The construction of the fertility model of variable parity from family planning practice]

Understanding the changing patterns of age specific fertility under the planning system is essential for building a fertility model which reflects birth control policy implementation in China. In building a Parity Variable Fertility Model, 4 basic elements are to be considered: 1) psychosocial, and physiological variables, 2) patterns of the total fertility rate and age-specific fertility rate, 3) socioeconomic development, and 4) distribution of parity-specific fertility. THe natural fertility of women is 17, calculated from a 309-years childbearing period, with 17% of non-susceptible time. In China, about 86% of natural fertility is suppressed by various factors. In this model, the following variables are included: 1) The first marriage ratio, which is the proportion of women in each age group which enters into a first marriage. The range and spread of this ratio is closely associated with the first birth. 2) The first birth ratio, which is the proportion of a marriage cohort to have a first birth each year. 3) the birth interval, which determines the distribution of second births. 4) Regulation coefficient B, which represents birth control regulations which approximately determine the number of second-parity or higher order births. The difference between the fertility level generated from the Parity Variable Fertility Model and reality depends on the implementation of birth control program, the assumptions on regulation coefficients, and changes in social and cultural factors. The model is easy to use, especially for areas where the marriage and fertility records of women of child-bearing are well kept.     

中国的生育率:到底下降了多少?

1990年代以来 ,中国的生育水平持续下降 ,已经进入低生育国家的行列。 2 0 0 0年人口普查 ,中国的总和生育率为 1 2 2 ,明显存在漏报。那么中国的生育率到底下降了多少 ?本文利用亲生子女法、生育史重构法和胎次递进比方法分析了 1 990年代生育率的下降过程 ,认为 2 0 0 0年总和生育率最准确的估计应为 1 5 8。通过分解总和生育率的变化 ,认为 1 990年代生育水平的下降 ,2 /5归因于结婚年龄的推迟 ,3/5归因于婚内生育率的下降     

An evaluation of the recent fertility changes in Afghanistan: a parity-specific analysis

Very limited studies exist on the demography of Afghanistan. Using the only national survey with complete birth history data, the 2010 Afghanistan Mortality Survey, this paper describes the recent fertility changes in the country from a parity-specific perspective. From 1995 to 2009, parity progression ratios, average birth intervals, sex ratio at birth by parity and synthetic lifetime average parity are successively examined. Results show that the progression to higher-order births started to decline in the early 2000s and was accompanied by childbearing postponement. The consistency of the parity analysis is assessed by looking at the sex ratio at birth by parity and comparing the synthetic lifetime average parity to fertility estimates computed from other datasets and/or estimation methods. While the sex ratio at birth indicates strong distortion, casting doubt on the ultimate fertility level, the consistency of the parity-based fertility estimates with other fertility estimates corroborates the fact that misreporting the sex of the child is mainly causing the imbalanced sex ratio at birth and is not significantly affecting the level of fertility. The SPPRs-based analysis provides solid evidence that Afghanistan is in the early stage of its fertility transition.     

Age at last birth and its components

This paper examines the ways in which the behavior of twentieth century cohorts of American women changed simultaneously in the three components of fertility that determine age at last birth--age at first birth, spacing between subsequent births, and parity progression ratios of subsequent births--to produce changes in the timing of the completion of childbearing. It decomposes changes in the mean age at last birth among cohorts and between whites and nonwhites to changes in these three components. To perform these analyses, we developed and applied a method to estimate the distributions and means of ages and last births, birth intervals, and parity progression ratios from age- and parity-specific fertility rates available from vital statistics data. Results show that the cohorts increased and decreased their age at first birth, birth intervals, and parity progression ratios of lower and higher birth orders in almost every possible combination so as to achieve a relatively young age at final birth.     

Using Discrete-Time Event History Fertility Models to Simulate Total Fertility Rates and Other Fertility Measures

Event history models, also known as hazard models, are commonly used in analyses of fertility. One drawback of event history models is that the conditional probabilities (hazards) estimated by event history models do not readily translate into summary measures, particularly for models of repeatable events, like childbirth. In this paper, we describe how to translate the results of discrete-time event history models of all births into well-known summary fertility measures: simulated age- and parity-specific fertility rates, parity progression ratios, and the total fertility rate. The method incorporates all birth intervals, but permits the hazard functions to vary across parities. It can also simulate values for groups defined by both fixed and time-varying covariates, such as marital or employment life histories. We demonstrate the method using an example from the National Survey of Family Growth and provide an accompanying data file and Stata program.     

