Fat distribution patterns in young amenorrheic females

The present study analyzes body fat distribution, a well-known and important indicator of reproductive capability, in young women between 18 and 28 years of age (mean=23.3 years) suffering from secondary amenorrhea and therefore temporary infertility resulting from self-starvation. Body composition parameters estimated by means of dual energy x-ray absorptiometry and the fat distribution index, indicating body shape, were compared with those of healthy controls. Although members of the infertile, amenorrheic group exhibited dramatically low body weight and total amount of body fat, and therefore a marked negative energy balance in comparison with the healthy controls, the sex-specific fat distribution patterns did not differ between infertile and fertile young women. In contrast, the lower the weight and total fat amount, the more gynoid the fat distribution, even in infertile women. This observation may be interpreted in an evolutionary sense: Our ancestors had to cope with frequent food shortages, even starvation, and therefore lengthy periods of negative energy balance. In addition to pregnancy and lactation, temporary infertility as a result of long-term negative energy balance was not an uncommon phenomenon in female life histories. Nevertheless, after a time of plenty, reproductive function recovered, and therefore the gynoid fat distribution patterns in temporarily infertile young women may be interpreted as signal of reproductive capability, which resumes after a time of surplus.     

Why do women stop reproducing before menopause? A life-history approach to age at last birth

Evolutionary biologists have long considered menopause to be a fundamental puzzle in understanding human fertility behaviour, as post-menopausal women are no longer physiologically capable of direct reproduction. Menopause typically occurs between 45 and 55 years of age, but across cultures and history, women often stop reproducing many years before menopause. Unlike age at first reproduction or even birth spacing, a woman nearing the end of her reproductive cycle is able to reflect upon the offspring she already has—their numbers and phenotypic qualities, including sexes. This paper reviews demographic data on age at last birth both across and within societies, and also presents a case study of age at last birth in rural Bangladeshi women. In this Bangladeshi sample, age at last birth preceded age at menopause by an average of 11 years, with marked variation around that mean, even during a period of high fertility. Moreover, age at last birth was not strongly related to age at menopause. Our literature review and case study provide evidence that stopping behaviour needs to be more closely examined as an important part of human reproductive strategies and life-history theory. Menopause may be a final marker of permanent reproductive cessation, but it is only one piece of the evolutionary puzzle.     

Aetiological approach of female reproductive physiology in lactational amenorrhoea.

The duration of postpartum amenorrhea and return of ovulation varies on an individual and population basis. In 1980, in Senegal, the relationship of chronic malnutrition and female fertility was investigated for 2 years. The stability of the female body regarding weight and arm circumference despite a heavy annual workload was a surprising finding. The mean female body mass index was higher for lactating women in amenorrhea than required for restoring menstruation in European women. The mean duration of postpartum amenorrhea was 18.2 +or- .6 months. The difference between those who resumed menstruation (20.9 +or- .9 months) and who still had amenorrhea (25.4 +or- 2.2 months) was significant. The duration of breast feeding determined the duration of amenorrhea. Studies have found a link between ovarian dysfunction and women in harsh third world environments and sportswomen under intensive training with both showing irregular menstruation and amenorrhea. Long duration of cycles in New Guinean women, high amount of anovulation in Zairian forest women, and suppression of testosterone and estradiol levels in hunter-gatherers were found. In affluent Europeans and urbanized women in developing countries postpartum amenorrhea dropped drastically. Long distance runners are often vegetarians with low calorie consumption and with a high degree of menstrual trouble owing to low body fat and weight-for-height. The role of beta-endorphins in the hypothalamic blockade of the gonadotropin releasing hormone pulse generator and high stress or physical training is proven. The functioning of the hypothalamo-pituitary-ovarian axis can be hurt by intensive training. Short-term fasting also suppressed the pulsatile luteinizing hormone and testosterone secretion. The protocol and methodology of an etiological study is outlined regarding the factors of this hypothesis on amenorrhea.     

