Contraceptive practice required to meet a prescribed crude birth rate target: a proposed macro-model (tabrap) and hypothetical illustrations

TABRAP (TArget Birth Rate Acceptor Program) is a computer programmed model that provides a direct solution to the problem of determining the total annual numbers of contraceptive acceptors required to achieve a prescribed crude birth rate target path. Applied to an initial population for which age structure, the fertility schedule, and expected trends in life expectancy and age-specific proportions of females married are known, TABRAP incorporates the following factors: age at acceptance, with acceptors drawn from currently married nonusers; age-method-specific attrition rates of users; a potential fertility schedule of acceptors that allows for aging and sterility; and allowance both for postpartum anovulation and nine months for gestation to time properly the averted births. TABRAP generates annual data on acceptors, couple-years of use, births averted and age-specific fertility rates that meet the crude birth rate target. Resulting changes in population size, age structure and crude vital rates, also yielded, are invariant with respect to acceptor age and method mix. Assuming a target to reduce the crude birth rate from 45 to 30 in ten years, TABRAP is illustrated for seven mixes of acceptor age-method combinations applied to a population approximately that of Thailand, circa 1965.     

A new estimate of permanent sterility by age: sterility defined as the inability to conceive

The proportion of couples permanently sterile beyond a certain age is an important component of the reproductive process. Unless medical assistance is used, this age is the upper bound of the fecund period. Most estimates of sterility by age of the woman have been derived from natural fertility populations, in which the number of births and the timing of the last birth (of the complete reproductive history) were not controlled by the couples. Because data on these populations do not include pregnancies not ending in a live birth, the sterility estimates apply to the proportion of couples unable to conceive and to have a live birth. For this reason, it is useful to have an estimate of sterility based on the risk of conceiving, independently of the fate of the pregnancy. Using this new estimate, sterility increases with age much more slowly than with most previous estimates.     

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.     

Fertility in black Africa

The number of children per woman is between 6 and 7 children in Black Africa. Infertility and poor fertility existing in certain regions of Africa only appear in results concerning central Africa. 6-10% of births occur in women between the ages of 40 and 50. It must be noted that the goal of the majority of societies in Black Africa is to have numerous descendants. Factors of fertility in Africa examined are: precocious marriage, a long period of exposure to the risk of pregnancy, birth spacing and pathological infertility. The paper also discusses modern contraception and birth control, the improvement of sanitation conditions as part of the battle against infertility and infant mortality, combating infertility, decreasing infant mortality and governmental attitudes toward fertility control. Despite the efforts of several private and governmental agencies to promote family planning, progress in Africa has been modest. In the majority of Black African countries, women do not have access to contraception. In rural areas, the absence of an administrative infrastructure prevents diffusion of information and access to contraception. Improving general health conditions has 2 consequences on fertility: it reduces infertility due to diseases that cause sterility and it reduces infant mortality which affects birth intervals. So far birth control has only been successful among the very educated women. However, a great potential for more users exists.     

Assessing the effects of intermediate variables on birth interval-specific measures of fertility

