Showing papers on "Fertility published in 1980"
TL;DR: Flow cytometry of heated sperm nuclei revealed a significant decrease in resistance to in situ denaturation of spermatozoal DNA in samples from bulls, mice, and humans of low or questionable fertility when compared with others of high fertility.
Abstract: Flow cytometry of heated sperm nuclei revealed a significant decrease in resistance to in situ denaturation of spermatozoal DNA in samples from bulls, mice, and humans of low or questionable fertility when compared with others of high fertility. Since thermal denaturation of DNA in situ depends on chromatin structure, it is assumed that changes in sperm chromatin conformation may be related to the diminished fertility. Flow cytometry of heated sperm nuclei may provide a new and independent determinant of male fertility.
800 citations
TL;DR: In this paper, it is argued that the primary determinant of the timing of the onset of the fertility transition is the effect of mass education on the family economy, at least partly because the relationships between members of the family are transformed as the morality governing those relationships changes.
Abstract: This article proposes mechanisms through which mass education produces declines in fertility and reviews the evidence both in the 19th century demographic transition in the west and in contemporary developing countries for such a relationship. It is argued that the primary determinant of the timing of the onset of the fertility transition is the effect of mass education on the family economy. The direction of the wealth flow between generations changes with the introduction of mass education at least partly because the relationships between members of the family are transformed as the morality governing those relationships changes. (Authors)
526 citations
TL;DR: This paper shows how the intensity of this selection is affected by male sexual behaviour, female choice, sex ratio, and modes of sperm precedence, and shows that the absolute intensity of sexual selection is unaffected by the system of sperm precedent.
437 citations
TL;DR: There are no longer any easy answers to infertility and when male infertility is the problem couples are turning in record numbers to donor insemination and other alternatives force the couple to face adjustments and issues that may be as difficult as the original problem of infertility.
356 citations
TL;DR: Although the total number of cases involved is small, a number of general principles emerge and individuals of either sex show a degree of variation in their response to irradiation.
Abstract: Increasing numbers of young people are now being cured of certain neoplasms by radiotherapy and chemotherapy. Such people will naturally wish to lead a normal life and possibly to have children. Therefore the question of the effect of radiation and cytotoxic drugs on the reproductive capacity of these patients has become important. The purpose of this report is to review the information available on the effect of radiation on fertility in man. Direct information on radiation effects on human fertility is available from reports on therapeutic exposure and deliberate experimental exposure. Although the total number of cases involved is small, a number of general principles emerge. In males, fractionated irradiation of the testes may be more harmful than acute, at least up to total doses of about 600 cGy (rad). Fractionated doses greater than 35 cGy cause aspermia, the time taken for recovery increasing with dose, and after more than 200 cGy aspermia may be permanent. In females, response varies with age as well as dose. For example, 400 cGy may cause a 30% incidence of sterility in young women, but in women aged above 40 years it results in 100% sterility. However, individuals of either sex show a degree of variation in their response to irradiation.
333 citations
TL;DR: Among the fecundity components examined here in noncontracepting populations, age at menarche and the duration of lactational amenorrhea appear to be the ones most affected by malnutrition.
Abstract: Moderate chronic malnutrition has only a minor effect on fecundity (reproductive capacity), and the resulting effect on fertility (actural reproduction) is very small. Among the fecundity components examined here in noncontracepting populations, age at menarche and the duration of lactational amenorrhea appear to be the ones most affected by malnutrition. But from neither of those effects can a difference in fertility of more than a few percent be expected between poorly and well-nourished women in developing countries.
300 citations
TL;DR: It is found that the reciprocal relationship between education and age at 1st birth is dominated by the effect from education to age at1st birth with only a trivial effect in the other direction.
Abstract: The interplay between education and fertility has a significant influence on the roles women occupy when in their life cycle they occupy these roles and the length of time spent in these roles. The overall inverse relationship between education and fertility is well known; but little is known about the theoretical and empirical basis of this relationship. This paper explores the theoretical linkages between education and fertility and examines the relationships between the 2 at 3 stages in the life cycle. It is found that the reciprocal relationship between education and age at 1st birth is dominated by the effect from education to age at 1st birth with only a trivial effect in the other direction. Once the process of childbearing has begun education has essentially no direct effect on fertility; but it has a large indirect effect through age at 1st birth. (Authors)
274 citations
TL;DR: The relatively low fertility expectations among those prevented from working by the unavailability of child care suggests that not just current employment, but also the intention of desire to work, is related to fertility behavior.
