滞留性,只有以一种新型生育文化去替代重男轻女、传宗接代的传统生育文化,才能逐渐弱化人们的性别偏好。     

Evaluation of the results of China's 1982 population census and the problems raised by the IUSSP Florence Conference]

The author discusses the evaluation by IUSSP members of China's 1982 population census and outlines questions raised at the 1985 conference in Florence. While the quality of the census data was generally favorably assessed by those attending the workshop, the following points were made: The population size, obtained by summing all age groups, is inconsistent with the total population recorded in the census; fertility, mortality, and national growth rates for the Chinese population over the years are different in various official publications; and the sex ratio, 1.08:1 in 1981, may be caused by underreporting.     

Temporal and spatial trends in the sex ratio at birth in Greece, 1960–2006: exploring potential environmental factors

Numerous studies have shown that the sex ratio at birth, defined as the relative number of male and female births, may be dramatically lower for small cohorts with high chemical exposures. Meanwhile, reports from different countries have shown recent declines in male births for the general population, perhaps implicating environmental factors. The sex ratio at birth has, therefore, been suggested by some as a sentinel environmental health indicator. This paper examines variation observed in sex ratio at birth in Greece since 1960. The analysis incorporates a number of demographic parameters including the age and nationality of the mother, partnership status and birth order, as well as urbanisation level. The latter is considered an indirect indicator of potential environmental incidence. Our main finding is that the sex ratio in Greece has experienced a slight, albeit statistically significant, downward trend, especially since 1980. Further, this decline is not attributable to changing demographics. Geographical differentiations were found to be quite significant: the sex ratio is significantly higher in rural areas compared to urban centres or Greater Athens, and this difference is increasing over time. We offer a preliminary interpretation suggesting that these temporal and spatial trends may, at least partly, be attributed to chemicals’ exposure due to higher levels of indoor and outdoor air pollution and different consumption habits encountered in urban settings. We argue that such possibilities warrant further research with explicit measures of exposure.

The imbalance of sex ratio at birth,and its causes and countermeasures in China

This news brief focuses on the sex ratio at birth (SRB) in China, its causes, and remedial efforts. A SRB has been evident since the 1980s. The SRB increased from 108.48 male/100 female births to 116.30 male/100 female births during 1981-94. A normal SRB in China during 1940-94 would have been 107 male/100 female births. The SRB rose every year after 1985, with the exception of 1988. Male births increased, while female births decreased. SRB declined with age. The sex ratio in 1991, was 112.3 for children aged 0-4 years, 108.38 for children aged 5-9 years, and 106.56 for children aged 10-14 years. SRB values were higher in more populous provinces and lower in less populous provinces. SRB values were lower in northwestern China than in southeastern China. SRB values of minorities were lower than the Han ethnic group. A high SRB will increase the proportion single in later years. In 1990, 7.86 million people aged 30-40 years were single, of whom 94.32% were males. The SRB is caused by second, third, or higher birth orders. In 1993, sex ratios were 105.60 for first births, 130.22 for second births, and 126.12 for third births. The imbalance is attributed to a preference for sons as inheritors of blood ties and as family physical laborers. The imbalance is due to strict birth control and people's refusal to report female births. There is a need to increase awareness of the consequences, to increase old-age pensions and social security, to increase women's status, and to prohibit sex determination of a fetus. The family structure should emphasize its consumptive capacity rather than its function as a production unit.