This paper proposes a technique to simultaneously assess the effect of selected intermediate variables on the dynamics of birth intervals and to aggregate such effects across births of different order. The essentials, virtues and limitations of other approaches are 1st summarized. A method to link measures of birth interval dynamics to aggregated measures of fertility such as the age-specific fertility rates and total fertility is explained. A set of operations is suggested, required to translate estimates of birth interval-specific effects of intermediate variables into aggregate effects (e.g., effects at the level of fertility rates). These operations effectively permit the synthesis of results from multivariate procedures and those of techniques aimed at decomposing the effects of intermediate variables. Discussed are estimation and measurement procedures to deal with deal available from retrospective interviews carried out as part of the World Fertility Survey (WFS) program. The effects of marriage pattern are not considered. The effects of lactation are measured by using a dichotomous variable with a value of 1 if the preceding child was breast fed for at least as long as 9 months less than the beginning of the segment of interest and 0 otherwise. Following the assignment of a measure of effectiveness, 3 groups are distinguished in measuring contraceptive use: non-contraceptors, those using an ineffective method, and effective contraceptors. With respect to measuring the effects of induced abortion and spontaneous fetal losses, a variable is created indicating whether or not a birth leading to a fetal loss or the fetal loss itself had occurred within the segment being examined. 2 indicators, 1 a binary variable and the other aimed at measuring gradations of sterility are introduced to measure exposure to intercourse and sterility. Logit regression coefficients for selected intermediate variables are presented for Peru. The tables reveal the power of the variables measuring contraception. The evidence offers strong indications to support the contention that some form of birth control makes a difference as it does to confirm a priori expectations about success of different types of users. The inhibiting effects of breast feeding are generally in the direction expected but they are not always statistically significant. They appear to be stronger at higher parities and more intense in the earlier parts of the birth intervals. The effects of the variable representing continuity of marital union are surprisingly strong and significant for all segments of 10 months of width and for all births of order higher than 1.     

Fertility Following an Unintended First Birth

Research on unintended fertility tends to focus on births as isolated events. This article expands previous research by examining the relationship between early unintended childbearing and subsequent fertility dynamics in the United States. Data from the 2002 National Survey of Family Growth show that 27.5% of mothers report an unintended first birth. We use event history methods to show that these women are significantly more likely than women with an intended first birth to have an unintended second birth than to have either no second birth or an intended second birth, net of sociodemographic characteristics. An unintended first birth also increases the risk of having an unintended third birth relative to no birth or an intended birth, independent of the intendedness of the second birth. We conclude that early unintended fertility is a strong signal of high risk for subsequent unintended fertility.     

A cohort analysis of the timing of first birth and fertility in Ghana

This paper examines the nature of the inverse association between age at first birth and fertility across successive generations of Ghanaian women. Within the context of enhanced non-marital opportunities for contemporary women and declining fertility, we develop a rationale for and test the hypothesis that in a medium fertility environment as currently found in Ghana, the effect of age at first birth on fertility becomes more important than ever before. Five birth cohorts were identified (1938–1944; 1945–1949;1950–1954; 1955–1959; 1960–1964)from a merged file of the 1988, 1993 and 1998 Ghana Demographic and Health Surveys. The analyses were restricted to women over 35 years old at the time of the surveys, which allowed us to use current parity as a reasonable proxy for completed fertility. Preliminary results suggest that women who had first births early tend to have a higher number of births than those whose first births occur late, regardless of birth cohort. In multivariate analyses, the effect of age at first birth as a determinant of fertility was found to be more substantial among later cohorts. The implications of the findings are discussed.     

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.     

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.     

On Postponement and Birth Intervals

Much of the literature on fertility transition presumes that birth control is practiced either to limit family size or to space births. This article argues that women also use birth control to postpone pregnancy. Postponement is not synonymous with spacing. It arises when women delay their next birth for indefinite periods for reasons unrelated to the age of their youngest child, but without deciding not to have any more children. Postponement has a distinctive impact on the shape of birth‐interval distributions that differs from the impacts of family size limitation, birth spacing, or a mixture of the two behaviors. Some populations, such as that in South Africa, have developed fertility regimes characterized by birth intervals far longer than can be accounted for by birth spacing. Postponement of further childbearing that eventually becomes permanent may be an important driver of the transition to lower fertility in sub‐Saharan Africa.     