Demographic and endocrinological aspects of low natural fertility in Highland New Guinea

The Gainj of highland Papua New Guinea do not use contraception but have a total fertility rate of only 4.3 live births/woman, 1 of the lowest ever recorded in a natural fertility setting. Reproductive and marital histories were obtained from 305 females and 206 males aged 10+. Each subject was asked about: number of live born offspring ever produced; number of stillbirths ever produced; number and names of offspring currently being nursed; number of current and past spouses; and the cause of dissolution of all past marriages. Blood samples were drawn from 172 volunteer female subjects aged 10-60 years and ovarian function was classified by concentration of progesterone. From an analysis of these cross-sectional demographic and endocrinological data, the causes of low reproductive output have been identified in women of this population as: late menarche and marriage, a long interval between marriage and 1st birth, a high probability of widowhood at later reproductive ages, low effective fecundability and prolonged lactational amenorrhea. These are combined with near-universal marriage, and a low prevalence of primary sterility similar to that found in other populations. Of all the factors limiting fertility, by far the most important are those involved in birth spacing, especially lactational amenorrhea. The effects of widowhood on Gainj fertility are negligible. Factors acting to lower fertility fall into 2 categories: those that determine the age of onset of reproduction and those that act to space births. Given the observed pattern of birth spacing, however, the delay in commencement of reproduction represents on average no more than 1 or 2 live births averted/woman. In contrast, were age at 1st reproduction held constant while reducing birth intervals to a mean of 2.0-2.5 years, total fertility would increase to about 7 or 8. Future research on natural fertility should focus on specific behavioral and physiological mechanisms governing the reproductive process.     

Lifestyle and fertility: the influence of stress and quality of life on male fertility

Background

Male infertility is a widespread condition among couples. In about 50% of cases, couple infertility is attributable to the male partner, mainly due to a failure in spermatogenesis. In recent times, the crucial role that modifiable lifestyle factors play in the development of infertility have generated a growing interest in this field of study, i.e. aging, psychological stress, nutrition, physical activity, caffeine, high scrotal temperature, hot water, mobile telephone use. Several studies have investigated associations between semen quality and the presence of lifestyle stressors i.e. occupational, life events (war, earthquake, etc.) or couple infertility; overall, these studies provide evidence that semen quality is impaired by psychological stress. In this review, we will discuss the impact of quality of life (modifiable lifestyle factors) and psychological stress on male fertility. In addition, the role that increased scrotal temperature along with inappropriate nutritional and physical exercise attitudes exert on male fertility will be presented.

Conclusion

The decline of male fertility, particularly associated with advancing age, incorrect lifestyles and environmental factors plays an important role on natality, and its consequences on the future on human population makes this an important public health issue in this century. Thus, modification of lifestyle through a structured program of educational, environmental, nutritional/physical exercise and psychological support, combined with the use of nutraceutical antioxidants can prevent infertility and therefore, may help couples to obtain better quality of life and improved possibility to conceive spontaneously or optimize their chances of conception.

     

Psychosocial and sociocultural aspects of infertility--a comparison between Austrian women and immigrant women

The polycystic ovarian syndrome (PCOS) is the most common endocrine disorder affecting female fertility. In this study we examined psychosocial parameters caused by infertility in PCOS women with different socio-cultural background. Symptomatology of PCOS, body composition characteristics as well as psychosocial parameters were examined in 49 PCOS infertility patients of the University Clinic for Gynecology and Obstetrics in Vienna, who originated from two different socio-cultural subgroups--Austrian women and Moslem immigrant women. In the appearance of the symptoms the typical heterogeneity of PCOS could be found in both subgroups with no differences. However, differences in the psychosocial aspects were impressive. Women from Islamic background do have a very high reproductive pressure. The Moslem immigrant PCOS women suffer more from infertility than Austrian women do.     

