Drop In Fertility Research Articles

Has a fertility transition begun in West Africa?

AbstractThis paper examines changing patterns of reproduction in two West African countries, Senegal and Ghana, which conducted both World Fertility Survey and Demographic and Health Survey enquiries. It aims to estimate fertility levels and trends in these countries, examine how changes in marriage, contraceptive use, breastfeeding and post‐partum abstinence are affecting family building patterns and discuss whether a fertility transition has begun. While fertility remains high in both Senegal and Ghana, it has begun to decline. In Ghana, the drop in fertility commenced in the late 1960s but has slowed recently. In Senegal, fertility decline began a decade later but is now more rapid. With these declines, residential and educational differentials in fertility have widened, particularly in Senegal. Both rises in ages at marriage and increases in the use of contraception have contributed to the fall in fertility. However, most women of high socieconomic status still want four or live children. Other women want even more. Although a transition to the control of fertility by contraceptive means has begun, the transition to low fertility may progress slowly.

To Sow One Acre More: Childbearing and Farm Productivity in the Antebellum North

Children supplied valuable labour on 19th-century American farms. But the value of that labour varied, and the children themselves represented economic costs as well as benefits. How did children affect a farmer's choices? Did bigger farms mean, in effect, bigger families? Drawing on census, wage and other data, Craig addresses such questions in offering a new econometric interpretation of productivity and fertility in the antebellum North. Craig argues that children did not provide a noteworthy advantage on the frontier, though they did in the settled but rocky-soiled Northeast. He concludes that a farmer's economic strategy depended not so much on the size of this holding or his age (and fertility), as it did on regional agricultural patterns and proximity to market. These findings contradict the now dominant view that farmers adjusted output according to the number of available labourers - including children. Distinguishing between the Northeast and Old Northwest, Craig constructs a model that incorporates both the advantages and monetary disadvantages of child labour, and accounts for the drop in fertility in regions where opportunities for children off the farm were greater than those at home.

Fertility Transition in Syria: From Implicit Population Policy to Explicit Economic Crisis

The 1960 census revealed that Syrias population had increased from 2.9 million in 1947 to 4.2 million in 1960 and it was growing at an annual rate of 26 persons/1000 population. In 1970 when the population reached 6.3 million pronatalist officials began to be concerned because forecasts indicated that by 1990 the population would reach 12.8 million and the high growth rate would threaten the countrys economic and educational development plans. Yet it was not until 1993 that the government took measures to curb population growth by population education mandatory school attendance for both girls and boys and encouragement of later marriage age. The total fertility rate still increased to 6.6 children in 1981 from 4.9 in 1960 because of the improving socioeconomic situation the decline of child mortality and the improved survival of female children. Subsequently in the 1980s womens status and their literacy rate also improved while their labor force participation rapidly increased accompanied by a rapid decline of the birth rate that began in 1986. For recent generations the average number of births among working women was 32% lower than the number among nonworking women. The demographic turning point occurred when the crude birth rate fell by 26% between 1985 and 1990. Contraceptives were made available in pharmacies and family planning programs registered an 11-fold increase in the number of visits between 1983 and 1988 and a 7-fold increase in the number of new users. However 1982 ushered in a period of economic decline after a decade of prosperity as fees for oil exports and transit duties fell in the wake of the drop in oil prices. As a result the proportion of women who were employed rose from 7.9% in 1981 to 12.2% in 1989 because of the necessity to counter heavier taxation. In sum the economic social and educational factors accounted for the drop in fertility but the full integration of women into the labor market still awaits policy decision.

