Evolutionary approach to below replacement fertility

The large human brain, the long period of juvenile dependence, long life span, and male support of reproduction are the co‐evolutionary result of the human niche based on skill‐intensive techniques of resource accrual. The regulation of fertility under traditional conditions is based upon a co‐evolved psychology and physiology where adjustments of investment in offspring depend upon the returns to skill and mortality hazards. When all wealth is somatic, the hormonal system controlling ovulation and implantation translates income into genetic descendants. In modern society the existence of extra‐somatic wealth is a critical condition to which our evolved proximate physiological mechanisms do not respond. However, psychological mechanisms regulating parental investment in offspring quality may lead to greater and greater investment in own and offspring education, a smaller desired family size, a delay in the onset of reproduction, and a reduction in the total numbers of offspring produced. This delay in reproduction can cause many individuals to produce fewer children than desired because fecundity falls during the reproductive part of the life course. As more individuals in a society follow this pattern, more will fail to reach their desired family size. At the same time the effective use of birth control decreases the numbers of families producing more children than desired. Below replacement fertility can result. Predictions from this model were tested using data from the National Survey of Families and Households and the Albuquerque Men study. Am. J. Hum. Biol. 14:233–256, 2002. © 2002 Wiley‐Liss, Inc.     

On the perpetuation of relic genes having an inviable homozygote

Reproductive compensation may be prezygotic or postzygotic. Prezygotic compensation is the replacement of inviable infants by one or more additional births. When the marital fertility rates are greater than necessary to replace the parents, however, many traditional societies ensured that any surviving progeny in excess of two (on average) did not marry, or married only if they replaced an older sib as heir to the family estate. We call this postzygotic compensation. We show that the coefficient of biologically effective compensation approximates unity when normal and genetic-disease-affected sibships were both sufficiently large to ensure that, on average, two or more sibs survived to the end of the reproductive period, irrespective of the level of prezygotic compensation. The impact of these types of compensation on the population genetics of Tay-Sachs disease and cystic fibrosis is discussed.     

肥胖与育龄期女性生殖功能研究进展

女性生殖功能受众多因素影响,肥胖是引起育龄期女性生殖能力降低的重要因素之一.育龄期肥胖女性可表现为月经紊乱,排卵障碍甚至不孕.肥胖与多囊卵巢综合征互为因果.肥胖影响辅助生殖技术的结局,使自然流产的风险增高,影响到妊娠的结局.避免超重及肥胖,积极控制多余体重,提高肥胖女性生育能力.     

Variability in reproductive success viewed from a life‐history perspective in baboons

Nonhuman primates, like humans, mature slowly and have low fertility during a relatively long life. As data have accumulated on life‐history patterns of nonhuman primates, comparative studies have yielded important insights into the evolution of this slow life‐history style of primates. However, in order to understand selection pressures and evolutionary potential within species, it is important to complement comparative studies with detailed studies of life‐history variability within species and to identify sources of this variability. Here we present a summary of how foraging environment, social status, and group size (a measure of population density) contribute to within‐population variance in reproductive success for savannah baboons. We also discuss the extent to which savannah baboons, with their highly flexible and adaptable behavior, change their foraging environments by shifting home ranges and seeking rich food sources and how low‐ranking females, which disproportionately bear the costs of social life, may mitigate those costs. Am. J. Hum. Biol. 15:401–409, 2003. © 2003 Wiley‐Liss, Inc.     

Heritability and anthropometric influences on human fertility

This study researched the impact of anthropometrics and size‐of‐family of orientation on women's fertility by using path analysis. The data were collected as part of the anthropological study conducted in Ireland by Harvard University personnel before the Second World War. The women included in this analysis were all over age 49 and were either married or widowed at the time of the survey. Our results indicate that the heritability of fertility is moderate in this sample and that there is a tendency for heavy women to have a higher fertility. However, when anthropometrics and size‐of‐family of orientation were entered as independent variables in a path diagram, an insignificant portion of the variation of fertility was explained. In this Irish population, the main cause of differential fertility was cultural rather than biological. A large portion of women never married and no unmarried woman reported producing a child. Am. J. Hum. Biol. 15:16–22, 2003. © 2002 Wiley‐Liss, Inc.     

Kin influence on female reproductive behavior: the evidence from reconstitution of the Bejsce parish registers, 18th to 20th centuries, Poland.

