Reproductive life of Bhoksa women

The paper discusses the reproductive life of 111 ever-married Bhoksa women. The mean age at marriage for women of all ages among Bhoksas, like other tribal populations, is high, unlike the caste populations. The mean ages at first birth of the pooled sample and of the completed fertility cases suggest late and early marriages of the older and younger generations. The maximum number of marriages occur between 15 and 19 years and of first births between 16 and 20 years.

Percentage of reproductive wastage is high in both the lower and higher age groups. Young mothers with low birth orders and older mothers with high birth orders display a high frequency of reproductive wastage. Evidently, both birth order and the age of the mother have effects on reproductive wastage.

Average number of children ever born (including stillbirth but not abortion or miscarriage) per mother of all ages is the highest among Bhoksas of all the studied ethnic groups of India. The Bhoksa, like caste populations, show a high number of children ever born per mother of completed fertility. Quite a high masculinity in the secondary sex ratio, like other mongoloid population is noticed.

The contribution of mortality component to the Total Index of Opportunity for Selection is more than that of the fertility component. Bhoksas conform to the general low range of net reproductive index, which is however greater than unity, suggesting that they are in a growth stage.     

Fertility,migration, and mortality in an old order Amish community

Mortality, fertility, and migration data were used to identify population structure in a group of Old Order Amish living in New York State. Two thousand and sixteen individuals were accounted for since the community was first formed in 1948 and this is nearly total ascertainment of the population. Further, ethnography compared Amish households to neighboring non-Amish households to understand differences in health beliefs, caregiving patterns, and economic strategies. Despite evidence that suggests that the Amish have health risks comparable to U.S. population and that they under-utilize health care, this study demonstrates that Amish age standardized death rates are 19% below the U.S. death rate in 1960. Natural fertility combined with low infant mortality, migrating to form new communities when population density increased, and selective but appropriate use of western biomedicine have emerged as strong cultural patterns that facilitated reproductive success and longevity among the Amish. Am. J. Hum. Biol. 10:619–628, 1998. © 1998 Wiley-Liss, Inc.     

The desire for multiple pregnancy in male and female infertility patients

BACKGROUND: It is apparent that many fertility patients consider multiple birth an ideal treatment outcome. We wished to evaluate the desire for multiple birth among patients, and the effect of patient demographics and recognition of the increased fetal risks of multiple pregnancy on this desire. METHODS: This was a prospective questionnaire study completed by 801 male and female infertility patients attending a tertiary level Canadian university fertility clinic. Two logistic regression analyses were performed with desire for multiple birth with next fertility treatment and recognition of the increased fetal risks of multiple pregnancy as the dependent variables. RESULTS: 41% of patients desired a multiple birth. Increasing duration of infertility or previous assisted reproductive treatment increased, and having previous children or recognition of the increased fetal risks decreased, this desire. Patient age or sex did not affect desire for multiple birth. Previous assisted reproductive treatment was associated with increased recognition of the fetal risks of multiple pregnancy. CONCLUSIONS: A significant proportion of fertility patients considers multiple birth an ideal treatment outcome. Recognition of the increased fetal risks of multiple pregnancy significantly reduced this desire. Patient education may play an important role in assisting physicians in the quest to reduce the contribution of assisted reproductive treatment to multiple births and their attending complications.     

The demography of menopause

Menopause marks a time of dramatic hormonal and often social change for women. Both risk factors and health needs are likely to change as women pass through menopause. This paper examines the demographic characteristics of the world population of menopausal and post-menopausal women, and also examines the implications of menopause for mortality risks. The numbers of women involved are large. Using age 50 as a proxy for menopause, about 25 million women pass through menopause each year, and we estimate that in 1990 there were 467 million post-menopausal women in the world, with an average age of about 60 years. By 2030, the world population of menopausal and postmenopausal women is projected to increase to 1.2 billion, with 47 million new entrants each year. The mortality implications of menopause are also substantial. Ratios of female to male mortality risks from all causes and from all major cause groups except neoplasms decline to low levels around menopause or shortly thereafter, and then rise again to near unity. This pattern is taken as evidence that the female reproductive period is broadly protective of health, but that this protection disappears after menopause. The main protective effect is through reduced risk of cardiovascular disease mortality, partially offset by increased risks of cancer mortality, particularly of the breast and endometrium.     