The effects of type of female circumcision on infertility and fertility in Sudan

This study explores the association between type of female circumcision and infertility and fertility in Sudan using the 1989-90 Demographic and Health Survey. It is hypothesized that women with either Pharaonic or Intermediate circumcision would have higher infertility and lower fertility compared with women with Sunna circumcision, and that uncircumcised women would have the lowest infertility and highest fertility of the three groups. This hypothesis, a widely held assumption, proved to be largely incorrect. Though women with Pharaonic or Intermediate circumcision did have a higher prevalence of primary infertility than uncircumcised women, women with Sunna circumcision had even lower rates of primary infertility compared with uncircumcised women. This pattern prevailed in multivariate models controlling for confounding variables, where women with Pharaonic or Intermediate circumcision had significantly higher primary infertility. Moreover, though women with Pharaonic or Intermediate circumcision also had the highest prevalence of secondary infertility, once confounding covariates were controlled in multivariate models, there was no significant difference among the three groups of women. With respect to fertility, the total fertility rate was 7.6 for women with Pharaonic or Intermediate circumcision, 8.1 for women with Sunna circumcision and 8.3 for uncircumcised women. Differences in fertility were found to be insignificant when covariates were controlled. The multivariate models were estimated using logistic regression. In conclusion, Pharaonic or Intermediate circumcision may be associated with higher primary infertility while there was no evidence suggesting that either secondary infertility or fertility was associated with a woman's circumcision status.     

Role of oxidative stress in female reproduction

In a healthy body, ROS (reactive oxygen species) and antioxidants remain in balance. When the balance is disrupted towards an overabundance of ROS, oxidative stress (OS) occurs. OS influences the entire reproductive lifespan of a woman and even thereafter (i.e. menopause). OS results from an imbalance between prooxidants (free radical species) and the body's scavenging ability (antioxidants). ROS are a double-edged sword – they serve as key signal molecules in physiological processes but also have a role in pathological processes involving the female reproductive tract. ROS affect multiple physiological processes from oocyte maturation to fertilization, embryo development and pregnancy. It has been suggested that OS modulates the age-related decline in fertility. It plays a role during pregnancy and normal parturition and in initiation of preterm labor. Most ovarian cancers appear in the surface epithelium, and repetitive ovulation has been thought to be a causative factor. Ovulation-induced oxidative base damage and damage to DNA of the ovarian epithelium can be prevented by antioxidants. There is growing literature on the effects of OS in female reproduction with involvement in the pathophsiology of preeclampsia, hydatidiform mole, free radical-induced birth defects and other situations such as abortions. Numerous studies have shown that OS plays a role in the pathoysiology of infertility and assisted fertility. There is some evidence of its role in endometriosis, tubal and peritoneal factor infertility and unexplained infertility. This article reviews the role OS plays in normal cycling ovaries, follicular development and cyclical endometrial changes. It also discusses OS-related female infertility and how it influences the outcomes of assisted reproductive techniques. The review comprehensively explores the literature for evidence of the role of oxidative stress in conditions such as abortions, preeclampsia, hydatidiform mole, fetal embryopathies, preterm labour and preeclampsia and gestational diabetes. The review also addresses the growing literature on the role of nitric oxide species in female reproduction. The involvement of nitric oxide species in regulation of endometrial and ovarian function, etiopathogenesis of endometriosis, and maintenance of uterine quiescence, initiation of labour and ripening of cervix at parturition is discussed. Complex interplay between cytokines and oxidative stress in the etiology of female reproductive disorders is discussed. Oxidant status of the cell modulates angiogenesis, which is critical for follicular growth, corpus luteum formation endometrial differentiation and embryonic growth is also highlighted in the review. Strategies to overcome oxidative stress and enhance fertility, both natural and assisted are delineated. Early interventions being investigated for prevention of preeclampsia are enumerated. Trials investigating combination intervention strategy of vitamin E and vitamin C supplementation in preventing preeclampsia are highlighted. Antioxidants are powerful and there are few trials investigating antioxidant supplementation in female reproduction. However, before clinicians recommend antioxidants, randomized controlled trials with sufficient power are necessary to prove the efficacy of antioxidant supplementation in disorders of female reproduction. Serial measurement of oxidative stress biomarkers in longitudinal studies may help delineate the etiology of some of the diosorders in female reproduction such as preeclampsia.     

