Advanced paternal age and risk of fetal death: a cohort study

The paternal age effect: a multifaceted phenomenon

Birth rates for older fathers have increased 30% since 1980. When combined with the increased risk for genetic and multifactorial disorders in children conceived by older fathers, paternal age has become an important health issue for modern society. Laboratory research in this area has been minimal, perhaps because of significant experimental barriers, not the least of which is inadequate access to fresh, disease-free human testicular tissue. Regardless, progress has been made and intriguing models supported by experimental evidence have been proposed. The putative mechanisms range from reduced DNA repair activity, leading to increased mutagenesis, to positive selection of germ cells harboring specific disease-causing mutations. There remain many important venues for research in this increasingly relevant phenomenon that impacts future generations.

Analysis of telomere length in couples experiencing idiopathic recurrent pregnancy loss

PURPOSE

Telomere length plays a significant role in various disorders; however, its role in idiopathic recurrent pregnancy loss (iRPL) is not known. The objective of this study was to assess telomere length in peripheral blood leukocytes in couples experiencing unexplained recurrent pregnancy loss (iRPL).

METHODS

The study included 25 couples experiencing iRPL and 20 controls. The mean relative telomere length was measured by quantitative Real Time PCR (Q-PCR) based assay, which measures the average ratio of telomere repeat copy number to a single copy gene (36B4) copy number (T/S ratio) in each sample.

RESULTS

The relative leukocyte mean telomere length (T/S) in both men and women from iRPL group was significantly lower (p < 0.05) when compared to controls. A significant (P < 0.05) negative correlation was found between age and leukocyte telomere length (T/S ratio). Among the sperm parameters seminal volume was found to be negatively (r = -0.4679) associated with the telomere T/S ratio. The DNA fragmentation index of sperm showed positive correlation (r = 0.4744) with telomere length. In this preliminary study, we found that shorter telomere length in both men and women may be associated with early pregnancy loss.

CONCLUSION

In conclusion, shorter telomere length in both male and female partners appears to play a role in the idiopathic recurrent pregnancy loss. Loss of telomeric DNA due to oxidative stress needs further analysis. Analysis of telomere length in germ cells are needed to further substantiate the findings of this study.

Trends in child mortality: a prospective, population-based cohort study in a rural population in south-west Uganda

BACKGROUND

Although there has been substantial global progress in decreasing child mortality over the past two decades, progress in sub-Saharan Africa has largely lagged behind. The temporal trends in child mortality and associated risk factors were investigated in a cohort of children in rural Uganda.

METHODS

Information on children's vital status, delivery, breastfeeding, vaccination history, maternal vital and HIV status, and children's HIV status for 1993-2007 was retrieved from the Medical Research Council/Uganda Virus Research Institute's (MRC/UVRI) Annual Population Census and Survey in Uganda. Regression models were employed to assess the association of these factors with child mortality.

RESULTS

From 1993 to 2007, the death rate (/1000 person-years) in children <13 years of age decreased significantly from 16 to six. Apart from neonates, age-specific death rates fell in all age-groups. A reduction since 1999 in the risk of child mortality was associated with vaccination, birth in a health facility, exclusive breastfeeding for 6 months, 2-3 years since the previous sibling's birth, maternal vital status, and negative mother and child HIV serostatus. Although HIV seropositive children had a 26-fold increased risk of death before 13 years of age, HIV prevalence in children was about 1% and so had a small overall impact on child mortality.

CONCLUSION

These findings are consistent with those of repeated national cross-sectional surveys. Meeting the Millennium Development Goals for child survival in sub-Saharan Africa depends on faster progress in implementing measures to improve birth-spacing, safe delivery in health facilities, infant feeding practices and vaccination coverage.

Characteristics of first-time fathers of advanced age: a Norwegian population-based study

Background

The modern phenomenon of delayed parenthood applies not only to women but also to men, but less is known about what characterises men who are expecting their first child at an advanced age. This study investigates the sociodemographic characteristics, health behaviour, health problems, social relationships and timing of pregnancy in older first-time fathers.

