Long-term effects of delayed motherhood in mice on postnatal development and behavioural traits of offspring.
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BACKGROUND: Some epidemiological evidence tentatively suggests that children born to older parents may have lower intellectual development and maturity than children whose parents are younger. This study aims to analyse the long-term effects of delayed motherhood in mice on postnatal development and behavioural traits later in life. METHODS: Hybrid females, either at the age of 10 weeks or 51 weeks, were individually housed with a randomly selected 12-14 week old hybrid male. After a postweaning resting period of 1 week, dams were caged again with a new randomly selected 12-14 week old male. This sequence of events was repeated until old females reached the end of their reproductive life. RESULTS: Delayed motherhood in mice not only had negative effects on reproductive potential but also on preweaning development of offspring as evidenced by higher mortality, retarded sensorimotor integration and lower body weights as well as on behavioural traits of young adult offspring including decreased spontaneous motor activity, lower step-through latencies in the retention trial of a passive avoidance behaviour test, and no changes in escape latencies throughout five daily sessions in a Morris water maze test. CONCLUSION: Advanced maternal age at conception may influence preweaning development and learning capacity of offspring in the mouse model. (+info)
Effects of season of birth on reproduction in contemporary humans: brief communication.
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BACKGROUND: At high latitudes the external environment varies with season, and therefore the season of birth may contribute to the developmental processes during the perinatal period. METHODS: We investigated the association between birth season and measures of reproductive performance (offspring count, percentage childless individuals) in a contemporary sample of women and men. RESULTS: In the male sample (n = 2342), men born in autumn had fewer offspring (mean 1.4 versus 1.62; P < 0.01) and a higher probability of remaining childless (32.6% versus 25.6%; P = 0.01) than men born in spring. The photoperiod at a male's birth was significantly positively correlated with his subsequent offspring count (P = 0.023). In the female sample, an association between birth season and reproduction was not found. CONCLUSIONS: We assume that in men, among other seasonal factors, pre- or perinatal photoperiod might be involved in the underlying physiological mechanism. (+info)
Compression of women's reproductive spans in Andhra Pradesh, India.
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CONTEXT: The total fertility rate in Andhra Pradesh, India, has recently decreased to near-replacement level; however, the reasons for the fertility decline are unknown. METHODS: Data from the second round of the National Family Health Survey were used to examine the reproductive span-the duration between first marriage and menopause or sterilization-among 4,032 ever-married women aged 15-49 living in Andhra Pradesh in 1998-1999. RESULTS: Between 1992-1993 and 1998-1999, the median age at which women married remained at 15.1, whereas the age at which they adopted sterilization decreased from 24.5 to 23.6. In life-table analyses, reproductive spans of successive cohorts of women decreased-from 22 years among those who married during the 1960s to 15 years among those who married in the 1970s, 10 years among those who married in the 1980s and five years among those who married in 1990-1996. Proportional hazards regression analyses that controlled for demographic and social characteristics, as well as reproductive attitudes, confirmed this cohort effect (hazard ratios, 1.5-2.6). CONCLUSIONS: These findings suggest that women are making the decision to end childbearing faster than older generations did. The gradual compression in reproductive spans is attributable mainly to sterilization acceptance among younger women. (+info)
BACKGROUND: Season of birth has been reported to affect later reproduction in samples of pre-modern women and contemporary men. METHODS: To examine whether the effect of birth date is also valid in contemporary women, we investigated the association between birth month and measures of reproductive performance (number of live-born children, % childless individuals) in a representative sample of contemporary Austrian women. RESULTS: Among reproducing women, birth month is significantly associated with the number of live-born children (n = 2839, P = 0.032). On average, women born in summer months have fewer children than women born during the remainder of the year. No association between birth month and the percentage of childless individuals was found. CONCLUSIONS: As has been reported in pre-modern women, month of birth also appears to affect later reproduction in contemporary women. (+info)
Hormones and history: the evolution and development of primate female sexuality.