Demographic consequences of unpredictability in fertility outcomes

Child survival is probabilistic, but the unpredictability in family formation and completed family size has been neglected in the fertility literature. In many societies, ending the family cycle with too few or too many surviving offspring entails serious social, economic, or fitness consequences. A model of risk‐ (or variance‐) sensitive adaptive behavior that addresses long‐term fertility outcomes is presented. The model shows that under conditions likely to be common, optimal, risk‐sensitive reproductive strategies deviate systematically from the completed family size that would be expected if reproductive outcome is were predictable. This is termed the “variance compensation hypothesis.” Variance compensation may be either positive or negative, resulting in augmented or diminished fertility. Which outcome obtained is a function of identifiable social, economic, and environmental factors. Through its effect on fertility behavior, variance compensation has a direct bearing on birth spacing and completed fertility, and thereby on problems in demography and human population biology ranging from demographic transitions to maternal depletion and child health. Risk‐sensitive models will be a necessary component of a general theory of fertility. Am. J. Hum. Biol. 14:168–183, 2002. © 2002 Wiley‐Liss, Inc.     

Fertility and pregnancy outcomes in men and women with cystic fibrosis in the United Kingdom

BACKGROUND: The survival of patients with cystic fibrosis (CF) now occurs into the fourth decade of life. Our aim was to evaluate the fertility and pregnancy outcomes of men and women with cystic fibrosis within a large British cohort. METHODS: A population based cohort study of 4659 males and females registered with the UK Cystic Fibrosis Database in 2001. RESULTS: Poor respiratory health (forced expiratory volume in 1 s FEV1 <50%) and CF-related diabetes increased significantly post-puberty compared with childhood. Few individuals with CF sought fertility treatment (1% men, 0.5% women) or achieved pregnancies (1.3% of partners of men, 5.7% women). However, the majority of pregnancies had a good outcome (67% live term birth among male partners, 74% among women). Women who achieved a pregnancy were less likely to suffer from poor respiratory health (FEV1 <50%), age adjusted Odds Ratio 0.6 (95% CI 0.3-0.9), less likely to be homozygous for the DF508 genotype OR 0.5 (95% CI 0.3-0.9) and had a significantly earlier median age at diagnosis (0 years vs 2 years, P=0.001). CONCLUSIONS: Increasing numbers of males and females with cystic fibrosis are reaching reproductive age but currently very few have a child. Optimal adult health should improve the reproductive prognosis for both men and women.     

Biological and behavioral factors influence group differences in prolactin levels among breastfeeding Nepali women

This study of two natural fertility Nepali groups, the Tamang and Kami, identifies biological and behavioral factors associated with population differences in fertility. Previous research had established that Tamang experience longer interbirth intervals than Kami despite similarly intense nursing practices, and bear considerably higher energy expenditure due to workload. This cross-sectional study of 71 breastfeeding women includes prolactin determinations on three blood spot samples collected 5, 30, and 50 minutes following a timed nursing bout, and data on maternal age, BMI, menstrual status, previous birth interval, parity, infant age, nursing bout length, and durations of supplementation and postpartum amenorrhea. The findings show that Tamang breastfeeding mothers have higher average prolactin levels than Kami for as long as 22 months postpartum. Tamang mothers sustain average prolactin levels above those of nonpregnant, nonlactating women for nearly 2 years postpartum, whereas prolactin levels among Kami breastfeeding mothers are the same as this latter group after 1 year postpartum. Furthermore, the findings indicate that Tamang mothers have higher average prolactin levels regardless of maternal age, physical status (BMI, weight, or height), or infant age, and the rate of decline in prolactin from 5 to 50 minutes after suckling is significantly greater for Kami than Tamang. Since factors associated with prolactin levels differ by group, the findings also emphasize that populations vary not only in the strength of effects that proximate determinants have on fertility regulation, but also in the pathways by which they exert their effects (direct physiological versus indirect behavioral). Am. J. Hum. Biol. 10:191–210, 1998. © 1998 Wiley-Liss, Inc.     