Methods

A cross-sectional study was conducted of 14 832 men who were expecting their first child, based on data from the Norwegian Mother and Child Cohort Study (MoBa) carried out by the Norwegian Institute of Public Health. Data were collected in 2005–2008 by means of a questionnaire in gestational week 17–18 of their partner’s pregnancy, and from the Norwegian Medical Birth Register. The distribution of background variables was investigated across the age span of 25 years and above. Men of advanced age (35–39 years) and very advanced age (40 years or more) were compared with men aged 25–34 years by means of bivariate and multivariate logistic regression analyses.

Results

The following factors were found to be associated with having the first child at an advanced or very advanced age: being unmarried or non-cohabitant, negative health behaviour (overweight, obesity, smoking, frequent alcohol intake), physical and mental health problems (lower back pain, cardiovascular diseases, high blood pressure, sleeping problems, previous depressive symptoms), few social contacts and dissatisfaction with partner relationship. There were mixed associations for socioeconomic status: several proxy measures of high socioeconomic status (e.g. income >65 000 €, self-employment) were associated with having the first child at an advanced or very advanced age, as were several other proxy measures of low socioeconomic status (e.g. unemployment, low level of education, immigrant background).The odds of the child being conceived after in vitro fertilisation were threefold in men aged 34–39 and fourfold from 40 years and above.

Conclusions

Men who expect their first baby at an advanced or very advanced age constitute a socioeconomically heterogeneous group with more health problems and more risky health behaviour than younger men. Since older men often have their first child with a woman of advanced age, in whom similar characteristics have been reported, their combined risk of adverse perinatal outcomes needs further attention by clinicians and researchers.

Paternal age in relation to offspring intelligence in the West of Scotland Twenty-07 prospective cohort study

Background

The adverse effects of advancing maternal age on offspring's health and development are well understood. Much less is known about the impact of paternal age.

Methods

We explored paternal age-offspring cognition associations in 772 participants from the West of Scotland Twenty-07 study. Offspring cognitive ability was assessed using Part 1 of the Alice Heim 4 (AH4) test of General Intelligence and by reaction time (RT).

Results

There was no evidence of a parental age association with offspring RT. However, we observed an inverse U-shaped association between paternal age and offspring AH4 score with the lowest scores observed for the youngest and oldest fathers. Adjustment for parental education and socioeconomic status somewhat attenuated this association. Adjustment for number of, particularly older, siblings further reduced the scores of children of younger fathers and appeared to account for the lower offspring scores in the oldest paternal age group.

Conclusion

We observed a paternal age association with AH4 but not RT, a measure of cognition largely independent of social and educational experiences. Factors such as parental education, socioeconomic status and number of, particularly older, siblings may play an important role in accounting for paternal age-AH4 associations. Future studies should include parental intelligence.

The effect of paternal age on fetal birth outcomes

Research investigating the role of paternal age in adverse birth outcomes is limited. This population-based retrospective cohort study used the Missouri maternally linked data set from 1989 to 2005 to assess whether paternal age affects fetal birth outcomes: low birth weight (LBW), preterm birth (PTB), stillbirth, and small size for gestational age (SGA). We examined these outcomes among infants across seven paternal age-groups (<20, 20-24, 25-29, 30-34, 35-39, 40-45, and >45 years) using the generalized estimating equation framework. Compared with infants born to younger fathers (25-29 years), infants born to fathers aged 40 to 45 years had a 24% increased risk of stillbirth but a reduced risk of SGA. A 48% increased risk of late stillbirth was observed in infants born to advanced paternal age (>45 years). Moreover, advanced paternal age (>45 years) was observed to result in a 19%, 13%, and 29% greater risk for LBW, PTB, and VPTB (very preterm birth) infants, respectively. Infants born to fathers aged 30 to 39 years had a lower risk of LBW, PTB, and SGA, whereas those born to fathers aged 24 years or younger had an elevated likelihood of experiencing these same adverse outcomes. These findings demonstrate that paternal age influences birth outcomes and warrants further investigation.

Germ cell DNA-repair systems-possible tools in cancer research?