Reproduction: the Canadian family in transition

3 trends suggest that the reproductive function of the Canadian family is in transition. 1st, fertility has fallen and remains below the replacement level. In 1985, the total fertility rate was 1.67, the lowest in 60 years. Since 1971, it has not risen above 2.1 births/woman, the replacement level. 2nd, an increasing proportion of women are spending a larger part of their lives without having any children. In the 1981 census, 22% of ever-married women between 15 and 44 years had not yet borne children, compared with only 14% recorded in the 1961 census. While the proportion of women who are childless at the end of their reproductive years has risen only slightly, a larger number of women are postponing having children even as the risk of becoming sterile in the interim becomes greater. The combined effect of postponing both marriage and childbearing will most probably be to increase the proportion of women remaining without children. The 3rd trend is the increasing proportion of women who are having children without getting married. Among the consequences of premarital pregnancy are the stress on single mothers, the need for social assistance, the cost of maintenance programs, and the need for more child care. These changes in attitude toward marriage and family formation could have major implications for individuals and society. A fertility rate below replacement level could be stressful for society, resulting in population decline, and changes in age structure that could negatively affect the economy.     

The force of selection on the human life cycle

In this article, I present evidence for a robust and quite general force of selection on the human life cycle. The force of selection acts in remarkably invariant ways on human life histories, despite a great abundance of demographic diversity. Human life histories are highly structured, with mortality and fertility changing substantially through the life cycle. This structure necessitates the use of structured population models to understand human life history evolution. Using such structured models, I find that the vital rates to which fitness is most sensitive are prereproductive survival probabilities, particularly the survival of children ages 0 to 4 years. The fact that the preponderance of selection falls on transitions related to recruitment combined with the late age at first reproduction characteristic of the human life cycle creates a fitness bottleneck out of recruitment. Because of this, antagonistic pleiotropy with any trait that detracts from the constituent transitions to recruitment is expected. I explore the predictors of variation in the force of selection on early survival. High fertility increases the selective premium placed on early survivorship, whereas high life expectancy at birth decreases it.     

Reproductive plasticity in Polistes paper wasp workers and the evolutionary origins of sociality

Regulatory pathways in solitary species provide the raw materials for the evolution of sociality. Therefore, comparing the mechanisms that mediate reproductive plasticity in social species and their solitary ancestors can provide insight into the evolutionary origin of sociality. In many solitary insects, the effect of juvenile hormone (JH) on fertility is mediated through the fat body; individuals in good physical condition show a stronger fertility response to JH than individuals in poor physical condition. Here, we test whether a similar, condition-dependent JH response mediates fertility in workers of the primitively eusocial Polistes dominulus wasps. We test how body weight, JH, and adult nutrition influence worker ovarian development. Both JH-treatment and adult nutrition dramatically increased ovarian development. Body weight also influenced ovarian development, as large workers developed more eggs than smaller workers. Body weight and fat are strongly linked in P. dominulus workers, so these results suggest that the fat-dependent JH responsiveness common in solitary insects is conserved in social wasps. The simple, ancestral relationship between reproductive investment and physical condition may facilitate cooperation by allowing workers to adaptively allocate energy into reproduction based on their probability of successfully becoming a queen.     

Age differences between distributions of genotypes among pregnant women: evidence of fertility selection

The number of children produced by a modern woman is usually below her total reproductive capacity and is determined by circumstances other than natural selection. It is, therefore, practically impossible to detect differences in natural fertilities associated with different types (e.g. phenotypes, genotypes) of women. This does not mean, however, that natural selection at the reproductive level cannot at all be detected today. If women of a particular type have high natural fertility, this usually means that they reproduce (become pregnant) at a higher rate than women of a type with lower natural fertility. Hence, when there is a limit on the number of children, women of the first type will reach the limit at an earlier age than women of the second type. As a result, types that have a higher natural fertility should be overrepresented among pregnant women of younger ages and, consequently, underrepresented among older ones, as compared to types with a lower natural fertility. Based on this notion, a model of age-related differences between distributions of types among pregnant women is suggested. The model is applied to data on MNSs-blood group and PGM1 (phosphoglucomutase) types in a sample of pregnant women and an evidence of natural selection at the reproduction level associated with these genetic markers is obtained.     