Fertility in Italy and Spain: The Lowest in the World

A t the beginning of the 1990s, the over 100 million inhabitants of Italy, Spain and Portugal were reproducing at the slowest rate of any large population in the world; the period total fertility rate (TFR) for 1989-1990 was just 1.3-1.4 lifetime births per woman. The 1990 crop of 1.1 million babies born in the Italian and Iberian peninsulas was 26% smaller than that born in France and England, which have the same combined total population. This comment describes and compares fertility trends in Italy and Spain and speculates on the causes of the exceptionally low fertility in these two countries, which have been known for the central role children play in family and society. Contrary to popular belief, Italy and Spain have never had very high levels of fertility. Around 1860 or 1870 (before the onset of the modern fertility transition), levels of fertility among Italian and Spanish women were lower than those among German, Dutch or Belgian women, and were about the same as those of English, Danish and Swedish women.* Nonetheless, 19th-century travelers and observers from Northern Europe mistook the noisy presence of children in the streets, the attention they received from parents and adults, and the active role they took in many rural and urban occupations as signs of unusually high fertility. The data, however, prove otherwise. As Table 1 shows, fertility decline had been firmly established in Italy and Spain by the end of World War I; in fact, fertility control had already been practiced for half a century in many regions. Using the standard definition that a 10% drop in fertility from stable pretransition rates signals that a decline is underway, the beginnings

Family Dynamics in China: A Life Table Analysis.

This text establishes three major milestones in demography. It provides the first English-language demographic profile by a Chinese author of contemporary population trends and family dynamics in China: it constructs a viable mathematical model for extending existing family-status life table models to the three-generational family that is still common in and the rest of Asia: and it uses that model to compare the dynamics of family structure in before and after the dramatic drop in fertility that followed the 1979 implementation of stringent family size limits. 20 percent of the world's population lives in the People's Republic of yet relatively little has been known about its population structure. The 1982 census of population, the first in to use sophisticated techniques of data collection and analysis, made it possible to examine family characteristics and their determinants: marriage, widowhood, and divorce: fertility and mortality: and rural-urban, ethic, and regional differences. Family Dynamics in China draws on both the 1982 census and other demographic data collected during the 1980's. This general analysis provides the framework for a mathematical model that uses its starting point family-status life table models, developed by Bongaarts and others, that simultaneously include multiple variables such as age, marital status, parity, and fecundity. These models have been based upon the nuclear family and have assumed tht adult children necessarily leave theri parents' homes at marriage. Yet the 1982 Chinese census indicated that nearly 20 percent of all Chinese families contained three or more generations. By extending existing models to accommodate the multigenerational family. Yeng Yi has made an important methodological advance that is applicable to many other non-Western societies. In the last part of Family Dynamics in China, this new model is systematically applied to analyzing the dramatic decline in fertility in since 1979. Yeng Yi compares conditions from 1950 to 1970 with those now unfolding. What are the effects of the decline in fertility upon family size and structure, and upon the family life course of women, in particular?. How many years will be spent caring for children, how many for the elderly parents: what is the overlap-the period of overload when families may be caring for both?. As family size diminishes, for example, the proportion of elderly, particularly women, who have no surviving children is risking, especially in the cities. What are the likely social consequences of this in a society where the multigenerational family remains the primary social support system for the elderly?.

Momentum and the growth-free segment of a population

In the scenario of a sudden drop in fertility to replacement level. Preston (1986) argued that the population segment under age T, the length of generation, remained growth-free. Here we first present a new relationship for the momentum of any observed population as the ratio of 1) the proportion of the observed population under the mean age at childbearing to 2) the proportion of its life table population under that mean age. We then use that relationship to demonstrate Preston's approximation. Growth factors for other population segments are also presented. When the initial population is stable, momentum can be approximated as a function of the net reproduction rate alone.

Demography and Degeneration: Eugenics and the Declining Birthrate in Twentieth-Century Britain

Richard Soloway offers a compelling and authoritative study of relationship of eugenics movement to dramatic decline in birthrate and family size in twentieth-century Britain. Working in a tradition of hereditarian determinism which held fast to premise that like tends to beget like, eugenicists developed and promoted a theory of biosocial engineering through selective reproduction. Soloway shows that appeal of eugenics to middle and upper classes of British society was closely linked to recurring concerns about relentless drop in fertility and rapid spread of birth control practices from 1870s to World War II. Demography and Degeneration considers how differing scientific and pseudoscientific theories of biological inheritance became popularized and enmeshed in prolonged, often contentious national debate about race suicide and the dwindling family. Demographic statistics demonstrated that birthrates were declining among better-educated, most successful classes while they remained high for poorest, least-educated portion of population. For many people steeped in ideas of social Darwinism, eugenicist theories made this decline all more alarming: they feared that falling birthrates among better classes signfied a racial decline and degeneration that might prevent Britain from successfully negotiating myriad competive challenges facing nation in twentieth century. Although organized eugenics movement remained small and elitist throughout most of its history, this study demonstrates how pervasive eugenic assumptions were in middle and upper reaches of British society, at least until World War II. It also traces important role of eugenics in emergence of modern family planning movement and formulation of population policies in interwar years.

