SEARCH · PubMed Health

Results for “Fertility Decline”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2026

Research progress on multi-mechanism analysis and protection strategies of ovarian aging and fertility decline.

Age-related fertility decline is an increasingly important challenge in reproductive medicine, driven largely by progressive ovarian aging. The aging ovary undergoes functional deterioration characterized by reduced ovarian reserve and declining oocyte quality, ultimately limiting female reproductive lifespan. Although multiple molecular and cellular processes associated with ovarian aging have been identified, these mechanisms are often discussed independently, limiting an integrated understanding of how they interact within the ovary. In this review, we propose an ovary-centered, multi-mechanistic framework to organize current evidence on ovarian aging and fertility decline. We discuss how genomic instability, telomere attrition, mitochondrial dysfunction, oxidative stress, chronic cellular stress responses, and alterations in ovarian signaling and microenvironmental homeostasis collectively contribute to follicle depletion and impaired oocyte competence. Particular emphasis is placed on signaling pathways involved in follicle activation and stress adaptation, including PI3K/AKT/mTOR, FOXO3, Hippo, and AMPK-Sirtuin networks, while acknowledging that many mechanistic relationships remain incompletely defined in physiological ovarian aging. Building on this integrative perspective, we further evaluate mechanism-oriented intervention strategies, including mitigation of cellular stress, metabolic and signaling modulation, optimization of the ovarian microenvironment, established fertility preservation technologies, and emerging exploratory approaches. By integrating current mechanistic and translational evidence, this review provides a conceptual framework for understanding ovarian aging and highlights future directions for evidence-based fertility preservation and reproductive health management in the context of aging.

Humans↗

PubMed1992

[Analysis of the fertility decline in Japan--focusing on the period of 1950-60 and 1975-85].

Marked fertility declines have been observed in Japan from 1950-60 and 1975-85. The dynamic structure of the fertility decline in the two periods was analyzed employing the Standardization Approach and Bongaarts Model of Proximate Determinants Analysis. The results indicate that the fertility decline in 1950-60 was mainly caused by a drop in marital fertility due to the expanding diffusion of contraception practices and increases in induced abortion. Increased age at marriage cannot be discounted as a factor also. The fertility decline in 1975-85 was mostly caused by delay of marriage as well as a reduction in proportion of the reproductive population which is composed of a cohort born in 1960 or later.

Adolescent↗

PubMed1992

West Indian gender relations, family planning programs and fertility decline.

Nearly all West Indian islands initiated marked fertility declines sometime between 1960 and 1970. Family planning programs have not played an important role in these declines. Neither have other variables that conventional social theory tells us should promote reduced family sizes, like education and rising standards of living. The historical experience of Barbados and Antigua, which reached replacement-level fertility in the 1980s, suggests that West Indian fertility declines reflect structural changes in national economies that created job opportunities for women. Family planning programs need to be evaluated with reference to the distinctive health and human rights goals other than fertility transition that they can effectively reach.

Adult↗

PubMed1991

Fertility decline in Taiwan: a study using parity progression ratios.

Taiwan's decline in fertility is studied by using period parity progression ratios. Levels of marriage and motherhood are found to have been high and essentially constant though the late 1980s, suggesting that the decline has been due almost entirely to declines in second and higher order-births. Families with three or more children play an important role in maintaining the current level of fertility. The level of fertility would be even lower without these families. They contributed more than one-half child per woman to the total fertility rate during most of the 1980s. Total fertility rates computed from the period parity progression ratios indicate a substantially higher level of fertility than the conventional total fertility rate; they remained above or at replacement level through 1988. A formal demographic analysis suggests that the conventional total fertility rate has been depressed by shifts in age at childbearing.

Adult↗

PubMed1975

Emigration and fertility decline: the case of Barbados.

This paper examines the role of emigration in the recent fertility declines which have occurred on the island of Barbados. Barbados with a history of over two centuries of out-migration has experienced in the period 1951-1970 very significant migration loss. In the period 1960-1970 and up to the present fertility has been declining. An important question is what part has this net migration loss of 32,600 had on the reduction of the crude birth rate from 33.6 in 1960 or from 31.5 in 1956 to 20.5 in 1970? Using officially published net migration loss figures and supplementing them with data on Barbadians living overseas, we calculated the crude birth rates which would have occurred had there been no migration loss. We also calculated the numbers of births to be expected if certain age-specific fertility rates were maintained and compared these with the births to residents plus the calculated births to Barbadians overseas. We conclude that in both cases emigration is a very significant contributor to the fertility declines which have occurred and are still underway.

Adolescent↗

PubMedDate not supplied

The U.S. fertility decline, 1961-1975: the contribution of changes in marital status and marital fertility.

Changes in marital fertility have accounted for 83 percent of the decline in total fertility since 1971; changes in marital status accounted for 19 percent, and changes in nonmarital fertility had only a negligible effect. Declines in the level of marital fertility account for a substantial part of the overall decrease; postponement of childbearing did not occur in any significant degree until the 1970s.

Adolescent↗

PubMed1977

Fertility decline in Barbados: some spatial considerations.

Despite its small size, Barbados exhibits some striking regional differences in fertility levels, which persisted during a period of major fertility decline in the 1960s. Regression analyses are performed for 28 subregions, using sex ratio, male occupational structure, female education, and female employment for 1960 and 1970 as the independent variables. The spatial influence of the Barbados family planning program is also considered. The author argues that a concentration of family planning programs in areas of greatest accessibility and modernization contributes to spatial variations in fertility.