Comparing alternative statistics on recent fertility trends in Australia

In recent years fertility statistics in the Australian Bureau of Statistics (ABS) publication Births, Australia have suffered from a number of issues, including delayed receipt of registration data from the Registrars and computer processing errors. They prompt questions about the quality of these statistics for measuring the level of fertility and its year-to-year changes. The aim of this paper is to compare three sets of fertility statistics, (1) ABS birth registrations, (2) ABS births by year of occurrence, and (3) births in the Australian Institute of Health and Welfare National Perinatal Data Collection (NPDC), at the national and state/territory scales. Annual births by state/territory of usual residence from the three data sources were obtained for the period 2004–2013 or 2004–2014. Recast Estimated Resident Populations from the ABS were used to calculate Total Fertility Rates. For some states and territories there are non-trivial differences in fertility as recorded by the three data sources. In Queensland the trend in fertility according to ABS birth registrations is quite different from that based on the NPDC; in Tasmania and the Northern Territory birth registrations exceed NPDC births by a notable margin. There appears to be more uncertainty about the levels and annual changes in Australian fertility than many users of the data may realise. All three fertility datasets seem to possess some limitations. It is suggested that a new Australian fertility database be created which employs data linkage to incorporate both birth registrations and perinatal data.     

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.     

The Quality of Male Fertility Data in Major U.S. Surveys

Researchers continue to question fathers’ willingness to report their biological children in surveys and the ability of surveys to adequately represent fathers. To address these concerns, this study evaluates the quality of men’s fertility data in the 1979 and 1997 cohorts of the National Longitudinal Survey of Youth (NLSY79 and NLSY97) and in the 2002 National Survey of Family Growth (NSFG). Comparing fertility rates in each survey with population rates based on data from Vital Statistics and the U.S. Census Bureau, we document how the incomplete reporting of births in different surveys varies according to men’s characteristics, including their age, race, marital status, and birth cohort. In addition, we use Monte Carlo simulations based on the NSFG data to demonstrate how birth underreporting biases associations between early parenthood and its antecedents. We find that in the NSFG, roughly four out of five early births were reported; but in the NLSY79 and NLSY97, almost nine-tenths of early births were reported. In all three surveys, incomplete reporting was especially pronounced for nonmarital births. Our results suggest that the quality of male fertility data is strongly linked to survey design and that it has implications for models of early male fertility.     

Did Australia’s Baby Bonus Increase Fertility Intentions and Births?

In May 2004, the Australian government announced a “Baby Bonus” policy, paying women an initial A$3,000 per new child. We use household panel data from the Household, Income and Labour Dynamics in Australia Survey (N = 14,932) and a simultaneous equations approach to analyze the effects of this bonus on fertility intentions and ultimately births. The results indicate that opportunity costs influence intentions and births in predictable ways. Fertility intentions rose after the announcement of the Baby Bonus, and the birth rate is estimated to have risen modestly as a result. The marginal cost to the government for an additional birth is estimated to be at least A$3,000 per new child. We use household panel data from the Household, Income and Labour Dynamics in Australia Survey (N = 14,932) and a simultaneous equations approach to analyze the effects of this bonus on fertility intentions and ultimately births. The results indicate that opportunity costs influence intentions and births in predictable ways. Fertility intentions rose after the announcement of the Baby Bonus, and the birth rate is estimated to have risen modestly as a result. The marginal cost to the government for an additional birth is estimated to be at least A126,000.     

A study on the effectiveness of sterilizations in reducing the birth rate

This study analyzed 1,081 women in Kerala State (India) who were either sterilized or were the wives of sterilized men, and by examining the fertility among a comparable group of 1,000 other women, estimated the number of prevented future births per 1,000 women in the sterilized group. The results of this estimation were then applied to project what the entire savings in births might be over a 3D-year period in the entire Kerala population if each year there were one, three, or five sterilizations performed per 1,000 of total population. The results failed to confirm the hope that the crude birth rate would be decreased by 12 per 1,000 in a decade merely by sterilization of five per 1,000 of the population per annum. The study also discusses various measures of reduction in the crude birth rate. By a reasonable measure, the reduction in the crude birth rate for Kerala from such a sterilization program is estimated as seven points after a decade or nine points after three decades, reflecting decreases of 21 and 36 per cent, respectively, in the number of births.     