Pratiques successorales et fécondité : l'effet du Code civil

Inheritance Practices and Fertility: the Effect of the Civil Code, by Paul-André Rosental. The Civil code has often been blamed for having caused a drop in 19th century France's fertility rate. By stipulating that estates had to be divided up equally among heirs rather than leaving fathers free to decide who they wanted to bequeath their property to , it may be responsible for testators' decisions to have less children so as to avoid estate division. Despite their shortcomings, the data gathered by historians over the past twenty years make it possible to conduct an informal test on this hypothesis. Only one-half of France experienced a change in estate law in 1804, which, in this area, had an overall dampening, but complex and unstable effect on fertility. The rate of the drop in fertility depended, in particular, on how much property was owned in each region as well as on a family's influence and ability to convince heirs remembered unfavourably to waive their rights.

Population Change in a Rural Area of Bangladesh, 1967-87

The Matlab subdistrict of Bangladesh is unique in the developing world in the extent of demographic data available over a long time period, during which a serious famine occurred and a family planning program that employed village women as home visitors was introduced within the context of maternal and child health services. These data demonstrate that fertility in this population is well below the maximum biologically feasible, primarily due to the long and intense breast-feeding practiced, that seasonality of births is pronounced, and that fertility drops in response to drastic food shortage. Sex differences in mortality favor males, but during famine the disparity was reduced. Despite arguments that family planning programs are ineffective and use resources that could be applied in areas more relevant to development, the Matlab family planning program has led to both reduced fertility and reduced mortality and may be changing the status and roles of women.

A cost of mating in female fruitflies

COSTS of reproduction occur when an increase in reproductive rate reduces future reproduction by increasing mortality or reducing fertility. Such costs have been demonstrated in plants and animals in laboratory and field studies1–5. Their importance lies in their possible role in the evolution of life histories and of senescence6–15. An understanding of their mechanisms will also reveal the nature of the physiological constraints on longevity and fertility. Most accounts assume that these occur as a result of competition for nutrient allocation between growth, storage, somatic maintenance and reproduction16–21. An increase in reproductive rate would then result in a denial of nutrients to other processes, resulting in a drop in life expectancy or future fertility. Some support for this point of view comes from the finding that lifespan is lengthened in female Drosophila melanogaster that have inactive or absent ovaries22–23 or that are experimentally induced to produce fewer eggs24. Increased exposure to males, however, also results in a drop in lifespan24–26. We show here that mating with males greatly reduces lifespan in female fruitflies whose rates of egg-production and egg-fertility do not differ, suggesting both that simple nutrient allocation to reproduction is not its only physiological cost, and that males can cause females to remate at a frequency that results in reduced female lifetime reproductive success.

La transition démographique en Chine populaire et à Taiwan

Demographic changes in the People's Republic of China. Two populations of widely different size (less than 20 millions inhabitants iiTthe one case, and in the other over 1,000 million in 1985), sharing the same ethnic traditions of fertility, exposed to very different political, social and economic conditions, have both recently witnessed a spectacular drop in their birthrate. This decline, although more publicized in China, has been even more marked in Taiwan, where the natural rate of growth thirty years ago was much higher (almost 3,7 % in 1955-56 compared with 2 % in China) because of an earlier decline in mortality. The drop in fertility also occurred earlier in Taiwan, and developed along more consistent lines than in Mainland China. In addition, the trend has been spread more widely among different social classes and geographical regions, without giving rise to the kind of tragedies which the official press in China itself deplores. The contrast has less to do with difference in political regimes than with the very uneven scale of socio-political changes ; it is the latter which are basically responsible for the drop in fertility noted in Taiwan, whereas in People's Republic of China the same phenomenon, particularly marked after 1970 owes much less to a « modernization » which is yet to come, than to the very strict policy on birthcontrol which is being implemented.