Nutrition, infant feeding and post-partum amenorrhoea in rural Bangladesh

The extent to which differences in the duration of postpartum amenorrhea among chronically malnourished women in rural Bangladesh are related to seasonal patterns of food supply, maternal nutrition, education, and patterns of infant feeding was investigated by application of multivariate hazards models with time-varying covariates. The data were derived from the Birth Interval Dynamics study in Matlab and covered close to 1800 births. Parity, education, season of birth, maternal weight, and infant supplementation all were found to affect the duration of postpartum amenorrhea among these women. Education of 5 or more years had a positive effect on the resumption of menses. Higher parity women, who were older, had longer periods of amenorrhea, as did women who gave birth in October-December. As a measure of nutritional status, the woman's weight at pregnancy termination showed a highly significant positive coefficient, indicating that improved maternal nutrition increased the likelihood of resuming menstruation. Food supplementation, which tends to decrease breastfeeding, also significantly increased the risk of resuming menstruation and had an effect independent of the other variables. When the data were analyzed by season, the most striking finding was the strong influence of education on children born during October-December (who are too young to be directly affected by the larger food supply at birth during the harvest season). The other seasons showed weaker effects of education and a stronger effect of supplementation, perhaps because these infants are older during the harvest season and thus can benefit from supplements.     

Evolution of delayed reproduction in uncertain environments: a life-history perspective

Environmental uncertainty alone can select for delayed reproduction; however, its relative role in the evolution of delayed reproduction across life histories is not known. Along a life-history spectrum from low-survival/high-fertility species to high-survival/low-fertility species, we show that the latter are more likely to evolve delayed reproduction if fertility varies over time. By contrast, if survival varies over time, low-survival life histories are more likely to evolve delays. If there is variation in both survival and fertility, and if this variation is positively associated, the evolutionarily stable reproductive delay is decreased (relative to independent variation in survival and fertility). Conversely, if variation in survival and fertility is negatively associated, the evolutionarily stable reproductive delay is increased. We further show that environmental uncertainty can drive the evolution of delayed reproduction in an iteroparous organism but only in the special case where juvenile survival is greater than adult survival. For common iteroparous life histories (adult survival > juvenile survival), environmental uncertainty does not select for delayed reproduction. Thus, any benefits that delayed reproduction might have on reproduction or survival could be especially important in explaining the common observation of delayed reproduction in many vertebrates and perennial plants.     

Human fertility and land tenure in highland Bolivia

Basic demographic data of landless and landed peasants from the highlands and valley of Northern Potosi, Bolivia, are compared. Household size and crude birth rates are larger in the highlands than in the valley. Within the highland population, no statistically significant difference was observed between the age-specific fertility of landless and landed women, nor in the survivorship ratio of their offspring. The prevalence of exchange and reciprocity at the village level may be responsible for the absence of important differences in the fertility and mortality patterns of the landed and the landless. Information was obtained from a total of 333 households, which included a population of about 1700 people or 20% of the Jukumani ayllu (ethnic group). No relationship between altitude and human reproduction was noted among Jukumanis. Highland Jukumani women begin reproducing in their late teens; by their mid-20s only about 30% of the 21-25 year old female cohort remains childless. 2 major tax categories of people emerge in the area under consideration: taseros, the landed peasantry who are obligated to pay taxes, and kantu runas, the landless laborers who do not pay taxes. Tasero women are most fertile from their mid-20s until their mid-30s whild kantu runa women are more fertile later in life. Within the highland territory there are no statistically significant differences in the infant and child mortality patterns of taseros and kantu runas. The higher household size and crude birth rates of highlanders suggests that hypoxic stress may not depress fertility. Taseros and kantu runas differ in fertility patterns in degree rather than in kind. It is concluded that although differential access to natural resources may translate into slightly higher crude birth rates and child/woman ratios, it does not have much bearing on the fertility of women, or the mortality or household size of taxpayers and kantu runas. A possible explanation for the Jukumani anomaly may be the prevalence of reciprocity and exchange between taseros and kantu runas, especially relating to land access and physical care.     

阴道微生物与多囊卵巢综合征相关性的研究进展

多囊卵巢综合征（PCOS）是育龄期女性最常见的内分泌失调性疾病,具有高度的异质性和复杂性,是女性不孕的常见因素之一,且PCOS会显著增加2型糖尿病、肥胖、心血管疾病、高血压和心理疾病的风险,严重危害患者健康。阴道微生物群是每个女性特有的,正常的阴道微生物群在维持女性生殖健康方面起着至关重要的作用,而异常的阴道微生物定植与不良生殖结局密切相关。结合PCOS患者不孕症、高流产率、高早产率和胚胎停育等不良妊娠事件的发生,阴道乃至整个生殖道的不良微生物群可能通过免疫和炎症反应等途径影响着PCOS的发生发展,但其机制仍不清楚。因此,本文综述了阴道微生物群和PCOS患者相关性的研究概况,包括PCOS患者阴道微生物群的组成、阴道微生物群与PCOS的发生机制以及PCOS患者阴道微生物对生殖结局的影响,以期为PCOS的诊疗提供新思路。

     

Flux induced biochemical differentiation.