Abstract: This study examines the extent to which the unavailability of satisfactory child care is a constrait on employment for mothers with children under five years of age. It also explores some of the social and demographic correlates of constrait and the role child care plays in the relationship between labor-force participation and fertility. The analysis is based on data from the June 1977 Current Population Survey for the United States. A substantial minority of mothers with young children, both nonemployed and employed, feel that if child care were available at reasonable cost, they would seek employment or work more hours. Child-care constrait seems to be most prevalent among mothers who are young, black, single, with low education and with little income. The relatively low fertility expectations among those prevented from working by the unavailability of child care suggests that not just current employment, but also the intention of desire to work, is related to fertility behavior. The differential in bi...
162 citations
Journal Article•
TL;DR: Statistics of population dynamics in pre-fertility transition Europe, especially Western Europe, are diagrammed, tabulated, and graphed and new findings in the field indicate that the past was largely characterized by natural fertility.
Abstract: Statistics of population dynamics in pre-fertility transition Europe especially Western Europe are diagrammed tabulated and graphed. A description of new sources of information refined concepts on Europes fertility transition and ways of measuring the actual practice of family limitation are explained. New findings in the field indicate that the past was largely characterized by natural fertility. Factors such as the period of lactation and seasonal migration influenced total fertility differences. The transition from high to low fertility and mortality represented a shift from natural fertility to family limitation. Differences in the start and speed of the fertility decline are determined more by cultural than by socioeconomic conditions. This process began in Western Europe under varying socioeconomic conditions during the 1880-1910 period and was irreversible once it started. It is generally agreed that many areas of the developing world are currently undergoing a fertility transition. Both birth and death rates in these countries are higher than levels ever were in pre-transition Europe. However the new findings relating to the transition in Europe lead experts to believe that this curent transition will follow the same courese. A certain level of socioeconomic development is not a precondition. Family planning programs even in underdeveloped areas can be effective.
158 citations
TL;DR: An increased risk of unfavorable outcome of pregnancy was associated with DES exposure and among DES-exposed women who became pregnant, 81 per cent had at least one full-term live birth.
Abstract: Fertility and outcome of pregnancy were examined in women participating in the National Cooperative Diethylstilbestrol Adenosis (DESAD) Project. We compared 618 subjects who had prenatal exposure to DES with 618 control subjects. Fertility, measured in terms of pregnancies achieved, did not differ between the women exposed to DES and the controls. An increased risk of unfavorable outcome of pregnancy was associated with DES exposure (the relative risk of any unfavorable outcome of pregnancy was 1.69; P less than 0.001). Speculation on biologic mechanisms that might produce this difference is premature, since additional data about these subjects must be collected. Among DES-exposed women who became pregnant, 81 per cent had at least one full-term live birth.
149 citations
TL;DR: An alternative hypothesis that human females would fail to bear their optimal number of children without the pressure of mates and kin does appear possible, given the unique selection pressures generated by the rise of intelligence.
TL;DR: Fertility was, however, poor in one year following a rut which occurred in bad weather, and under the farm conditions there was no increase in fertility of hinds which had been barren the previous year above that expected from their body weight.
Abstract: The fertility of a stock of red deer kept under farming conditions on hill land over a period of 7 years has been assessed. The stock consisted of five cohorts of hinds born in successive years from 1971 to 1975. The fertility of hinds was related to their body weight by the general relationship P = 1 – exp(– 0·085(W– 52)) where Pis the probability that a hind will calve and W is her weight in kg at the time of the rut. When body weight was taken into account in this way, age had no effect on hind fertility. Fertility was, however, poor in one year following a rut which occurred in bad weather. Separation of calves from hinds at the time of the rut had no effect on fertility, and under the farm conditions there was no increase in fertility of hinds which had been barren the previous year above that expected from their body weight. Date of calving was slightly skewed, but 63 % of all calves were born in the first 20 days of June. Smaller hinds calved later; 1 kg body weight increased date of calving by about 0·3 days. Evidence of stag infertility was obtained and it was shown that one stag could effectively mate with 28 hinds such that they mostly calved within a 20-day period. It was possible to run 60 hinds with three stags and obtain calving rates which were similar to those for the hind population as a whole. There were no differences in fertility between matched groups of hinds exposed to one or two stags. The results are compared with those obtained by observation of wild stocks in Scotland.