Age-related reproductive decline in the male Japanese quail

A series of experiments was conducted to study the decline in reproduction associated with age in the male Japanese quail. In Experiment 1, eggs were collected from pairs that were 28, 56, 107, and 149 weeks of age. Pairs that were 56 weeks of age or older showed a sharp drop in fertility and hatchability. Subsequent experiments were designed to study the endocrine and behavioral basis for this decline in the male. In Experiment 2, males that were between 23 and 70 weeks of age were tested for mating behavior, plasma testosterone was measured, and testes wet weight was determined. There were no significant differences between the age groups. However, samples taken from an additional group of males 168 weeks of age showed significantly ( P < 0.05) lower serum testosterone and testes weight. Therefore, the third experiment was designed to include age groups of males between 4 and 126 weeks of age in order to further examine this decline in males older than 70 weeks of age. There was a significant ( P < 0.05) drop in this number of males showing sexual behavior and of those males showing sexual behavior; the quantity of mating activity also declined. Plasma testosterone was reduced in the older groups; however, the change was not significant. In addition, the size of the cloacal gland, an androgen-dependent organ, declined with age ( P < 0.05). These results argue that the age-related reproductive decline may have behavioral as well as endocrine basis. Possibly, the behavioral changes may result from altered receptor sensitivity at the level of areas of the brain, which control reproductive behavior, and at the level of the testes, which affect hormone production and spermatogenesis.

Glacial–Holocene transition in deep-sea sediments: manganese-spike in the east-eqautorial Pacific

Over large areas of the tropical Pacific, calcareous sediments show one or more dark-coloured manganese-rich layers within the uppermost 40 cm of the record1,2. In the east-equatorial Pacific two layers are strongly developed, with the upper one appearing as a double layer in places. We report here that the lower layer is centred on the glacial–Holocene boundary, and we present evidence that its origin is tied to a pronounced drop in fertility of the ocean. Such a fertility decrease is implicit in a weakening of east-equatorial upwelling systems3,4. If real, it has important ramifications for the history of oceanic (and atmospheric) chemistry.

Deglacial CO 2 buildup: Constraints on the coral-reef model

The coral-reef hypothesis of degalcial CO 2 buildup in the atmosphere can account for about one-half of the signal seen in ice cores, assuming additional coral-reef growth releases 2 atmospheric carbon masses (ACM). The carbonate dissolution signal on the deep sea floor suggest titration of only 1 ACM. At least 4 ACM of CO 2 must be made available to satisfy the requirements of pCO 2-increases, growth of biosphere and of sedimentary carbon pool, carbonate dissolution on the sea floor, and saturation of newly introduced meltwater. A drop in ocean fertility is called for to provide the missing CO 2. Such a drop is evident in deep-sea cores from the western equatorial Pacific. CO 2 buildup appears to occur as a step, near 13,500 years B.P. Dissolution on the deep sea floor begins near 11,000 years B.P. The difference of 2500 years may describe a mixing lag due to meltwater input (the “Worthington Effect”).

Glacial-Holocene Transition in Deep-Sea Carbonates: Selective Dissolution and the Stable Isotope Signal

The oxygen and carbon isotopic signals of planktonic Foraminifera from closely spaced samples from two box cores taken in the western equatorial Pacific change through the glacial-to-Holocene transition as a result of several factors, one of which is the Holocene dissolution pulse starting about 12,000 years ago and reaching full force shortly after. The onset of dissolution comes shortly after the maximum rate of deglaciation but well before the maximum drop in fertility in upper waters. The effect of dissolution is 20 to 30 percent of the amplitude of isotopic change in Globigerinoides sacculifer, at the depth of the present lysocline.

Compulsory sterilization: the change in India's population policy.