Multivariate analysis of parity progression—based measures of the total fertility rate and its components

This article describes a methodology for applying a discrete-time survival model—the complementary log-log model—to estimate effects of socioeconomic variables on (1) the total fertility rate and its components and (2) trends in the total fertility rate and its components. For the methodology to be applicable, the total fertility rate (TFR) must be calculated from parity progression ratios (PPRs). The components of the TFR are PPRs, the total marital fertility rate (TMFR), and the TFR itself as measures of the quantum of fertility, and mean and median ages at first marriage and mean and median closed birth intervals by birth order as measures of the tempo or timing of fertility. The focus is on effects of predictor variables on these measures rather than on coefficients, which are often difficult to interpret in the complex models that are considered. The methodology is applicable to both period and cohort data. It is illustrated by application to data from the 1993, 1998, and 2003 Demographic and Health Surveys (DHS) in the Philippines.     

Estimating the effect of child mortality on the number of births

This article rigorously derives the properties of the regression of births on child deaths. It is shown how the raw regression coefficient may be corrected for the effects of fertility on mortality so that the rate at which dead children are replaced may be estimated. The method is applied to data from Colombia. It is found that the mortality rate differs across individuals and is correlated with fertility. Such conditions vitiate the use of birth intervals and parity progression ratios yet can be dealt with using the new method. On average each death produces 0.2 new births as a direct result of the death. Fertility hoarding may raise the total fertility response to roughly one-half birth per death.     

Presentation and establishment of a system of total progressive fertility rates and relevant models

Demographic studies necessarily rely on adequate and accurate statistical data. To take into consideration China's present situation of population control and planned birth practice, a system of total progressive fertility rate (TPFR) different from the parity progression ratio is established and its relevant model presented in order to make indicators used in analysing women's 1st marriage and fertility level reflect as closely as possible the actual situation. Here, TFR and TPFR, both used in analyzing fertility level, are compared so as to show that TPFR is a methodology more appropriate for use in the analysis of China's fertility. The model is based on the fact that women's vital events happen progressively from being born to completing childbearing. In composing the model, both women's age structure and parity structure are considered and the regularity of their changes with different years is defined. In China, the population development program has been brought into the overall social and economic development plan. Thus it is necessary to practice planned birth in order to make the population develop in a way which is in keeping with the social and economic development. Compared with other models or theories, it is more realistic to use the model discussed above in studies on China's population policy.     

How Far Has Fertility in China Really Declined?

According to births in the last year as reported in China's 2000 census, the total fertility rate (TFR) in the year 2000 in China was 1.22 children per woman. This estimate is widely considered to be too low, primarily because some women who had out‐of‐quota births according to China's one‐child family policy did not report those births to the census enumerator. Analysis of fertility trends derived by applying the own‐children method of fertility estimation to China's 1990 and 2000 censuses indicates that the true level of the TFR in 2000 was probably between 1.5 and 1.6 children per woman. A decomposition analysis of change in the TFR between 1990 and 2000, based on our best estimate of 1.59 for the TFR in 2000, indicates that about two‐fifths of the decline in the conventional TFR between 1990 and 2000 is accounted for by later marriage and less marriage, and three‐fifths by declining fertility within marriage. The analysis also applies the birth history reconstruction method of fertility estimation to the two censuses, yielding an alternative set of fertility estimates that are compared with the set derived by the own‐children method. The analysis also includes estimates of trends in fertility by urban/rural residence, education, ethnicity, and migration status. Over time, fertility has declined sharply within all categories of these characteristics, indicating that the one‐child policy has had large across‐the‐board effects.     

Multidimensional Life Table Estimation of the Total Fertility Rate and Its Components

Using discrete-time survival models of parity progression and illustrative data from the Philippines, this article develops a multivariate multidimensional life table of nuptiality and fertility, the dimensions of which are age, parity, and duration in parity. The measures calculated from this life table include total fertility rate (TRF), total marital fertility rate (TMFR), parity progression ratios (PPR), age-specific fertility rates, mean and median ages at first marriage, mean and median closed birth intervals, and mean and median ages at childbearing by child’s birth order and for all birth orders combined. These measures are referred to collectively as “TFR and its components.” Because the multidimensional life table is multivariate, all measures derived from it are also multivariate in the sense that they can be tabulated by categories or selected values of one socioeconomic variable while controlling for other socioeconomic variables. The methodology is applied to birth history data, in the form of actual birth histories from a fertility survey or reconstructed birth histories derived from a census or household survey. The methodology yields period estimates as well as cohort estimates of the aforementioned measures.     