TL;DR: The 1976 Pennsylvania school economic model of fertility behavior as discussed by the authors was proposed as an alternative to the "Chicago-Columbia" approach that dominates the current work on fertility economics, and the major thesis of the Pennsylvania model is that in order to understand the variety of real world fertility behavior models of fertility determination must be expanded to include: determinants of family preferences for consumption children and fertility regulation and factors related to the fecundity or reproductive capacity of women.
Abstract: This essay formally presents the 1976 Pennsylvania school economic model of fertility behavior. It is suggested as an alternative to the "Chicago-Columbia" approach that dominates the current work on fertility economics. The major thesis of the Pennsylvania model is that in order to understand the variety of real world fertility behavior models of fertility determination must be expanded to include: 1) determinants of family preferences for consumption children and fertility regulation and 2) factors related to the fecundity or reproductive capacity of women. A framework is proposed which emphasizes the role of interdependent preferences and it is considered necessary to distinguish between those who deliberately regulate their fertility and those who do not when estimating how income changes or birth control education programs will affect fertility decisions. Data is interpreted from lesser developed countries which indicates that often observed fertility is not a product of deliberate choice. For such countries time-series and cross-sectional fertility variations may reflect natural fertility determinants rather than desired family size. The authors claim that their framework more viably explains such problems as the postwar American baby boom and the variability of fertility in developing countries.
TL;DR: It is shown that when desired completed fertility undergoes swings, like those in the United States in recent decades, the turning points in period fertility will precede those in desired complete fertility by as much as five years and the amplitude of the swings inperiod fertility will be more than twice as great.
Abstract: Common sense suggests that changes over time in aggregate period fertility rates should be closely related to changes in desired completed fertility after controlling for contraceptive failure and desired spacing and timing; the nature of the relationship is however far from clear. This paper shows that when desired fertility undergoes swings like those in the United States in recent decades the turning points in period fertility will precede those in desired completed fertility by as much as 5 years and the amplitude of the swings in period fertility will be more than twice as great. Cumulated fertility on the other hand will lage behind reproductive goals. Period fertility rates will exceed desired completed fertility when desires are increasing and fall below it when desires are decreasing. These theoretical results help to explain some salient features of the American baby boom and bust. It is also shown that during a demographic transition period fertility will fall more rapidly than desired completed fertility and that towards the end of the transition period fertility will increase. (Authors)
TL;DR: Uterine involution appears not to be a barrier to fertility after 3 to 4 weeks postpartum in sows or 5 to 6 weeks post partum in cows and ewes unless delayed by inflammation or infection.
Abstract: An involuting uterus is a temporary barrier to fertility in cows, ewes and sows. Parturition is followed by a period when conception is not possible: about 1 week in sows and about 3 weeks in cows and ewes. Estrus and ovulation seldom occur together during this period and, if fertilization occurred and the embryo reached the uterus, placentation would be virtually impossible. The period of no fertility is followed by 2 to 3 weeks when fertility is possible, but not optimal. The extent to which the involuting uterus contributes to infertility during the second period is difficult to determine. Embryonic mortality in sows bred during this latter period appears to be a major cause of reduced litter size, so changes in uterine environment associated with involution may be essential for optimum fertility. Conception rate is lower up to 40 days after parturition than later in cows and ewes. Uterine involution appears not to be a barrier to fertility after 3 to 4 weeks postpartum in sows or 5 to 6 weeks postpartum in cows and ewes unless delayed by inflammation or infection.
TL;DR: In this article, the authors present a dynamic economic model of fertility behavior estimated with age-year-specific U.S. time-series data, showing that couples, on average, time their births to avoid periods when female wage rates are expected to be high, and that most of the observed effect of income and female wages on fertility rates is due to the indirect influence of these variables on couples' wage and income expectations.
Abstract: This paper presents a dynamic economic model of fertility behavior estimated with age-year-specific U.S. time-series data. The estimated model indicates that couples, on average, time their births to avoid periods when female wage rates are expected to be high, and that most of the observed effect of income and female wages on fertility rates is due to the indirect influence of these variables on couples' wage and income expectations. This paper also presents a decomposition of current fertility rates into timing and completed fertility components, allowing a comparison of current low fertility rates with couples' lifetime fertility plans. The estimates indicate that aggregate planned completed fertility is approximately equal to the fertility rate.
TL;DR: It is suggested that as the process of modernization begins, fertility-inhibiting factors such as these are weakened or altogether removed, before family planning is practised on any significant scale, and as a result, the natural fertility of these populations increases.