Indias official advocacy of compulsory sterilization has caused dismay among those who think voluntary birth control services were never provided on a mass scale and that compulsory measures will cause resistance to family planning in general but it has also brought relief to those who felt Indias stand at the World Population Conference in 1972 was not nearly antinatalist enough. The new policy is in effect an admission that education and economic development will not bring about a drop in fertility soon enough. The timing of the policy shift can be explained by the state of emergency declared in June 1975. Prior to that it would have been politically impossible for Mrs. Gandhi to make any strong statements in favor of birth control. Since the family planning programs inception in 1952 sterilization has been an important part and incidence increased significantly every year until 1974 when budget cuts did not allow for program expansion. There are various possible explanations for the governments rethinking of its priorities but what was clear was that there was no clamor from the people to reinstate the services. The motivation to have small families seemed to be lacking perhaps because it is connected to a certain socioeconomic threshhold which had not been reached by the populace when the focus shifted from sterilization to economic development as the best contraceptive. The 5 states that appear to have had a significant decline in fertility have also done well in economic development while the family planning performance of the poorest states Bihar and Uttar Pradesh has been dismal. The problem of motivation is further complicated by a tradition and culture that require large families. The current population contains a huge growth potential for the future; all projections of the population show substantial increases. The Chinese example in family planning cannot be followed without fundamentally changing the structure of the entire economic and political system. Only the most economically prosperous states have the personnel and facilities to enforce a compulsory sterilization law. 1 of those Maharashtra is on the point of passing such a law. The experience of the state will be important for future consideration of compulsory sterilization nationwide.

Fertility Drops in Four Large Developing Nations Even Prior to Advances in Economic Development

Fertility Drops in Four Large Developing Nations Even Prior to Advances in Economic Development

Chemosterilant as a booby-trapping agent for the Queensland fruit fly, Dacus tryoni

Females of Dacus tryoni, booby-trapped by topical application of 400 µg of N,N'-tetramethylenebis( 1-aziridinecarboxamide), sterilized males with which they copulated. Sterility in the males was complete and persisted for at least 10 days after mating contact. Booby-trapped females were less attractive to males than untreated females when the sterilant was applied before the flies reached sexual maturity. Attractiveness was not significantly impaired when the females were treated after reaching sexual maturity. Sterile males were as effective as fertile males in winning mates. The introduction of a small proportion (one-tenth) of booby-trapped females into a cage population caused a considerable drop in overall fertility, but the sterilant was probably spread more by attempted matings rather than by actual copulation.

Population control in the Australian sheep blowfly, Lucilia cuprina, by the release of female-borne chemosterilant. I. Female to male transfer of chemosterilant during mating

N,N'-tetramethylene-bis-(1-aziridinecarboxamide), applied topically, sterilized male and female Lucilia cuprina (Wiedemann) at a dose of 10 µg per fly. Females tolerated 800 µg per fly. A female 'booby-trapped' with 400 µg of sterilant could transfer a sterilizing dose to a male during copulation. Booby-trapped females were sexually attractive and sterile males were as sexually vigorous as fertile males. The introduction of either booby-trapped females or sterilized males into cage populations caused a greater drop in fertility than expected, but the effect was probably due more to unspecific contact between flies than to mating contacts.

The Effects of Isoimmunization with Semen , on Fertility in the Turkey Hen

INTRODUCTIONMANY studies in mammalian species have shown a relationship between infertility and anti-sperm antibodies, but many others have not. This area of investigation has been reviewed by Tyler (1961) and Cohen (1969). McCartney (1923) reported that a single injection of fowl testes induced sterility in four chicken hens. However, Lamoreux (1940) found no fertility depression after semen injections but did detect high anti-sperm antibody titers. Wentworth and Mellen (1964) have shown that anti-sperm anti-bodies develop in chicken hens following intravaginal, intra-uterine and intraperitoneal artificial insemination (A.I.) and that antibody titer is negatively correlated with duration of fertility.The observation, made many times, that fertility in turkey hens declines during a breeding season of approximately 20–25 weeks led to the studies to be described. The decline in fertility is generally gradual but is sometimes dramatic and rapid with a flock showing a fertility drop of 10% or more per…