Topic
Fertility
About: Fertility is a research topic. Over the lifetime, 29988 publications have been published within this topic receiving 681106 citations.
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TL;DR: Treatment for cancer during adolescence carries a substantial risk for early menopause among women still menstruating at age 21, and increasing use of radiation and chemotherapy suggests that these women should be made aware of their smaller window of fertility so that they can plan their families accordingly.
400 citations
TL;DR: It is suggested that, on a large scale, age at menarche is mainly determined by extrinsic factors such as living conditions, whileAge at menopause seems to be mainly influenced by intrinsic factorssuch as the reproductive history of individuals.
Abstract: 1 Abstract The purpose of this study was to review published studies on the variability of age at menarche and age at menopause throughout the world, and to identify the main causes for age variation in the timing of these events. We first present a summary table including mean (or median) values of the age at menarche in 67 countries, and of the age at menopause in 26 countries. General linear models showed that mean age at menarche was strongly linked to the mean female life expectancy, suggesting that one or several variables responsible for inequalities in longevity similarly influ- enced the onset of menarche. A closer examination of the data revealed that among several variables reflecting living conditions, the factors best explain- ing the variation in age at menarche were adult illiteracy rate and vegetable calorie consumption. Because adult illiteracy rate has some correlation with the age at which children are involved in physical activities that can be detri- mental in terms of energy expenditure, our results suggest that age at menar- che reflects more a trend in energy balance than merely nutritional status. In addition, we found the main determinant of age at menopause to be the mean fertility. This study thus suggests that, on a large scale, age at menarche is mainly determined by extrinsic factors such as living conditions, while age at menopause seems to be mainly influenced by intrinsic factors such as the re- productive history of individuals. Finally, these findings suggest that human patterns cannot be addressed solely by traditional, small-scale investigations on single populations. Rather, complementary research on a larger scale, such as this study, may be more appropriate in defining some interesting ap- plications to the practical problems of human ecology.
399 citations
TL;DR: It is demonstrated that a small number of intermediate fertility variables are responsible for most of the variation in fertility levels of populations and four variables--proportion married, contraception, induced abortion, and postpartum infecundability--are generally the most important determinants of fertility.
Abstract: Based on the application of an aggregate reproductive model, this study demonstrates that a small number of intermediate fertility variables are responsible for most of the variation in fertility levels of populations. Four variables--proportion married, contraception, induced abortion, and postpartum infecundability--are generally the most important determinants of fertility; the other intermediate factors are of less interest except in unusual circumstances. These four factors explain 96 percent of the variance in the total fertility rate in a sample of 41 populations that include developing and developed countries as well as historical populations. In the last section, the average fertility effect of the principal intermediate fertility variables is estimated for groups of contemporary populations with different total fertility rates.
398 citations
TL;DR: In this article, a general theory of fertility and parental investment across a broad spectrum of human societies is presented, based on life history theory and evolutionary biological models of optimal fertility regulation.
Abstract: This paper has two interrelated goals. The first is to offer a general theory of fertility and parental investment across a broad spectrum of human societies. The second is to provide a perspective that unifies traditionally separate domains of anthropology. The basic foundation for the analysis is life history theory and evolutionary biological models of optimal fertility regulation. This tradition is combined with human capital theory in economics to produce a more general theory of investments in embodied capital within and between generations. This synthesis results in a series of optimality models to examine the decision processes underlying fertility and parental investment upon which natural selection is expected to act. Those models are then applied to the hunting and gathering lifeway. This analysis focuses both on problems that all hunting and gathering peoples face and on the production of variable responses in relation to variable ecologies. Next, this consideration of optimal parental investment and fertility behavior in hunter-gatherers is united with existing models of the proximate determinants of human fertility. The analysis of proximate mechanisms is based on the idea that natural selection acts on the final phenotypic outcome of a coordinated system of physiological, psychological and cultural processes. The important conditions affecting parental investment and fertility in modern socioeconomic contexts are then discussed. An explanation of modern fertility and parental investment behavior in terms of the interaction of those conditions with the physiological and psychological mechanisms that evolved during our hunting and gathering history is proposed. The proposal is that skills-based competitive labor markets increase the value of parental investment in children and motivate better-educated, higher income parents to invest more per child than their less-educated, lower-earning counterparts. It is also suggested that the deviation from fitness maximization associated with low modern fertility is due to excess expenditures on both parental and offspring consumption, indicating that our evolved psychology is responding to cues in the modern environment that are not directly related to the fitness impacts of consumption. © 1996 Wiley-Liss, Inc.
397 citations
TL;DR: Data suggest a role for specific biologic causes of infertility, but not for fertility drugs in overall risk for ovarian cancer, as suggested in case-control studies conducted between 1989 and 1999.
Abstract: Controversy surrounds the relations among infertility, fertility drug use, and the risk of ovarian cancer. The authors pooled interview data on infertility and fertility drug use from eight case-control studies conducted between 1989 and 1999 in the United States, Denmark, Canada, and Australia. Odds ratios and 95% confidence intervals were calculated, adjusting for age, race, family history of ovarian cancer, duration of oral contraception use, tubal ligation, gravidity, education, and site. Included in the analysis were 5,207 cases and 7,705 controls. Among nulligravid women, attempts for more than 5 years to become pregnant compared with attempts for less than 1 year increased the risk of ovarian cancer 2.67-fold (95% confidence interval (CI): 1.91, 3.74). Among nulliparous, subfertile women, neither any fertility drug use (odds ratio (OR) = 1.60, 95% CI: 0.90, 2.87) nor more than 12 months of use (OR = 1.54, 95% CI: 0.45, 5.27) was associated with ovarian cancer. Fertility drug use in nulligravid women was associated with borderline serous tumors (OR = 2.43, 95% CI: 1.01, 5.88) but not with any invasive histologic subtypes. Endometriosis (OR = 1.73, 95% CI: 1.10, 2.71) and unknown cause of infertility (OR = 1.19, 95% CI: 1.00, 1.40) increased cancer risk. These data suggest a role for specific biologic causes of infertility, but not for fertility drugs in overall risk for ovarian cancer.
397 citations