Poor semen quality may contribute to recent decline in fertility rates

During past decades, we have witnessed a remarkable decline in fertility rates (number of births per 1000 women of reproductive age) in the industrialized world. It seems beyond doubt that the enormous social changes of our societies play the major role in this decline, but can it be attributed to changing social structures alone or is a reduced fecundity in the population also a factor? To address this we have focused on trends in teenage pregnancies (which to a large extent are unplanned). During the period in question fertility rates among 15-19 year old Danish women have been falling and the decline in fertility rate is not counterbalanced by an increase in the rate of induced abortion. When seen together with recent results from Denmark, which have shown that more than 30% of 19 year old men from the general population now have sperm counts in the subfertile range, we argue that this fall may not be attributable to social factors, changes in conception practices or diminished sexual activity alone. It seems reasonable also to consider widespread poor semen quality among men as a potential contributing factor to low fertility rates among teenagers. Due to the concern caused by the low sperm count among younger Danish men, the Danish Ministries of Health and Environment have launched a surveillance programme which includes an annual examination of the semen quality in 600 young Danes from the general population. We propose that researchers in other countries with low and falling fertility rates among young women should consider the possibility that semen quality of their younger male cohorts may also have deteriorated.     

Modified expression of steroid 5α-reductase as well as aromatase, but not cholesterol side-chain cleavage enzyme, in the reproductive system of male mice during (Taenia crassiceps) cysticercosis

Infection with Taenia crassiceps cysticerci in male mice produces an increase in serum estradiol levels, whereas serum testosterone is abolished. Concomitantly, complete atrophy of the reproductive tract of infected male mice is observed. The present study was undertaken to determine the expression pattern of three key steroidogenic enzymes in the reproductive tissues of normal and infected male mice. In infected mice, serum estradiol levels were increased 97 times as compared with control mice of the same age. Testosterone and dihydrotestosterone levels were completely inhibited. The expression of 5α-reductase in the reproductive tract was markedly reduced, whereas aromatase mRNA levels were highly elevated in the testes of parasitized mice. No change in the mRNA content for cholesterol side-chain cleavage enzyme was evident. The overall results suggest that the change in the normal production of sex steroids in infected male mice is produced concomitantly by the inhibition of expression of the 5α-reductase enzyme and the activation of aromatase gene expression. This induces a preferential metabolism from testosterone to estradiol instead of the normal metabolism from testosterone to dihydrotestosterone. Received: 29 July 1998 / Accepted: 4 November 1998     

Long-term non-hormonal male contraception in mice using N-butyldeoxynojirimycin

BACKGROUND: The imino sugar N-butyldeoxynojirimycin (NB-DNJ) causes reversible infertility in male mice. This compound may have promise as a male contraceptive, because it is already in clinical use, for a non-reproductive condition. As contraceptives need to be taken for extended periods of time, it was essential to evaluate NB-DNJ for its reproductive effects over a long period of administration. METHODS: We have assessed the imino sugar for its long-term effects on the fertility of male C57BL/6 mice, reversibility and potential cumulative toxicity by monitoring various reproductive and systemic parameters over 12 months. RESULTS: Long-term low-dose (15 mg/kg/day) administration of NB-DNJ was sufficient to maintain infertility in male mice. In contrast to short-term drug treatment, imino sugar exposure for more than 3 months resulted in reduced sperm counts. Male mice that had been administered imino sugar for 6, 10 or 12 months and were then maintained without drug administration regained their fertility within 9 weeks after withdrawal of the drug. Prolonged NB-DNJ intake did not affect reproductive hormone levels, serum biochemistry or animal behaviour. CONCLUSION: Low-dose treatment with NB-DNJ over a long period is an effective approach for the regulation of fertility in a male mammal by non-hormonal means, without causing overt adverse effects.     