A major dogma in cancer research is that cancer begins at the cellular level. Because of this single-cell origin, evolutionary principles have often been used to explain how somatic cancer cells are selected at a sub-individual level. The traditional application of Darwinian theory, however, in which the colony of cells constituting an individual is regarded as a whole, has not been applied extensively to the understanding of cancer until recently. Two proponents for this view, Breivik and Gaudernack, have suggested that in certain situations the cost of DNA repair might exceed the cost of errors. This model predicts that genetic stability is configured for an optimal cost-benefit relationship. Natural selection is not expected to have produced the best genetic stability available in the human body, merely the best compromise of DNA repair and costs. Repair and maintenance of the vast human genome is thermodynamically expensive, and an optimal balance between DNA repair and dietary needs is likely to have originated. Furthermore, fast growth conveys significant advantages such as early maturation or cognitive development, but usually at the expense of replication accuracy. Thus, a compromise between growth speed and cancer risk is likely to have taken place. These and other ecological mechanisms have probably prevented genomic stability to reach its full potential in the human body. In contrast, germ lines express near perfect DNA maintenance. Although germ cells are specialized DNA-conserving cells with few other functions, it's not given that their proteins will all be incompatible with the somatic cell. One approach to study this would be to systematically explore which DNA-stability and -repair systems are unique in germ cells, and induce their expression in invertebrate and mammalian model organisms. This could unveil which DNA-repair systems are switched off in the somatic cell lines, as they are incompatible, and which are absent due to evolution. The present review discuss different DNA-repair systems and cell cycle check point control mechanisms shown to be different or unique in the germ cell, and how they may be utilized in cancer therapy.

Advanced paternal age and reproductive outcome

Women have been increasingly delaying the start of motherhood in recent decades. The same trend is seen also for men. The influence of maternal age on fertility, chromosomal anomalies, pregnancy complications, and impaired perinatal and post-natal outcome of offspring, has been thoroughly investigated, and these aspects are clinically applied during fertility and pregestational counseling. Male aging and reproductive outcome has gained relatively less attention. The purpose of this review is to evaluate updated and relevant literature on the effect of paternal age on reproductive outcome.

The Danish National Birth Cohort: selected scientific contributions within perinatal epidemiology and future perspectives

INTRODUCTION

In this review a selection of studies published during the period 2002-2010, based on data from the Danish National Birth Cohort linked with other health registers, is described. Illustrative examples of studies addressing perinatal health outcomes (pregnancy complications and fetal and infant health) of a variety of exposures during pregnancy, as well as examples showing different methodological approaches in design and analyses of the studies, are presented.

RESEARCH TOPICS

The exposures of interest include alcohol drinking, coffee intake, smoking, use of nicotine substitutes, physical exercise, working conditions, medication and infections during pregnancy, and environmental possible toxins. The study designs cover straightforward cohort analyses, case-control studies and sub-cohort analyses with enriched data collection.

CONCLUSION

So far, the Danish National Birth Cohort has provided important knowledge for evidence-based antenatal care by giving more accurate risk estimates for adverse pregnancy outcomes associated with the exposures of interest. Some new potential hazardous exposures during pregnancy have been identified and others have been put to rest. We believe that this investment in epidemiologic infrastructure was well spent. The existence of the Danish National Birth Cohort together with other cohorts and national registers has given Denmark a leading position in reproductive epidemiology.

[Prognosis criteria for the management of the infertile couple]

Advanced maternal age, obesity and cigarette smoking are associated with decreased fertility, adverse Assisted Reproductive Technologies (ART) outcomes and fetal and neonatal complications. IVF failures increase dramatically in women aged between 42-43 years. Advanced paternal age is associated with fetal and neonatal adverse outcomes. However, it remains uncertain that advanced paternal age could impair IVF results. Obesity (Body mass index more than 30 kg/m(2)) is associated with lower fecundity, pregnancy complications and adverse ART results. The rate of complications is increasing with higher BMI. Cigarette smoking is associated with longer time to conceive and decreased IVF results. In case of infertility associated with obesity or cigarette smoking, physicians have to inform their patient about the benefits of smoking cessation and weight loss. However, maternal age had to be considered as the main prognosis factor before delaying ART because of dietary or smoking cessation program.