Abstract: Summary The fertility of pre-modern populations is subject to various inhibiting biological and behavioural factors. One such factor which ranks highly for its fecundity-inhibiting effect in practically all traditional societies, in prolonged breast-feeding. The post-natal abstinence associated with lactation, a widespread custom in tropical Africa, is believed to keep the actual childbearing performance of the populations of this part of the world well below their childbearing potential. Large-scale infertility of a pathological origin has been reported to be responsible for the unusually low birth rates observed among some populations not practising birth control, mostly in central Africa. It is suggested that as the process of modernization begins, fertility-inhibiting factors such as these are weakened or altogether removed, before family planning is practised on any significant scale, and as a result, the natural fertility of these populations increases. It is further postulated that the weakening of...
01 Jan 1980
TL;DR: The procedures described are applied to several different populations in order to illustrate the computational steps necessary to estimate the completeness of death records at ages above childhood in populations that are approximately stable.
Abstract: An elaboration of Prestons (Preston and Hill 1980) procedure for determining the completeness with which deaths are recorded in approximately stable populations is presented. Both the procedures of Preston and that of Brass are conventionally limited to mortality beyond early childhood to mortality above age 5 or age 10. The method considered here is based on characteristics of stable populations i.e. populations that have been subject for a long time to little variation in age-specific mortality schedules or in overall levels of fertility. The essential features of a stable population are maintained even if fertility has changed. This is the case as long as no strong trend in fertility existed more than 15 or 20 years before the date at which the population is observed. Recent changes in fertility may affect the structure of the population at adult ages but the effect on estimates of completeness of death records can generally be kept within tolerably narrow limits. Prior to showing how explicit estimates of the relative completeness of recording of numbers of deaths and persons can be derived from counts of deaths and persons by age it is noted that a life table for a stable population can be constructed directly from the recorded distribution of deaths by age or from the recorded distribution of persons. The procedures described are applied to several different populations in order to illustrate the computational steps necessary to estimate the completeness of death records at ages above childhood in populations that are approximately stable.
TL;DR: (1980).
Abstract: (1980). Studies on Fertility Traits in Swedish Dairy Cattle. Acta Agriculturae Scandinavica: Vol. 30, No. 2, pp. 109-124.
TL;DR: This article rigorously derives the properties of the regression of births on child deaths and shows 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.
Abstract: 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.
01 Jun 1980
TL;DR: A simple version of Easterlin's "synthesis framework" is presented, followed by a model of the interrelations of fertility and development (or modernization) that elaborates on the scheme initially advanced by Tabbarah.
Abstract: A simple version of Easterlins "synthesis framework" is presented followed by a model of the interrelations of fertility and development (or modernization) that elaborates on the scheme initially advanced by Tabbarah. A few empirical applications of the approach are also included. The framework of analysis is a modification of the usual economic theory of fertility in order to take fuller account of the theoretical and empirical work of demographers and sociologists. The determinants of fertility are seen as working through 1 or more of the following: 1) the demand for children--the number of surviving children parents would desire if there was no expense associated with fertility regulation; 2) the potential output of children--the number of surviving children parents would have if they did not deliberately limit fertility; and 3) the costs of fertility regulation including both psychic and objective costs. The role of these factors in determining actual fertility differs according to the comparative state of the potential output of and the demand for children. Among the complex of changes embraced by modernization several appear to be particularly important in bringing about the shift to modern conditions of childbearing. Historically these have been the following: innovations in public health and medical care; innovations in formal schooling and mass media; urbanization; the introduction of new goods; and per capita income growth. Presented in chart form is a summary view based on the framework sketched of the channels through which reproductive behavior is influenced by these various aspects of modernization. A schematic model of the impact of modernization on family reproductive behavior is presented.
01 Jan 1980
TL;DR: The use of the life table method for analyzing birth interval data was illustrated by applying the technique to data collected in the 1976 World Fertility Survey in Colombia as mentioned in this paper, which provided estimates of the proportion of women who moved on from 1 parity level to the next parity level during each successive 5 year period.