Current status of reproductive behaviour in Africa

The current annual population growth rate of 3.2% in Africawill double the population by the year 2025. The majority ofthis population is below 15 years of age, and Africa concurrentlyalso has the highest incidence of infertility in the world.Sexual behaviour, which has been poorly studied in Africa, hasa direct impact on reproductive health [including fertility,infertility and sexually transmitted diseases (STDs)]. The multiplecultures and religions which characterize the African continentalso affect reproductive health. Factors that have a significanteffect on reproductive health in Africa include greater prevalenceof extramarital/commercial sexual activity, polygamy, lowerprevalence of contraceptives, reliance on traditional practices,high incidence of STDs and teenage pregnancies. High risk reproductivebehaviours are predominantly displayed by adolescents, and theprevalence of STDs, including HIV (human immunodeficiency virus),is very high in this group. Pregnancy-related complicationsare the major cause of health-related problems in 15-19 yearold girls. Maternal mortality rates in most countries remainhigh. Literacy rates affect these behaviours. It is apparentthat changing the sexual behaviour of adolescents is one wayof reversing the adverse trends, such as STD transmission, unwantedpregnancy and poor general reproductive health.     

Secular trend in the age at menarche in Haiti

Trends in age at menarche of 10,563 pregnant Haitian women enrolled in a longitudinal study of maternal mortality are examined. Mean recalled age at menarche for adult women in the sample was 15.37 years. However, there was a clear decline in mean menarcheal ages from the oldest to the youngest women, with a mean rate of decline for adult women of 0.36 years per decade. Mean menarcheal age was higher in each age group of rural women than for women in the metropolitan Port-au-Prince area; the rate of decline for adult rural women (0.37 years per decade) was nonsignificantly higher than that for adult metropolitan women (0.30 years per decade). The data suggest a secular decline in age at menarche in Haiti, as well as a continuing disparity between metropolitan and rural women. A declining age at menarche has important implications for fertility and reproductive health in Haiti, and may reflect a gradual improvement in health and nutritional status. © 1995 Wiley-Liss, Inc.     

Differential reproductive pattern in a rural Spanish region (La Cabrera, León): Consequences for potential natural selection

La Cabrera (northwest Spain), the study area, during most of the period examined (1880-1969) was characterized by high inbreeding levels and internal subdivision, which probably favoured the action of genetic drift and genetic differentiation. Indices regarding potential selection based on variables related to the reproductive pattern of reconstituted families with complete reproductive cycles (n = 1498) were analysed. A traditional demographic context, characterized by a reduction of mortality resulting in the remarkable increase of number of survivors to reproductive age, is distinguished from a recent context in which survival was similar (approximately 89%) and the fall of mortality and natality proportional. In general, fertility differentials (I(f)) and martality differentials (I(m)) have similar values. Regarding temporal variation, I(m) reduces systematically, with maximum value corresponding to the first decade (1880-1899, I(m) = 0.493) and minimum to the last (1950-1959, I(m) = 0.149). I(f) remains rather stable throughout most of the period studied (1880-1939, I(f) 0.6), increasing slightly in the later decade (1950-1959, I(f) = 0.694). During the years considered, the reproductive pattern in La Cabrera provided an optimal number of offspring by maintaining a balance between high fertility and high pre-reproductive mortality. Despite relaxation of natural selection, it was observed that biological and environmental factors remained active, resulting in high neonatal mortality. However, differential fertility variability, probably reinforced by persistent inbreeding and by the Wahlund effect, explains the differential gene transmission better than does mortality.     