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Sexual behavior is required for reproduction in internally fertilizing species but poses significant social and physical risks. Females in many nonprimate species have evolved physical and behavioral mechanisms restricting sexual behavior to when females are fertile. The same hormones producing female fertility also control these mechanisms, assuring that sex only occurs when reproduction is possible. In contrast to nonprimate mammals, hormones do not regulate the capacity to engage in sex in female anthropoid primates, uncoupling fertility and the physical capacity to mate. Instead, in primates, sexual motivation has become the primary coordinator between sexual behavior and fertility. This dependence upon psychological mechanisms to coordinate physiology with behavior is possibly unique to primates, including humans, and allows a variety of nonphysiological influences, particularly social context, to regulate sexual behavior. The independence between hormonal state and sexual behavior allows sex to be used for social purposes. This complex regulation of primate sexuality develops during adolescence, where female monkeys show both hormonally influenced sexual motivation and socially modulated sexual behavior. We present findings from rhesus monkeys illustrating how social context and hormonal state interact to modulate adolescent and adult sexuality. It is argued that this flexibility in sexual behavior, combined with a tight regulation of sexual motivational systems by reproductive hormones, allows sexual behavior to be used for nonreproductive purposes while still assuring its occurrence during periods of female fertility. The evolutionary pressures that produced such flexibility in sexual behavior remain puzzling, but may reflect the importance of sexuality to primate social attraction and cohesion. (+info)
Response to: A rational cure for pre-reproductive stress syndrome.
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This response to "A rational cure for pre-reproductive stress syndrome" first suggests it is existence that is essential and prerequisite to everything good or bad, therefore it deserves to be protected and respected. Secondly, it argues that every life is worth living, even if it is worse than some other lives, if the only alternative is non-existence. Finally, it takes a critical view of and challenges Hayry's suggestion that in a good clinical situation, the idea of the irrationality of having children could be a legitimate part of the guidance given, since it is not the counsellor's or doctor's duty to advise a couple who wish to have children that it is irrational or even immoral to bring a child into life. (+info)
Woman wants dead fiance's baby: who owns a dead man's sperm.
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The Brisbane Supreme Court has denied an Australian woman's request to harvest and freeze her dead fiance's sperm for future impregnation. After she was denied access to the sperm, the woman learnt that her fiance may have been a sperm donor and she began checking to find out if his sperm was still available. Given what we know, there is a good ethical argument that the woman should have access to the sperm and should be allowed to have her dead fiance's child. Another aspect of this case is that it illustrates the way in which ethics, law, and personal opinion can differ. (+info)
Evaluating men's involvement as a strategy in sexual and reproductive health promotion.
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Nearly 10 years has passed since the 1994 International Conference on Population and Development recognized men as legitimate targets for sexual and reproductive health promotion. This recognition was born of the experience of many health promoting agencies in the 1980s and 1990s who realized that without working with men, change would be very difficult or impossible. It was proposed that men should be involved because their active participation was crucial to the success of programs and to the empowerment of women. However, the idea that men should play an active role in health promotion has not been without its critics, who have posed serious questions about the efficacy of involving men and the effects their involvement would have on women and children. In an effort to examine the lessons learned from men's involvement, this paper reviews published evaluations of interventions that have targeted heterosexual men. Twenty-four studies that met the criteria for inclusion (reported on interventions in areas of sexual and reproductive health that targeted heterosexual men and contained evaluation data) were found. From their review of these studies, the authors suggest that there is some evidence that the use of media approaches may be a successful strategy and that there may be some problems with the application of some cognitive behavior change approaches. However, the fact that few interventions have targeted heterosexual men and have been the subject for detailed evaluation suggests that there is a need for more interventions and better evaluations, which would examine not only the process of men's involvement, but also their impact on the lives of both the men themselves and their families. The reality is that although perhaps no longer regarded as part of the problem, men have yet to be seen as part of the solution. (+info)