Adolescent↗

PubMed1991

Sex and respectability in an age of fertility decline: a Sicilian case study.

The paper examines two aspects of coitus interruptus as a sexual practice: (1) how, in the age of fertility decline in Western Europe, its meaning was reinterpreted from an earlier theological view that condemned it as licentious to a nineteenth century view that emphasized restraint, and (2) how it was actually experienced by a socially stratified birth-controlling population in rural Sicily, ca 1900-1970. The sequential experiences of gentry, artisans, and peasants in the Sicilian case study of transition from high to low fertility are consistent with late twentieth-century interpretations of coitus interruptus by Foucault and others as sexually restraining yet empowering. In each group, adoption of the practice enhanced access to respectability in a context of cultural and economic change. Moreover, those who adopted the practice increasingly stigmatized married couples with high birth parities as overly dominated by their sexual instincts and unworthy of respect.

Coitus Interruptus↗

PubMed1976

Influence of instantaneous fertility decline to replacement level on population growth: an alternative model.

If age-specific birth rate mx of a stable population drop abruptly to mx/Ro, where Ro is the net reproduction rate, then, according to Keyfitz, the size of the ultimate stationary population relative to that at the beginning of the process is given by I = beoo(Ro - 1)/(rmuRo), where b and r are the birth rate and the rate of growth, respectively, of the stable population, eoo the life expectancy at birth, and mu the average age at childbirth in resulting stationary population. Noting that the decline in mx need not necessarily be uniform, investigation has veen carried out to examine the effect on I when fertility decline is more rapid at higher ages. In particular, the effect of the reduced age-specific rates such as mxe-rx (which also produces a stationary population) has been analyzed, and simplifications of the results carried out separately for three different models of the net maternity function. It has also been shown the when mx drops abruptly to some m* x, where the form of m*x need not be specified except for the restriction that the resulting population will be stationary, the value of the index can be approximately obtained from I* = beoo (1 - rmu/2), where mu is the average age at childbearing of theinitial stable population.

Birth Rate↗

PubMed1978

The role of family planning in recent rapid fertility declines in developing countries.

World Fertility Survey data for ten developing countries are used to examine the respective roles of development and family planning in influencing the regulation of fertility. The findings show that high proportions of women at all socioeconomic levels in the countries studied wanted no more children, including large proportions among rural, poor, and uneducated women with few children. The data also show that despite the limitations of underdevelopment, in countries with strong family planning programs knowledge and use of contraception was high. These findings confirm that there is a large unmet demand for family planning and point to the importance of continued allocation of funds to support service programs.

Adolescent↗

PubMedDate not supplied

Determinants of fertility decline in China, 1981: analysis of intermediate variables.

This study examines the proximate determinants of fertility in China by making use of the data collected by the One-per-Thousand Sample Fertility Survey of 1982. The results indicate that the most important inhibitor of potential fertility is deliberate control. Its contribution to fertility change has been far greater than all other proximate determinants. The marital structure of the population is also an important factor, while lactational infecundability and induced abortion are relatively unimportant. Comparative results by using data from the In-depth Fertility Survey conducted in Shanghai Municipality, Hebei and Shaanxi Provinces in April 1985 agree well in the ranking of the four intermediate factors. The findings point to successful family planning program and government population policies, which propelled the fertility transition to a substantial degree. Further research needs and policy implications of the results of the study are discussed.

Adolescent↗

PubMed1977

A component analysis of recent fertility decline in singapore.

To aid in achieving demographic goals, since 1968 the government of Singapore has passed a series of laws designed to limit family size. Policies were instituted in 1968 to discourage couples from having more than three children; policies introduced in 1973 discouraged having more than two. Trends in fertility rates and in the numbers of abortions and sterilizations in recent years are consistent with the intent of these social policies. Decline in third and subsequent births was the most important factor in fertility decline after 1972, and the numbers of abortions and sterilizations undergone by higher parity women have increased substantially sin"e 1970. Although other factors have affected fertility in Singapore, the data suggest that the disincentives have played a role in continued fertility decline in recent years.

Abortion, Legal↗

PubMed1978

Two determinants of fertility decline: a test of competing models.

This paper compares alternative models for the process by which education and infant mortality changes may combine to reduce fertility. A linear, interactive model appears most suitable. Substantively, it indicates that those countries with a combination of low infant mortality rates and high educational enrollments experience synergistically large declines in fertility. Patterns of contraceptive use are also consistent with this model.

Adolescent↗

PubMed1978

Patterns of fertility decline in developing countries, 1950-75.

Since 1965 there have been substantial declines in the crude birth rates of many countries in the developing world, particularly the largest countries. This auspicious trend is shown clearly in an analysis of population figures for the last 25 years, despite the fact that there are deficiencies in the data. In 1950 the average crude birth rate for developing countries was 42 per thousand per year. Over the next 15 years, declines in the crude birth rate were limited to a relatively few, and for the most part small, countries. After 1965, however, for the 13 developing countries with a population numbering 35 million and over, there have been declines in the crude birth rate averaging 13 percent, with declines of over 12 percent in 9 of them. The effects of a number of sociodemographic factors on crude birth rates are examined, and the analysis shows that increases in the age at marriage and decreases in marital fertility were the principal factors affecting declines since 1965.

Adolescent↗

PubMedDate not supplied