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Biomedical subjects

J Bongaarts

Publications and source records attributed to J Bongaarts.

35 records · Page 2Linked to original sources
PubMed1979

Effect of maternal nutritional status and infant supplementation during lactation on postpartum amenorrhea.

This paper explores the effects of maternal nutritional status and food supplementation ingested by the infant on the duration of postpartum amenorrhea. A significant negative association was found between the nutritional status of the mother during the third trimester of pregnancy and the length of postpartum amenorrhea. A negative association was also found between infant supplementation and duration of postpartum amenorrhea. Each of these associations remained significant after controlling for the other, suggesting that both factors independently affect the length of postpartum amenorrhea.

Amenorrhea↗
PubMed1975

Fertility rates and abortion rates: simulations of family limitation.

A computerized model that simulates reproductive events during the childbearing years of a cohort of women is used to analyze the impact of contraception and induced abortion on fertility. Four different reproductive regimens are investigated: (2) contraception only, (2) abortion only, (3) abortion as a backstop to contraception, and (4) combinations of abortion and contraception. It is concluded that in historical as well as in modern populations, levels of fertility near replacement are unlikely to be obtained without the use of induced abortion.

Abortion, Induced↗
PubMed1975

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.

Adolescent↗
PubMed1975

A method for the estimation of fecundability.

A new method for the estimation of the mean and variance of fecundability is described. The data input required for this procedure is the distribution of the interval from marriage to first birth, or from the resumption of the conception risk after contraction to the subsequent birth. The estimates of the mean and variance of fecundability are obtained by fitting a model to the observed interval distribution. To test the method, it is applied to data from five historical populations. The fecundability means in these populations ranged from 0.18 to 0.31 while the co-efficients of variation all had values near 0.56. A short method for the estimation of the mean of fecundability based on the same model, but not requiring a computer, is also presented.

Abortion, Spontaneous↗
PubMedDate not supplied

The formal demography of families and households: an overview.

"The objective of the present paper is to give a brief overview of the subject matter of the formal demography of the family. Selected references are included, but no attempt is made to be exhaustive. No discussion of socio-economic determinants or consequences is included, because this overview is limited to the formal aspects of the field. "The...paper is divided into five parts. The first deals with the descriptive analysis of family and household size and composition, from both a cross-sectional and a longitudinal perspective. The next two sections discuss, in order, demographic determinants and consequences. This is followed by a brief section on projection methods and the conclusion."

Demography↗
PubMedDate not supplied

The demographic impact of family planning programs.

In response to concerns about the adverse consequences of rapid population growth, family planning programs have been implemented in many developing countries. The aim of the present study is to assess the impact of this programmatic approach on long-range population growth. The result of a new and hypothetical population projection indicates that in the absence of family planning programs the population of the developing world could be expected to reach 14.6 billion in the year 2100 instead of the 10 billion that is currently projected by the World Bank. Despite the apparent success of existing interventions, fertility control is far from complete, as many women continue to bear unwanted births. To assess the impact of this unintended childbearing a second hypothetical projection is made. With perfect implementation of reproductive preferences, the population size of the developing world in 2100 would be reduced by an estimated 2.2 billion below the current projection. Further strengthening of family planning programs and improvements in birth control technology are therefore likely to provide important demographic benefits.

Contraception Behavior↗
PubMedDate not supplied

Contraceptive use and annual acceptors required for fertility transition: results of a projection model.

Major fertility declines in developing countries are invariably accompanied by large increases in contraceptive prevalence and in the annual number of new acceptors. This article applies a target-setting model to make hypothetical projections of trends in prevalence and number of acceptors over the course of a full fertility transition. The sensitivity of these trends to variations in proximate determinants such as the marriage pattern and the duration of lactational amenorrhea, as well as in the discontinuation rate and the method mix, are examined. It is concluded that a contraceptive prevalence of around 75 percent is needed to achieve replacement-level fertility and that variations in proximate determinants other than contraceptive prevalence have only a modest effect on this result. On the other hand, trends in new acceptors are demonstrated to be very sensitive to discontinuation rate changes. As a consequence, it is generally difficult to draw conclusions about trends in fertility from trends in acceptors.

Adolescent↗
PubMedDate not supplied

A simple method for estimating the contraceptive prevalence required to reach a fertility target.

This report describes and applies a procedure for estimating the increase in contraceptive prevalence that would have to occur to achieve specified future reductions in a population's fertility. This target-setting methodology is based on a previously developed analytic model for the relationship between fertility and its proximate determinants. The basic aggregate version of the estimation procedure, which is described in detail, requires relatively few input data, but it allows changes in the mix of contraceptive methods in future years. In extended versions of the model, age specificity and adjustments for given trends in the proximate determinants other than contraceptive use are introduced.

Contraception Behavior↗
PubMedDate not supplied

Building a family: unplanned events.

Couples in developed societies are often unsuccessful in achieving precise family building goals despite the widespread use of birth control. Unplanned events that frustrate reproductive intentions to varying degrees include contraceptive failure, sterility, miscarriage, prolonged conception delay, undesired sex combination of offspring, divorce, and the death of a spouse or a child. This paper reviews the probability of the occurrence of these events using US data. It is concluded that the large majority of newlyweds will experience at least one unplanned event during the family building phase of the life cycle.

Congenital Abnormalities↗
PubMedDate not supplied

The fertility-inhibiting effects of the intermediate fertility variables.

Based on the application of an aggregate reproductive model, this study demonstrates that a small number of intermediate fertility variables are responsible for most of the variation in fertility levels of populations. Four variables--proportion married, contraception, induced abortion, and postpartum infecundability--are generally the most important determinants of fertility; the other intermediate factors are of less interest except in unusual circumstances. These four factors explain 96 percent of the variance in the total fertility rate in a sample of 41 populations that include developing and developed countries as well as historical populations. In the last section, the average fertility effect of the principal intermediate fertility variables is estimated for groups of contemporary populations with different total fertility rates.

Abortion, Induced↗
PubMedDate not supplied

The causes of unmet need for contraception and the social content of services.

Since the 1960s, survey data have indicated that substantial proportions of women who have wanted to stop or delay childbearing have not practiced contraception. This discrepancy is referred to as the "unmet need" for contraception. The traditional interpretation, that these women lack access to contraceptive supplies and services, has led in turn to an emphasis on expanding family planning programs. This study analyzes survey data and related anthropological studies on the causes of unmet need and concludes that the conventional explanation is inadequate. Although for many environments geographic access to services remains a problem, the principal reasons for nonuse are lack of knowledge, fear of side effects, and social and familial disapproval. This finding underscores the need for expanded investment in services that not only provide contraceptives, but also attend to closely related health and social needs of prospective clients. Programs are likely to be most successful when they reach beyond the conventional boundaries of service provision to influence and alter the cultural and familial factors that limit voluntary contraceptive use.

Contraception Behavior↗