Abstract: The use of the life table method for analyzing birth interval data was illustrated by applying the technique to data collected in the 1976 World Fertility Survey in Colombia. The procedures involved in applying the techniques the major findings derived from the analysis of the Colombian data and the limitations of the method were described. This report is the 1st in a series of reports aimed at describing complicated statistical techniques which can be used to analyze in greater depth the results of World Fertility Surveys. Simple statistical techniques were inadequate for analyzing birth interval data due to the fact that many of the women included in the study had incomplete fertility at the time of the survey. Problems stemming from the incomplete nature of the fertility data were overcome by constructing separate life tables for each parity and age cohort subgroup in the survey population. The technique provided estimates of the proportion of women who moved on from 1 parity level to the next parity level during each successive 5 year period. The technique made it possible to accurately identify fertility trends over time and to assess the impact of various socioeconomic fertility differentials. Major findings were 1) the proportion of women moving from parity 3 to 4 4 to 5 and 5 to 6 within a 5 year period began to decline during the early 1960s; 2) the proportion of women moving from parity 2 to 3 began to decline in the late 1960s; 3) the proportion of women moving from parity 1 to 2 began to decline in the early 1970s; 4) the proportion of women giving birth to their 1st child during the 5 year period immediately following marriage remained at about 95% throughout the 1960s and 1970s; 5) fertility began to decline in the early 1960s among women who completed primary or secondary schooling in the late 1960s for women who had some primary schooling and in the early 1970s for women who had no schooling; 6) the death of a 1st child increased the proportion of women having a 2nd child within a 5-year period and reduced the average birth interval and similar effects were observed at each parity level; 7) breastfeeding tended to delay but did not prevent the next birth; and 8) contraceptive use reduced the proportion of women moving on to the next parity level during each 5-year period and increased the birth intervals.
TL;DR: C Cohort analysis shows that—although at lower levels—Jewish fertility has followed the general trends of American population.
Abstract: The 1971 National Jewish Population Survey provides cross-sectional data on achieved fertility, detailed birth histories, and other information on family formation for a countrywide representative sample of 5,303 ever-married women. Cohort analysis shows that—although at lower levels—Jewish fertility has followed the general trends of American population.
TL;DR: It is argued that the tendency of fertility levels to remain the same or even to rise in the short run should not necessarily be interpreted as the failure of such programs.
Abstract: Industrialization, urbanization, and other associated processes of modernization generally lead to a reduction of fertility through the practice of birth control (contraception and induced abortion) and delayed age at marriage. The evidence reviewed in this paper demonstrates that these same processes may also have some fertility-increasing effects. Birth rate data for a few countries in Latin America, Africa, and Asia clearly exhibit an increase in fertility in the early stages of modernization. Four factors related to modernization are found to have contributed more than others toward an increase in fertility: (1) earlier postpartum resumption of ovulation and menstruation as a result of decreased breast-feeding, (2) decline in the practice of postpartum abstinence, (3) reduction in the loss of reproductive performance of women caused by early widowhood, (4) reduction in the incidence of sterility as a result of the improved treatment of venereal diseases. Adequately nourished women have earlier menarch...
TL;DR: Four models are developed to describe the odds transformation of period- and age-specific fertility rates as products of age, period, and cohort effects for white U.S. women from 1920 to 1970, and it is shown that first differences are invariant in two-effect models, and second differences are Invariant in the three- effect models.
TL;DR: Female choice experiments were used to investigate the effect of relative male age on mating success and fertility with age and genotype in D. melanogaster, and the fertility of all males was found to increase with age.
Abstract: Female choice experiments were used to investigate the effect of relative male age on mating success in D. melanogaster. Experiments were conducted with a Canton-S (CS) strain, in which two virgin males of different ages (2, 4, or 8 days old) were offered to virgin females. Older males were found to be more successful under competitive conditions. In another group of experiments, vermilion (v) males of different ages competed with CS males of different ages. The competitive success of v males was found to increase with their relative age. Male fertility at 2, 4, and 8 days of age was documented for both male genotypes mated with CS females. CS males fathered more offspring per copulation than v males, and the fertility o fall males was found to increase with age. Discussion focuses on the changes in male mating success and fertility with age and genotype.
TL;DR: In this article, the authors examined the impact of parental economic status and family size on the actual and expected fertility of adult children using longitudinal data from two generations of families participating in the Panel Study of Income Dynamics.
Abstract: This paper examines the impact of parental economic status and family size on the actual and expected fertility of adult children using longitudinal data from two generations of families participating in the Panel Study of Income Dynamics. There was a modest positive relationship between first generation family size and second generation fertility. More importantly, the ideal family size of the parental family was more closely related to fertility behavior and plans in the second generation than was actual parental family size. In addition, the data revealed the hypothesized negative correlation between parental financial status and second generation fertility behavior and plans. Several mechanisms which could produce the correlation between parental characteristics and the fertility of their children are explored.
TL;DR: A simplified folk version of the Galenic-Islamic medical tradition furnishes Iranian provincial women with models for understanding conception, pregnancy, contraception, and the effects of the contraceptive pill on women's bodies.