The phenomenon of kin-oriented help, according to inclusive fitness theory, should be of crucial importance with respect to the process of reproduction. This is due to the fact that the devoted time and resources might indirectly contribute to the reproductive performance of a donor. This study aimed at analyzing the kin effects on fertility in order to check whether help received from kinsmen enhance a recipient's reproduction in terms of parity transition risk, completed fertility, and the number of survivors. The data came from reconstitution of church registers from Bejsce parish, Poland. To estimate the kin effect, regression models for count outcomes and techniques of multilevel event history analysis were applied. The analyses have shown that completed fertility and parity-specific transition risks are strongly influenced by various kin groups. Moreover, a multilevel hazard model revealed differences in the patterns of the kin influence among controlled fertility than among natural fertility birth cohorts. Female reproductive outcome is influenced mainly by the presence of siblings and postreproductive helpers (grandparents). However, there is a negative impact of so-called helpers-at-the-nest (older children in the household) on parity transition risks.     

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.     

Exposure to terrorism and violent behavior among adolescents in Israel

It is commonly assumed that exposure to terrorism may lead to violent behavior, but there is little empirical research on the relationship between these two variables. In the present paper, we examined the extent to which exposure to terrorism contributes to violent behavior among adolescents. In addition, we considered the role of environmental factors ( domestic and community violence) and personal and environmental resources (family and social support, mastery, hope, and life satisfaction). Two hundred and fifty‐four Israeli adolescents residing in areas with different levels of exposure to terrorism completed questionnaires. The findings confirm that exposure to terrorism contributes significantly to violent behavior. Exposure to domestic and community violence and mastery also contributed to explaining the variance in violent behavior, whereas the effects of hope and life satisfaction were indirect, and were expressed only in an interaction with variables of exposure to terrorism. The findings may be helpful in identifying groups at risk for violent behavior, as well as in guiding professionals to moderate and prevent such behavior. The findings also emphasize the impact of security‐related stress situations and prolonged exposure to terrorism on manifestations of violence. © 2007 Wiley Periodicals, Inc.     

Does polygyny reduce fertility?

Polygyny can increase, decrease, or have no effect on fertility. Understanding how this can occur requires consideration of both the proximate determinants of fertility and the ultimate effects of polygyny as a female reproductive strategy. Several factors reduced the fertility of polygynous women in 19th century Utah, including marrying at an older age, marrying older men, and conflict between co‐wives. Sterility did not explain the reduced number of children in polygynous women, nor is there evidence of a “dilution effect” from sharing a husband. If women could anticipate a reduction in their own fertility, why would they still choose polygyny? Evidence suggests that they chose it because the children of polygynous men had increased fertility, high enough to offset the low fertility of polygynous women themselves. Am. J. Hum. Biol. 14:222–232, 2002. © 2002 Wiley‐Liss, Inc.     

Demographic and medical consequences of the postponement of parenthood

BACKGROUND Across the developed world couples are postponing parenthood. This review assesses the consequences of delayed family formation from a demographic and medical perspective. One main focus is on the quantitative importance of pregnancy postponement. METHODS Medical and social science databases were searched for publications on relevant subjects such as delayed parenthood, female and male age, fertility, infertility, time to pregnancy (TTP), fetal death, outcome of medically assisted reproduction (MAR) and mental well-being. RESULTS Postponement of parenthood is linked to a higher rate of involuntary childlessness and smaller families than desired due to increased infertility and fetal death with higher female and male age. For women, the increased risk of prolonged TTP, infertility, spontaneous abortions, ectopic pregnancies and trisomy 21 starts at around 30 years of age with a more pronounced effects >35 years, whereas the increasing risk of preterm births and stillbirths starts at around 35 years with a more pronounced effect >40 years. Advanced male age has an important but less pronounced effect on infertility and adverse outcomes. MAR treatment cannot overcome the age-related decline in fecundity. CONCLUSIONS In general, women have partners who are several years older than themselves and it is important to focus more on the combined effect of higher female and male age on infertility and reproductive outcome. Increasing public awareness of the impact of advanced female and male age on the reproductive outcome is essential for people to make well-informed decisions on when to start family formation.     

A comparison of economic and social reward in patients with chronic nonmalignant back pain.

