Showing papers on "Fertility published in 1971"
Journal Article•
TL;DR: It is suggested that there may be 2 periods of life when a womens risk of breast tumor induction is particularly high the onset of puberty and the decade surrounding menopause.
Abstract: The city of Sao Paulo Brazil was included in an international collaborative study of the relationship of breast cancer risk to reproductive history and lactation experience. Data was obtained from interviews with 536 cases of the disease and 1550 controls drawn from women attending the same 7 hospitals and 2 clinics. Only women diagnosed during the 31 months ending June 1968 were included. Risk rose from 1.0 for women with no schooling to 1.8 for women with 8-11 years of schooling (p<.02). Among the 536 cases 77 were born in Europe. The expected number of cases among this group was 56.3 (p<.01). Duration of residence in Sao Paulo was not significant. Reproductive experience was recorded only for women who were or had been married -- a total of 459 patients and 1366 controls. Women who had a first pregnancy prior to age 20 had only about two-thirds the cancer risk of those whose first pregnancy occurred after age 25. This is thought to explain in part the decreasing cancer risk with increasing parity as women of high parity are likely to have had their first pregnancy prior to age 20. However significantly low risks are association with parity of 6 or more. This protective risk was conferred only to women under the age of 50. After age 50 increasing weight increased the risk. Lactation analysis is based on 410 cases and 1253 controls. No appreciable differences were noted between expected and observed numbers with different nursing experiences. Data suggest that women whose natural menopause is delayed to age 55 or later have about twice the breast cancer risk of women who undergo menopause prior to age 50. However artificial menopause prior to age 40 in the few patients recorded seemed to be correlated with fewer breast cancers. It is suggested that there may be 2 periods of life when a womens risk of breast tumor induction is particularly high the onset of puberty and the decade surrounding menopause.
132 citations
TL;DR: These facts take on added dimension when it is considered that certain differences by race in the roles of women would seem to encourage the lower fertility of black relative to white women.
Abstract: These facts take on added dimension when it is considered that certain differences by race in the roles of women would seem to encourage the lower fertility of black relative to white women.' One such difference is the greater participation of black women in the labor force. It has been argued that employment outside the home is an important stimulus for reducing desired family size.2 But, in the case of the blacks, if outside employment has influenced fertility desires, it has not succeeded in transforming desire into effective action. Another relevant difference by race in female roles is reflected in the higher rates of marital instability among blacks; black women are not as likely to be married for as long a period of time as are white women. This may restrict the fertility desires of black women, but it does not seem to play a major role in restricting their actual fertility. If black women have higher rates of labor force participation and marital instability than white women, why isn't their
96 citations
TL;DR: Data suggest that if sex-choosing were widely adopted initially 122 males would be born for every 100 females, which might lower the birthrate in countries where son survivorship is desired.
Abstract: The results of research regarding public knowledge and reactions about sex determination are reported. Ancient ideas and folklore are related. Because X sperm are heavier than Y sperm they can be separated by centrifuging. This has been shown to be effective in cattle breeding with insemination. Electrophoresis of rabbit semen has been used with insemination and correct prediction of sex in a large proportion of cases. Human sperm can also be separated by this technique. In vitro separation followed by artificial insemination seems to be the only promising method for the near future. Use of alkaline douches after intercourse to select against X sperm has not been successful. Shortly after ovulation the ova is high in the fallopian tube. As Y sperm are thought to move faster than X sperm intercourse soon after ovulation has been recommended as giving a greater chance for female offspring. Problems are likely to arise if successful control of sex determination becomes practical. There is a preference for male babies in many diverse cultures throughout the world. Preference for at least 1 child of each sex has been reported to have had a significant influence in determining whether those with children want to have an additional child. A questionnaire related to the subject was distributed to 438 students at 3 Florida colleges. Of these 283 (64%) were returned. Of these a large majority preferred male over female children especially for the 1st child. For the 2nd child more wanted a girl if the 1st was a boy. Attitudes toward sex determination were unrelated to fathers occupation or parents education. Black and male respondents favored sex-choosing more than did white female respondents. Catholics were more often opposed to the innovation of sex determination. Those listed as having no religion had the most favorable attitudes. Data suggest that if sex-choosing were widely adopted initially 122 males would be born for every 100 females. Sex-choosing might lower the birthrate in countries where son survivorship is desired.
89 citations
TL;DR: Large scale data with refined measures of socioeconomic status and race were used and it was concluded that no clear causal relationships can be demonstrated since all the "effects" are statistical associations.