Any realistic model of human fertility should encompass the distributions and interactions of three time intervals a fecund married woman may experience repeatedly in her childbearing period: (1) waiting time for a conception, (2) gestation period, and (3) period of postpartum amenorrhea. Perrin &; Sheps (1964) presented a model in which human reproduction is viewed as a Markov renewal process with a finite number of states. Das Gupta (1973b) presented a general probability model of fertility along the lines suggested by Perrin &; Sheps which removes two limitations of their model. First, it does not assume that the distributions of durations of stay in the fertility states are independent of each other. Second, it allows us to study the effect of breast-feeding on demographic characteristics, such as interval between live births or birth rate. Results derived in Das Gupta (1973b) include the distributions of time intervals and the exact probabilities of different states at a particular time. The present paper includes additional results pertaining to the same general model, such as the distribution of number of conceptions in a fixed period of time, the distribution of time needed for a fixed number of conceptions, pregnancy rate and fertility rate, and the distribution of the time elapsed since last live birth. The general results are applied to specific models to obtain some known results.     

Induced abortion ratio in modern Sweden falls with age,but rises again before menopause

A woman's reproductive value decreases over her reproductive life span and it is therefore predicted that the likelihood of termination of investment in a child decreases with increasing age. An eventual increase in termination ratio in the oldest age groups, as is often found in abortion statistics, could depend on older women on average having larger families rather than on age per se. We used data on abortions and births in Sweden during 1994 to investigate how abortion ratio is related to age and parity of women. We found that age-specific abortion ratio is U-shaped (i.e. that it is highest for the youngest and for the oldest age groups) in each parity class from zero to four children but that age-dependence breaks down in higher parity classes (5, ≥6). Thus, for each of the parity classes 0–4, the incidence of abortion decreases with age up to a point, but increases again as women approach menopause. This late increase in induced abortion ratio seems to depend on age per se. The data indicate that abortion ratio is an inverse function of fertility, and that investment in new reproduction gradually decreases as a woman approaches menopause. Assuming grandmothering as an important driving force in human life history evolution, such a pattern might indicate that the transition from behavioural investment in one's own children to one's grandchildren is a gradual process similar to the decline in ovarian function.     

Phosphoglucomutase genetic polymorphism and human fertility.

We studied the phosphoglucomutase phenotype in relation to fertility parameters in a consecutive series of 204 women who had delivered a normal live-born child in Rome. A highly significant association was found between age of the women and phosphoglucomutase phenotype, suggesting a reduced rate of reproduction among women of phosphoglucomutase Type 1. Previous spontaneous abortion appears related to both age and phosphoglucomutase enzymatic type. An increased incidence of abortion in women of older ages was observed only in phosphoglucomutase Type 1. Gestational duration and fetal intrauterine growth rate are also significantly associated with maternal phosphoglucomutase phenotype. The pattern is complex, but also in this instance the influence of maternal age was evident. Considered altogether, the data suggest that phosphoglucomutase may have an important role in zygote development and survival through the whole span of intrauterine life.     

Fitness Characteristics and Allozyme Heterozygosity in an Artificial Population of the Sable Martes zibellina L.

Associations between some characteristics of fitness (the age of the first reproduction, life span, fertility, and the number of missed pregnancies) and heterozygosity for some allozyme loci have been studied in a population of the sable Martes zibellina L. kept in cages at a farm. Of all fitness characteristic studied, a weak correlation has only been found between heterozygosity and the age of the first reproduction (maturation rate). The age of the first reproduction is positively associated with the life span and fertility. The results obtained are discussed in terms of the relationship between the genetic variation of longevity and developmental rate and prospects of their application to breeding practice.