Variability of reproductive history across the Swiss SAPALDIA cohort--patterns and main determinants

BACKGROUND: Reproductive characteristics play an aetiological role for many diseases, including reproductive cancers. They have been shown to vary internationally and nationally, but have not yet been described for the whole Swiss population. AIM: The study investigated the variability of reproductive characteristics, their patterns, and main determinants across a population-based female study population in Switzerland. METHODS: Reproductive characteristics obtained from 3119 women (28-72 years) participating in the SAPALDIA cohort survey in 2001-2003 are described across birth cohorts, study areas, language regions, and levels of urbanization. Determinants of age at menopause were analysed by Cox regression. RESULTS: Reported median age at menarche was 13 years and median age at natural menopause was 52 years. The prevalence of nulliparity was 27%, and the fertility rate 1.6. Across birth cohorts there was a decline of menarcheal age and fertility rates, and an increase of nulliparity and age at last pregnancy. All characteristics varied across study areas, language regions, and levels of urbanization. Smoking, parity, and physical exercise were stronger predictors of earlier (<52 years) than older (>52 years) menopausal age. CONCLUSION: Reproductive events show secular and geographic variation within Switzerland. Smoking, parity and physical activity significantly predict age at natural menopause, particularly before age 52. The secular trend of earlier menarche and increased nulliparity may result in a higher risk of reproductive cancers in younger generations.     

病毒感染与男性不育相关性研究进展

目前研究将病毒感染视为可能影响男性生育力的破坏性因素。男性生殖系统的炎症与不育相关。本文概述了影响男性生殖系统的主要病毒及其对生育力的有害影响。仍需进行大量研究以阐明不同类型的病毒在男性生殖系统中作用的机制,从而开发出更适宜的治疗方案。     

Developmental influences on adult ovarian hormonal function

The hypothesis is advanced that levels of ovarian hormonal function in adult women are associated with the tempo of growth and maturation in childhood and adolescence. Empirical data are presented documenting a correlation between menarcheal age and adult ovarian hormonal function both within and between populations. It is noted that this relationship is compatible with current understanding of the mechanisms underlying pubertal maturation of ovarian hormonal function. Functionally, such a relationship could serve the purpose of modulating adult fecundity to chronic environmental conditions. Alternative hypotheses include the possibility that the relationship is not causal but rather reflects either confounded effects of some common cause or the persistence of acute environmental effects through time. Proper testing of such alternative hypotheses will require longitudinal data on migrant populations, changing environments, or secular trends within populations. The importance of establishing the relationship between development and adult ovarian hormonal function is not limited to issues of fecundity and fertility, but includes other areas of female general and reproductive health. © 1996 Wiley-Liss, Inc.     

When does human ageing begin?

Through much of the 20th century, the low point of human mortality was seen at 12-13 years of age. Its stability and timing have been accorded significance in terms of evolution, maximal fitness and the onset of ageing. The nadir of mortality in developed nations now lies at 5-9 years, significantly predating fertility at a mean of 12-13. This differential fall in mortality has resulted in England and Wales primarily but not exclusively from reductions in accidents and deaths from congenital anomalies. The assumption that the nadir of mortality, onset of fertility and a putative intrinsic point of maximal biological fitness are synchronous is disproved by this shift. In this paper the logic of inferring an individual modal pattern of ageing from mean population behaviour is questioned, and the plausibility of the belief that ageing starts at or after fertility is examined. Biological ageing, whether seen as 'wear and tear', programmed change, or cumulative stochastic damage appears to commence at or before conception. Drawing a distinction between 'intrinsic' and 'extrinsic' mortality makes less sense in early than in late life, but indicators of 'intrinsic' diseases are also present from well before fertility. Similarly, measures of fitness other than mortality risk may also be argued to diminish from before birth.