OBJECTIVE: Patients with chronic nonmalignant back pain are often exposed to multiple sources of economic and social reward. At issue in the present study was whether these rewards are 1) correlated with similar or dissimilar outcome variables and 2) able to account for unique variance in regression models of illness behavior. METHODS: A 2 x 2 factorial design was used in which patients were retrospectively assigned to one of four independent groups: low economic/low social reward, low economic/high social reward, high economic/low social reward, and high economic/high social reward. Of 265 consecutive patients enrolled at a tertiary pain service, 75 met eligibility criteria and had chronic nonmalignant back pain. RESULTS: Preexisting differences in health status were not associated with differences in illness behavior or pain ratings. With social reward held constant, patients in the high economic reward group missed more days from work (p < .005), had more domestic disability (p < .05), and were more depressed (p < .05) than patients in the low economic reward group. With economic reward held constant, patients in the high social reward group missed more days from work (p < .05), had more domestic disability (p < .01), and were more depressed (p < .01) than patients in the low social reward group. Unlike patients in the high economic reward group, however, patients in the high social reward group had higher levels of pain (p < .05) and more nonspecific medical complaints (p < .01). CONCLUSIONS: Economic and social rewards were both associated with increased disability and depression, but only social rewards were associated with increased symptom reporting. Exposure to economic and social rewards may account for unique variance in illness behavior that cannot be explained by differences in medical diagnosis, symptom duration, pain intensity, depression, or somatization.     

Pregnancy and scleroderma.

Scleroderma is a rare disease with a marked female excess in incidence. The pattern of age of onset, together with the effects of the disease, are such that the majority of women with scleroderma experience pregnancy prior to diagnosis. There are three questions of interest: (1) Does pregnancy adversely affect the prognosis of scleroderma? Isolated case reports suggest that renal disease, and in particular hypertensive crises, are associated with pregnancy in the absence of any renal abnormality before pregnancy. However, such events are rare. (2) Does scleroderma adversely affect either fertility or the outcome of pregnancy? Women with established scleroderma, again in case series, have a high rate of spontaneous miscarriage which is not found consistently in epidemiological studies. Prematurity and low birth rates are more frequent problems. (3) Does reproductive history influence disease and particularly Raynaud's phenomenon may antedate diagnosis by many years and might influence reproductive outcome, in general reproductive outcome is similar to that seen after diagnosis, although fertility appears to be reduced.     

Resilience in Children at High Risk for Psychological Disorder

This longitudinal study examined factors related to healthyadjustment in young children who had experienced conditionsand stresses known to carry a substantial risk of adverse outcome.Psychological adjustment of 109 children at age 6 to 7 yearswas examined for its relationship to infancy risk status, determinedat age 1 month by means of a multifactor screen assessing perinatalstress, psychological problems and stresses in the family, maternalattitudes toward self and parenthood, and maternal perceptionsof infant temperament. Several variables believed to mediateoutcome for high-risk children were studied, including subsequentstressful life events, social support available to child andmother, and child's locus of control orientation. Interactionsbetween predictor variables showed that life events magnifysynergistically the adverse effects of infancy risk factors,and social support and internal control orientation potentlybuffer the effects of risk and stress. Considered jointly inconjunction with their interactions, the predictor variableswere strongly predictive of outcome, explaining 56% of the varianceobserved in behavior problems and 64% of the variance in schoolproblems.     

Examining Psychobiological Responses to an Anticipatory Body Image Threat in Women

The present study extended the applicability of social self‐preservation theory (SSPT) to an anticipatory body image threat. Women (n = 80) were randomized into either a control or threat group (anticipating having a body composition assessment). Participants completed measures of body shame and social physique anxiety (self‐conscious outcomes), and body dissatisfaction (a non‐self‐conscious outcome), and provided a sample of saliva (to assess cortisol levels) at baseline and immediately following their condition. Findings showed that for the threat condition, body image variables were significantly more negative pre‐ to post‐condition. Findings also showed that self‐conscious outcomes were more sensitive than the non‐self‐conscious outcome. There was not a significant group‐by‐time interaction for cortisol. Findings support SSPT's applicability to the anticipation of a social‐evaluative body‐related threat.     

Family‐based prevention counseling for high‐risk young adolescents: Immediate outcomes

Family prevention counseling, which features customized prevention planning for individual families, is a promising approach for preventive intervention with adolescents at high risk for substance abuse and conduct disorder. A randomized study (N = 124) tested the post‐intervention efficacy of an indicated, family‐based prevention model with a sample of inner‐city African‐American youths (ages 11–14). Key risk and protective factors associated with the development of drug use and antisocial behavior were targeted in four domains: self‐competence, family functioning, school involvement, and peer associations. Compared to controls, participants in family prevention counseling showed gains in global self‐worth, family cohesion, and bonding to school, and a decrease in peer antisocial behavior. The potential utility of family prevention counseling within a unified prevention framework is discussed. © 2002 John Wiley & Sons, Inc.     