Low fertility due to delay in -- not dearth of -- births

Population Council demographer John Bongaarts and his colleague Griffith Feeney argue that recent concern about a lack of births overlooks the fact that many women in developed countries are simply choosing to bear children later than women used to. So-called birth dearths are often caused by temporary delays in childbearing. The two demographers have designed a new way for demographers to account for the timing, or tempo, of childbearing in estimates of fertility. Their tempo-adjusted total fertility rate (TFR) allows demographers to correct skewed fertility trends, such as those leading to projections of birth dearths. The new measure provides a better indication of women's true propensity to bear children. Standard measures of fertility are distorted by changes in tempo. Such changes occur when large numbers of couples delay or accelerate their initiation of family building. The authors used historical data and theoretical arguments to validate the tempo-adjusted TFR, which improves upon the two common measures of fertility. Flaws in the TFR and the completed fertility rate (CFR) are corrected by Bongaarts and Feeney's new measure. To demonstrate their new tool, they examined the below-replacement fertility seen in recent decades in the US. By the mid-1990s, the TFR in almost every developed country had fallen below the replacement level of 2.1 births/woman, and in Italy, Spain, and Germany it fell below 1.5. If such fertility persists, declining population size, extreme population aging, and financial pressure upon social security systems may result. However, if fertility preferences hold at current levels, the very low fertility rates observed in the developed world will approach 2 children/couple.     

Combining registration-system and survey data to estimate birth probabilities

With the widespread availability of event-history data, demographers have increasingly eschewed registration-system data in favor of survey data. We propose instead using survey and registration-system data in combination, via a constrained maximum-likelihood framework for demographic hazard modeling. As an application, we combine panel survey data and birth registration data to estimate annual birth probabilities by parity. The general fertility rate obtained from registration-system data constrains the weighted sum of parity-specific birth probabilities. The variances about the parity-specific birth probabilities are halved when registration-system data are used to constrain the estimates. Other demographic applications are discussed.     

Birth spacing and fertility limitation: a behavioral analysis of a nineteenth century frontier population

Our analysis of changing birth interval distributions over the course of a fertility transition from natural to controlled fertility has examined three closely related propositions. First, within both natural fertility populations (identified at the aggregate level) and cohorts following the onset of fertility limitation, we hypothesized that substantial groups of women with long birth intervals across the individually specified childbearing careers could be identified. That is, even during periods when fertility behavior at the aggregate level is consistent with a natural fertility regime, birth intervals at all parities are inversely related to completed family size. Our tabular analysis enables us to conclude that birth spacing patterns are parity dependent; there is stability in CEB-parity specific mean and birth interval variance over the entire transition. Our evidence does not suggest that the early group of women limiting and spacing births was marked by infecundity. Secondly, the transition appears to be associated with an increasingly larger proportion of women shifting to the same spacing schedules associated with smaller families in earlier cohorts. Thirdly, variations in birth spacing by age of marriage indicate that changes in birth intervals over time are at least indirectly associated with age of marriage, indicating an additional compositional effect. The evidence we have presented on spacing behavior does not negate the argument that parity-dependent stopping behavior was a powerful factor in the fertility transition. Our data also provide evidence of attempts to truncate childbearing. Specifically, the smaller the completed family size, the longer the ultimate birth interval; and ultimate birth intervals increase across cohorts controlling CEB and parity. But spacing appears to represent an additional strategy of fertility limitation. Thus, it may be necessary to distinguish spacing and stopping behavior if one wishes to clarify behavioral patterns within a population (Edlefsen, 1981; Friedlander et al., 1980; Rodriguez and Hobcraft, 1980). Because fertility transition theories imply increased attempts to limit family sizes, it is important to examine differential behavior within subgroups achieving different family sizes. It is this level of analysis which we have attempted to achieve in utilizing parity-specific birth intervals controlled by children ever born.(ABSTRACT TRUNCATED AT 400 WORDS)     

A model of the age patterns of births by parity in natural fertility populations

This research develops a convolution model to express the age patterns of fertility at each birth order in natural fertility populations in terms of six parameters, directly representing the proximate determinants of fertility, and a series of parity level indicators. The parity level indicators at each birth order are simply the proportions of women in a cohort who will eventually have births at each birth order it the age‐related fecundity decline is controlled. The Coale‐McNeil nuptiality model is adopted to represent the age pattern of first marriage rates and the natural fertility schedule employed in the Coale‐Trussell fertility model is incorporated to adjust age effects. The fast Fourier transform is used in solving the model numerically. It proves that the model is able to provide excellent fits to fertility for rural Chinese women in the 1950s.     