Fertility and desired fertility: Longitudinal evidence from Thailand

Summary The validity and usefulness of 'desired additional children' and 'ideal family size' as predictors of fertility are analysed in this paper on the basis of longitudinal survey data from Thailand. First, the extent of measurement error in these variables is considered, and it is concluded that the error variance and the true variance are of similar orders of magnitude. Secondly, the changes in attitudes subsequent to births and deaths of children are investigated. It is found that the number of additional children desired is decreased by births and increased by deaths, but less than would be expected if 'desired additional children' represented an unchanging target family size. 'Ideal family size' is almost unaffected by births and deaths. Thirdly, the contribution of attitudinal variables to behavioural models is examined. It is found that desired fertility is explained no better than fertility in a standard economic model. A birth function separating desired children from identifiable physiological factors as explanatory variables indicated that the former was just significant. A model of contraceptive acceptance also found desired fertility to be a significant determinant. Thus, desired fertility can be successfully integrated into behavioural models. But on the whole, its explanatory power was weak, and it was concluded that the independent use of this variable does not significantly improve on models which relate fertility to socio-economic variables directly.     

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.     

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。     

The third birth in Sweden

This paper considers the formulation, estimation and interpretation of microdynamic models of fertility. Our model explains parity choices, sterility, childlessness, interbirth intervals and initiation of pregnancy within a unified framework. We develop a general methodology for estimating the determinants of transition times to births of different orders. Our procedure incorporates time-varying explanatory variables and unobservables. We present conditions that justify conventional formulae relating hazards to survivor functions when time-varying variables enter hazards. We also consider the validity of widely-used piecemeal estimation strategies that focus on one birth at a time. We consider methods for selecting a best model among a class of non-nested models. Two criteria are set forth and used to evaluate the detminants of third births in Sweden.We find that two models fit Swedish microdata equally well. One model is consistent with neoclassical economic theory. It assigns a central role to the wages of men and women in explaining the timing and spacing of births. The other model is purely demographic and excludes wages. Purely statistical criteria cannot distinguish these models although in other work we show that the economic models are more parsimonious in terms of the number of parameters that must be estimated and are better able to forecast aggregate time series.We demonstrate how to interpret the output of multistate fertility models. Wage effects on third births are decomposed into two components: (a) an in direct effect that determines whether a woman is at risk to have a third birth, and (b) a direct effect on the transition rate to the third birth given that a woman has had two births. We find that female wages play an important role in postponing first births but play only a minor role in explaining childlessness. Female wages substantially affect third births. Male wage effects are weaker. We find that female wage effects weaken for more recent cohorts of women. This evidence is consistent with the introduction of progressively more pronatal Swedish policies.This research was supported by NIH Grant No. HD-19226 to NORC. We have benefited from the comments of Elja Arjas and Ricardo Barros. This paper was presented at an IUSSP Conference in Paris, France, in March 1988, and as an invited lecture at the Fourth ESPE Meetings in Istanbul, Turkey, June, 1990. This paper is one part of a trilogy. Heckman and Walker (1990a) presents a succinct summary of the main economic results. Heckman and Walker (1990b) presents a more complete discussion of the empirical results. This paper presents a more purely demographic discussion.     

Some aspects of the use of birth expectations data from sample surveys for population projections

The value of national sample survey data relating to birth expectations for projecting births is reassessed in the light of data limitations pointed out by Ryder and Westoff among others and of the methods of projection used by the United States Bureau of the Census. The annual level of fertility under the cohort-fertility projection method depends on the assumptions regarding completed fertility, about which the available survey data are fairly informative, and on the assumptions regarding the timing of births, about which the survey data tell us very little. Test calculations suggest that Ryder and Westoff have overstated the significance of timing relative to completed family size for the level of future births. We believe that the fall in the annual total fertility rate in the first half of the sixties is to be explained only in part by a general delay in childbearing; a moderate to substantial decrease in completed family size has also occurred. Analysis of the latest set of fertility projections of the Census Bureau also suggests that the assumptions about completed fertility are a much more important determinant of the level of future births than timing, both in the short and long term. Although the available expectations data cannot help in predicting short-term annual changes in fertility, they appear useful for making long-term projections of annual fertility. Expansion of the size, frequency, and content of the sample surveys and incorporation of parity and birth interval into the projection method may improve projections.