Abstract: Large scale data (The Collaborative Study) with refined measures of socioeconomic status were used to test the hypothesis that socioeconomic status and live birth sex ratio are positively associated. 3 controlled factors were analysed: socioeconomic status gravidity and race: the Mantel and Haenszel procedure was used. The sex ratio was positively and significantly (p less than .015) related to the socioeconomic index. Gravidity appeared to have no significant effect on sex ratio. Race was significantly related (p less than .04) with Negroes and Puerto Ricans having 6% and 7% lower ratios than whites. The influence of the socioeconomic factor was greatest among Negroes and Puerto Ricans. Between the lowest and highest socioeconomic categories the odds for a male birth increase 8 to 9%; however there is a slight decrease in male child odds between the 2 highest socioeconomic classes suggesting the greatest influence of socioeconomic factor is among the lower socioeconomic groups especially for Negroes and Puerto Ricans. It is concluded that no clear causal relationships can be demonstrated since all the "effects" are statistical associations.
83 citations
TL;DR: A decline in illegitimate fertility commenced in most countries in the last quarter of the nineteenth century, and was arrested in the 1920's and 1930's, until non-marital fertility had been cut in half.
Abstract: Between 1880 and 1940, to take approximate dates, illegitimate fertility rates in Europe dropped precipitously, falling in most countries by 50% or more. The rates used throughout this paper relate extra-marital births to the number of unmarried (i.e. single, widowed and divorced) women; we use a standardized index, I {ih} to be discussed later. In Fig. 1 we present most of the European series of I h 's that can be computed from existing census and vital registration data. Although there are interesting exceptions the general picture is clear: a decline in illegitimate fertility commenced in most countries in the last quarter of the nineteenth century, and was arrested in the 1920's and 1930's. Once it had begun in a country, the downward course was swift and uninterrupted, until non-marital fertility had been cut in half.
83 citations
TL;DR: In the early 1800s fertility was lower in the older settled areas of the East than in those undergoing settlement; and within every division urban fertility is lower than rural fertility as discussed by the authors.
Abstract: Both theory and empirical research on historical American fertility suggest that human fertility responds of voluntarily to environmental co nditions. In the economic theory of fertility tastes prices and inco me determine the optimal number of children. These influences lead to the expectation of the following ordering of areas from high to low fertility at any given time: frontier settled agricultural new urban areas and old urban areas. Over time it can be expected that fertility would decline as new areas "age" e.g. frontier areas become settled agriculture and new urban areas become old urban areas. These expectations are supported by the available evidence. In the early 1800s fertility was lower in the older settled areas of the East than in those undergoing settlement; and within every division urban fertility is lower than rural fertility. The American fertility decline reflects not only the processes of urbanization and industrialization but that of settlement as well. The problem is whether the voluntary response of fertility to environmental pressures results in a socially optimal adjustment.
83 citations
TL;DR: The effect of time after insemination on fertility and embryonic loss has been studied for each day’s egg production by direct observation of chicken eggs after 18 days of incubation, showing a significant initial increase in fertility with sperm storage from day I (first day of fertileeggs) to day 3, followed by a few days of high fertility which was then followedby a linear decline through 18 days.
Abstract: The effectof time after insemination on fertility and embryonic loss has been studied for each day’s egg production (60-150 eggs per day) by direct observation of chicken eggs after 18 days of incubation, The resultsshowed a significantinitialincrease in fertilitywith sperm storage from day I (firstday of fertileeggs) to day 3, followed by a few days of high fertility which was then followed by a linear decline through 18 days. Embryonic death was higher initially,reduced to a minimum when fertility was maximum, and increased linearly with increasing age of spermatozoa until fertilitywas reduced to a low level. The effect on fertilityand embryonic loss was influenced significantlyby both the male and female as well as time after insemination, and embryonic loss was negatively related to fertilitylevel of the male. That embryos die at an earlierage due to fertilizationby aged sperm wa s not conclusively confirmed in this study.
78 citations
01 Oct 1971
76 citations
TL;DR: Findings show that high rates of female labor force participation outside the home and low rates of economic activity of children depress a society’s fertility level, as measured by the crude birth rate or the child-woman ratio.
Abstract: This study empirically investigates the relationship between the economic structure of populations and their level of fertility, using data from censuses recently conducted in some 50 nations. Findings show that high rates of female labor force participation outside the home and low rates of economic activity of children depress a society’s fertility level, as measured by the crude birth rate or the child-woman ratio. It is also hypothesized, but not confirmed, that the per cent of unpaid family workers in a society is positively related to its fertility level. A model is presented that treats these three components of economic structure as intervening variables through which the exogenous variables, urbanization, industrialization, and education, operate in influencing the fertility level of a society.
74 citations
70 citations
Journal Article•
TL;DR: In this paper, the authors proposed an alternative approach to the demographic transition theory, which analyzes with the help of empircal data certain key demographic variables and shows how fertility trends are determined by the way these key variables are affected by the development process.