Helping patterns and reproductive success in Aymara communities

“Helpers at the nest,” young adults remaining in their parents home to take care of younger siblings, are known in many species of birds and mammals. Similar behaviors are occasionally observed in human societies but their frequency and significance for parental reproductive success are still not fully appraised. This study was designed to document this issue in a traditional Aymara peasant society of the Bolivian Altiplano, It is based on 359 reproductive life histories of women 45 years of age or older and on a survey of children's workload in 1998 and 1999. The presence of “potential helpers” in the household is significantly associated with higher fertility and with improved survival of siblings to sexual maturity. Caretaking is not particularly assigned to older daughters. The positive relationship between the availability of offspring help and reproductive success does not demonstrate a causal role for child caretaking because, in contrast with nonhuman helpers, workloads of children range from housekeeping to agricultural tasks, instead of being focused on feeding or protecting younger siblings. Correlation and multiple regression analyses, however, suggest that the total amount of care given by the older offspring and the amount of care received by each recipient are, along with offspring contribution to household economy, among the determinants of parental reproductive success. Am. J. Hum. Biol. 14:372–379, 2002. © 2002 Wiley‐Liss, Inc.     

Psychosocial predictors of distress in parents of children undergoing stem cell or bone marrow transplantation

OBJECTIVE: To examine psychosocial predictors of distress (mood disturbance, perceived stress, caregiver burden) in parents of children undergoing stem cell or bone marrow transplantation (BMT). METHOD: Measures of prior illness experiences, premorbid child behavior problems, family environment, social support, and parental coping behavior were obtained from the resident parents of 151 children prior to the children's admission for BMT. Parents subsequently completed assessments of their mood disturbance, perceived stress, and caregiving burden on a weekly basis through week +6 post-BMT, and then monthly through month +6 post-BMT. RESULTS: Significant changes were observed in parental distress across the course of BMT. After correcting for demographic and medical factors, several significant predictors of parental distress trajectories were identified, including prior parent and patient illness-related distress, premorbid child internalizing behavior problems, the family relationship dimensions of the family environment, and parental avoidant coping behaviors. Multivariable models were developed using a hierarchical modeling approach. The best-fit model accounted for approximately 50% of the variance in parental global distress. CONCLUSIONS: Subgroups of parents at higher risk for increased distress during the acute phase of transplant have been identified. These findings can help target parents who may be in greater need of intervention aimed at reducing transplant-related distress.     

Reproductive decision‐making: a qualitative study among couples at increased risk of having a child with retinoblastoma

Dommering CJ, van den Heuvel MR, Moll AC, Imhof SM, Meijers‐Heijboer H, Henneman L. Reproductive decision‐making: a qualitative study among couples at increased risk of having a child with retinoblastoma. Little is known about the reproductive decision‐making process of couples with an increased risk of having a child with retinoblastoma (Rb). A qualitative study was conducted to explore the impact of prospective risk on reproductive decisions, factors influencing these decisions, and the needs of couples with regard to reproductive counselling. Fourteen couples of childbearing age who received genetic counselling between 2002 and 2006 participated in semi‐structured interviews in 2008. The risk of having a child with Rb ranged from less than 1% to 50%. In most cases, the diagnosis of Rb influenced subsequent family planning. Prenatal diagnosis was used by two couples, while others refrained from having more children. Reproductive decisions were influenced by the burden of the disease for the patient and family members, the impact of ophthalmological screening under anaesthesia, and couples' perceived risk, which did not always relate to their actual risk. Reproductive choices with regard to the number of children wanted changed over time. Our findings indicate topics to be discussed during genetic counselling of couples at increased risk for a child with Rb. We suggest continued access to genetic counselling also after the initial diagnosis and treatment.     

They also serve: Chamorro male fertility in the pre-world war ii period

Male fertility, a generally overlooked aspect in studies of human reproductive patterns, is examined from the reproductive life histories of Chamorro males with essential completed fertility by 1941. Males in this “natural fertility” indigenous population of the Pacific island of Guam exhibit low levels of couple infertility which are counteracted by high levels of adult male mortality, while new unions formed after the death of female partners tend to reduce completed fertility by only about one child. Delayed age at the time of union formation is largely compensated by reduction in birthspacing intervals among offspring of older fathers. Early terminators, formerly fertile couples of reproductive age who fail for unspecified biological or behavioral reasons to continue reproducing, affect an equal or even larger impact than adult male mortality on failure to attain theoretical male fertility maxima in this population. Am. J. Hum. Biol. 10:23–35, 1998. © 1998 Wiley-Liss, Inc.