Lifetime probability of additional births by age and parity for American women, 1935–1968: A new measurement of period fertility

A new fertility measurement, probability that a woman of specified parity and age will bear a given number of births in her remaining lifetime, is proposed in this article. The measurement is a summary index of a set of age-parity-specific birth probabilities and in a particular case it is conceptually analogous to the total fertility by birth order but free from the influence of the parity distribution. Fertility of American women for the period 1935-1968 was studied by use of such lifetime probabilities. It appears that the trend of fertility of high birth orders has been parallel with that of low orders. Initiation of the recent decline in fertility depends on parity and age of woman.     

Changes in the Quantum of Russian Fertility During the 1980s and Early 1990s

To investigate whether Russia's dramatic fertility changes pre‐ and post‐Soviet times were due primarily to tempo effects, as has been argued recently, or to quantum effects, this study standardizes for factors that distort conventional fertility indexes. A time series spanning 1978–93 of period parity‐progression ratios for the Russian Federation is constructed applying the PADTFR technique, which takes into account age, parity, and time elapsed since the birth of the previous child, to data from the Russian micro census of February 1994 (2.8 million maternity histories). Both the fertility rise of the 1980s and the fertility fall of the early 1990s are found to be primarily due to changes in the probability of a second birth. The impact of tempo on the conventional TFR is significant, but of relatively minor magnitude in comparison to changes in the quantum of fertility. The social and economic context in which the fertility change took place is described.     

用孩次递进比模拟“全面二孩”政策调整初期的生育行为--以湖北省为例

以2014年湖北省卫生和计划生育委员会提供的包括“单独”、“双独”方面的数据为基础,描述了生育政策调整下被压抑的生育潜能释放的规律性和用孩次递进比的方法预测“全面二孩”政策调整初期的生育行为,与意愿分析方法相互比照,丰富了当下生育政策下生育行为预测研究。从分析结果可以看出,假定2016年“全面二孩”生育政策调整,湖北省第一年内会新增二孩出生量52621人,占湖北省2014年总出生量的7?41％;三年内最低会新增139262人的二孩生育量。城乡对比发现,农村新增二孩生育占到将近六成,且由抢生而导致的堆积主要集中在农村,40岁后的高龄抢生情况不严重。     

我国是否存在生肖偏好——基于总和生育率的实证分析

是否存在生肖偏好的问题是生育研究中的一个重要方面,现有的这方面的实证研究还存在不足之处。分析发现,总和生育率是用于判断是否存在生肖偏好的最佳指标,具体的实证分析方法有两种:一是基于总和生育率的生育堆积指数,逐年分析是否存在生肖偏好导致的生育堆积或回避现象;二是按生肖的惠普尔指数,从长周期来分析各生肖的生育堆积状况。分析1950-2017年我国总和生育率数据发现,从总体上来看,我国人口基本上不存在明显的因生肖偏好而发生的生育堆积或回避现象。     

Low Fertility Trap:Theories,Facts and Implications

The low Fertility Trap Hypothesis proposes that there are three self-reinforcing mechanism--demographic,sociological and economic,working towards a downward spiral in future fertility.Once TFR drops below 1.5,it will be difficult to recover.The fertility recovery emerging in many countries across the world has changed the lowfertility trap theory and also the justification of the theory itself.So low-fertility trap is more likely a pattern summarized from a short-time phenomenon than a generalized social law.As with China,the current fertility level is above 1.5 births per woman,and China is not in the "Low-fertility trap".Moreover,most recent surveys suggests that current fertility intention in China is above 1.8 births per woman and more than60 percent of people would have a second child if there is an adjustment of fertility policy.In addition,birth postponement is still playing an important role in reducing TFR in China.Thus,with the high fertility intention,adjustment of family planning policy and decreasing tempo effect,TFR in China will experience upturn but not further decline in the near future.It is lack of evidence to conclude that China has already been or is going to be trapped in low fertility.     

Regression analysis of the relationship between the birth rate and proportion of first order births in 1981]

Generally speaking, various fertility indicators such as the birth rate, average fertility rate, and total fertility rate have a close relationship. Various regression analyses have also been made by using different data on population statistics to describe their internal relationships. A regression analysis of the relationship between the birth rate and proportion of first order births, however, has not been made. Data collected by family planning staff at various places show that the places with a high rate of first order births normally have a lower birth rate, and the places with a low rate of first order births very often have a high birth rate. From here we may find that the proportion of the first order births is moving in two opposite directions, and there is no determined relationship between them. It is impossible to use one indicator to calculate the other's indicator. Only a regression analysis can be made to study the relationship between the two. The birth rate and proportion of first order births in 1981 showed some negative relationship, but the use of a regression equation should still be restricted. The regression equation between the birth rate and proportion of first order births may reflect a correct relationship when the region and the number of first order births are fixed. Therefore, any factor which has an impact on the number of first order births also has an influence on the use of regression equation.