Abstract: This discussion offers an alternative approach to the demographic transition theory. It analyzes with the help of empircal data certain key demographic variables and shows how fertility trends are determined by the way these key variables are affected by the development process. The result is general guidelines for population projections and population policy as well as for the nature of research required for their support. 4 main variables are defined and estimated i.e. R the average effective span of female reproduction (between the average age at marriage of females and age 45); P the probability of survival of a live birth to the age of maturity say 20 years; C the average number of children desired by married couples in their completed family; and Sn the average natural spacing of live births of ever married women during the period R. A table presents the likely ranges of desired number of children (C) and maximum number of children (M) in different regions: Black Africa; North Africa and Asia; Korea and Taiwan; and Western Europe and North America. In Black Africa where C exceeds M couples generally desire a larger number of chidlren than they can possibly achieve even without the use of birth control. Couples want to space their live births at shorter intervals than the natural spacing interval. Since natural spacing is determined mainly by biological factors fertility in Black Africa may be deemed to be basically a "biological" phenomenon. In the industrialized countries of Western Europe and North America C is less than M and desired spacing exceeds natural spacing. Couples want to achieve a spacing interval larger than natural spacing and can only do so by the proper use of birth control. Spacing will tend to be equal to the desired spacing interval and a change in natural spacing or natural fertility will have no significant effect on actual spacing and fertility. As C is admittedly determined by social economic and psychological factors fertility in the industrialized countries may be said to be a "socioeconomic" phenomenon. Between these 2 limiting situations e.g. in North Africa and Asia C may be larger than M for some of the couples and smaller than M for others the difference between countries or areas being largely in the proportion of the population in each of these 2 categories. Fertility in these countries is in part biological and in part socioeconomic. According to this model population projections in developing countries should make provision for the possiblity of rising fertility.
Journal Article•
TL;DR: In this paper, the authors reported the second case of a fertile female with a 45,X karyotype and the possibility of mosaicism cannot be dismissed, although in two different tissues the karyotypes is consistently 45, X.
Abstract: We have reported the second case of a fertile female with a 45,X karyotype. The possibility of mosaicism cannot be dismissed, although in two different tissues the karyotype is consistently 45,X. Her normal daughter has a 46,XX karyotype.
TL;DR: In this paper, seasonal variation in the number of live births in the United States increased in amplitude during the 1940's, remained high throughout the 1950's, and then declined again.
Journal Article•
TL;DR: In this article, the authors reported the second case of a fertile female with a 45,X karyotype and the possibility of mosaicism cannot be dismissed, although in two different tissues the karyotypes is consistently 45, X.
Abstract: We have reported the second case of a fertile female with a 45,X karyotype. The possibility of mosaicism cannot be dismissed, although in two different tissues the karyotype is consistently 45,X. Her normal daughter has a 46,XX karyotype.
TL;DR: Analysis supports the hypotheses that industrialization influences fertility through shifts in the social status of women, both in their work and at home, and reveals that smaller family size is associated with generally higher levels of status among women.
Abstract: This paper addresses itself to some linkages between macro-social structure (industrialization, social class), social psychological variables (husband-wife decision making), psychological variables (attitudes), and fertility. A total of 726 currently mated women with proven fertility in five Brazilian communities were interviewed to determine various attitudes, their work experience, their participation in family decisions, their fertility ideals, and actual fertility. The five communities were selected along a rural-urban-industrialization continuum to include a village, two non-industrial cities, and two industrial cities (one of which was Sao Paulo). Family size in the industrial cities was small in all social strata, while in the non-industrial cities family size was large in the lower strata and declined in the upper strata. Further analysis revealed that smaller family size is associated with generally higher levels of status among women—higher educational levels, greater social contacts and more skilled employment, and equality in family decision making. Our analysis supports the hypotheses that industrialization influences fertility through shifts in the social status of women, both in their work and at home. New education and work opportunities facilitate the emergence of modern conceptions of the role of women in society and egalitarian decision making in the family. These attitudes and patterns of husband-wife interaction are related to smaller family size ideals and lower fertility.
TL;DR: Under the limited conditions of this study, there is some indication that the intrinsic rate of natural increase may be a reliable method for differentiating 2 species of Trichogramma.
Abstract: Studies on life and fertility tables were undertaken with Trichogramma pretiosum Riley (uniparental race) and T. retorridum Girault to explore the potential for using the intrinsic rate of natural increase (r) as a method for differentiating races and/or species of Trichogramma . The r value of the uniparental stock did not differ greatly from the corresponding value of 5 of its clones. These clones were selected on the basis of different adult longevities. However, each of these 6 values of r was consistently greater than the r of T. retorridum . Under the limited conditions of this study, there is some indication that the intrinsic rate of natural increase may be a reliable method for differentiating 2 species of Trichogramma . Other studies were conducted with T. pretiosum to determine the repeatability of r and of its component variables. Variation in mean fertility of T. pretiosum was not significant when host eggs were presented to females 1 day old or younger. However, the mean fertility of this parasite decreased significantly if females did not have the opportunity to lay eggs in the 1st 2 days. Adult fertility varied greatly within the uniparental race of T. pretiosum . The mean fertility of the parental line was significantly lower than that of any one of its 5 clones tested. Significantly high variation in mean fertility was also found between the 5 clones. A high adult density corresponded to a low mean fertility of the progeny, and vice versa.
TL;DR: Using equations derived from the cross-section study and time-series data for five European countries during the period that their fertility rates fell, it is shown that predictions about past fertility changes are in error and suggest caution in the use of cross- section relations to predict the course of fertility in developing countries.
Abstract: Recent studies by Adelman and by Friedlander and Silver, which have investigated whether regression equations derived from cross-section data can be used to predict the impact of socioeconomic development on changing levels of fertility, are reviewed critically. Regression analyses based on data for 57 countries c. 1960 show that fertility (gross reproduction rate) varies cross-sectionally with region as well as with level of development (as measured by per capita income, percent labor force in primary sector, expectation of life, illiteracy rate). Using equations derived from the cross-section study and time-series data for five European countries during the period that their fertility rates fell, it is shown that predictions about past fertility changes are in error. The results suggest caution in the use of cross-section relations to predict the course of fertility in developing countries.
TL;DR: This analysis tries to analyse the impact of nuptiality on the fertility and growth of a series of populations from developing nations where extra-marital fertility is negligible.
Abstract: In the European historical experience, nuptiality patterns played a very significant role in the development of low fertility. Late marriage and widespread celibacy provided one of the mechanisms by which age-specific fertility rates were brought to low levels in the populations of Western Europe. In Eastern and Central Europe on the other hand, where marriage customarily occurred earlier and was more nearly universal, a somewhat slower fertility transition was achieved through a reduction in marital fertility — without any drastic accompanying nuptiality change. Populations of developing countries, however, commonly exhibit nuptiality patterns characterized by a still higher incidence and a considerably younger age-pattern of marriage than even the earliest observed schedule from Eastern Europe. With few exceptions, little work has been done to date to examine the implications of these very early and universal marriage schedules for fertility in general and for the growth of these populations in...
TL;DR: The hypothesis that polygyny is associated with higher fertility than monogamy was evaluated and revealed that the fertility rate was higher for polygynous married women; however, when marriage duration was controlled, there was no significant differences between the fertility rates observed for the polygynously and monogamously married women living in rural areas nor those living in urban area.
Abstract: The hypothesis that polygyny is associated with higher fertility than monogamy was evaluated. An assessment of previous studies and of the results of a 1966-1967 study comparing the fertility levels of polygynously and monogamously married women in a rural and an urban population in Nigeria lead to the conclusion that the hypothesis was useless. The hypothesis was judged to be useless because 1) fertility rates are the product of multiple influences; 2) it is too difficult to separate out these multiple influences given the variability involved in polygynous practices and the inadequates of the data; and 3) the influence of polygyny on fertility is too slight to take into account. In the Nigerian study the fertility of 2742 monogamously married women was compared with the fertility of 1261 polygynously married women. Preliminary analysis revealed that the fertility rate was higher for polygynously married women; however when marriage duration was controlled there was no significant differences between the fertility rates observed for the polygynously and monogamously married women living in rural areas nor those living in urban area.
TL;DR: The broad conclusion is that while couples no doubt do consider income, employment opportunities, etc. in deciding how many children to have, such considerations have had a relatively minor influence on changes in fertility, which for the most part have been the result of changes in attitudes.
Abstract: It is widely assumed that fertility varies positively with economic conditions. Actually this assumption receives little support from the historical record. For a century before 1930 fertility declined while the economy expanded and real incomes rose. Then for nearly three decades fertility and incomes fell and rose together. Since 1960 they have again moved in opposite directions. Clearly, no simple generalization about their relation will hold water. More sophisticated explanations are based on relative rather than absolute incomes. Banks suggested that the downturn in English fertility in the 1870's might have occurred because standards of middle-class consumption rose faster than middle-class incomes, but he found the evidence inconclusive. To reconcile the post-war baby boom in the United States with earlier experience, Easterlin has argued that fertility is determined by the relationship between the income of couples in their twenties and the income of their parents ten to fifteen years ear...