Major risk factors for stillbirth in high-income countries: a systematic review and meta-analysis

BACKGROUND

Stillbirth rates in high-income countries have shown little or no improvement over the past two decades. Prevention strategies that target risk factors could be important in rate reduction. This systematic review and meta-analysis was done to identify priority areas for stillbirth prevention relevant to those countries.

METHODS

Population-based studies addressing risk factors for stillbirth were identified through database searches. The factors most frequently reported were identified and selected according to whether they could potentially be reduced through lifestyle or medical intervention. The numbers attributable to modifiable risk factors were calculated from data relating to the five high-income countries with the highest numbers of stillbirths and where all the data required for analysis were available. Odds ratios were calculated for selected risk factors, from which population-attributable risk (PAR) values were calculated.

FINDINGS

Of 6963 studies initially identified, 96 population-based studies were included. Maternal overweight and obesity (body-mass index >25 kg/m(2)) was the highest ranking modifiable risk factor, with PARs of 8-18% across the five countries and contributing to around 8000 stillbirths (≥22 weeks' gestation) annually across all high-income countries. Advanced maternal age (>35 years) and maternal smoking yielded PARs of 7-11% and 4-7%, respectively, and each year contribute to more than 4200 and 2800 stillbirths, respectively, across all high-income countries. In disadvantaged populations maternal smoking could contribute to 20% of stillbirths. Primiparity contributes to around 15% of stillbirths. Of the pregnancy disorders, small size for gestational age and abruption are the highest PARs (23% and 15%, respectively), which highlights the notable role of placental pathology in stillbirth. Pre-existing diabetes and hypertension remain important contributors to stillbirth in such countries.

INTERPRETATION

The raising of awareness and implementation of effective interventions for modifiable risk factors, such as overweight, obesity, maternal age, and smoking, are priorities for stillbirth prevention in high-income countries.

FUNDING

The Stillbirth Foundation Australia, the Department of Health and Ageing, Canberra, Australia, and the Mater Foundation, Brisbane, Australia.

Time-to-pregnancy and risk of schizophrenia

Schizophrenia has been linked to advanced paternal age, but the explanation is unknown. We questioned whether the incidence of schizophrenia would be related to male reproductive capacity, as reflected in the time taken to conceive. We measured the incidence of schizophrenia in relation to time to conception in a sub-group of 12,269 in the Jerusalem cohort whose mothers, interviewed post-partum, reported that the pregnancy had been intended. Compared with those conceived in less than 3 months, the unadjusted relative risks (RR) of schizophrenia associated with conception-waits of 3-5, 6-11 and 12+ months were 1.10 (95% confidence interval, 0.62-1.94), 1.41 (0.79-2.52) and 1.88 (1.05-3.37) with p for trend=0.035. This trend was attenuated somewhat by adjusting for paternal age, and was observed more strongly in offspring of fathers aged 30+ (p=.010). These findings suggest that factors associated with fecundability, either male or female, may contribute to the risk of schizophrenia.

Why do women not prefer much older men? a hypothesis based on alterations in male reproductive physiology related to increased age

Evolutionary Psychology studies suggest that women prefer slightly older or similarly aged partners, although to date few hypotheses have been put forth to explain this pattern of choice. Several recent studies have shown changes in male reproductive parameters as a result of increased age. In the current review of medical literature, we found evidence that much older men are more likely to be infertile, women with much older partners are more likely to experience problems during pregnancy, and children of much older men are more likely to have genetic abnormalities. Based on these findings, we suggest that reproducing with much older men does not represent the best reproductive option for women, which would explain the female preference for only slightly older or similarly-aged mates.

Paternal age increases the risk for autism in an Iranian population sample

Background

Autism is a neurodevelopmental disorder which is known to have a strong genetic component and is most likely oligogenic. However, the necessary role of environmental factors has been well documented. Prior research suggests that parental characteristics, such as age and level of education, may be associated with a risk of autism. Parental age has been shown to be associated with many disorders, such as schizophrenia, childhood cancer and fetal death. However, results from studies of parental age and autism are inconsistent.

Methods

In the present study, we investigated the association of autism with parental age in 179 autism cases and 1611 matched cohort children from Iran. Each case was matched with nine cohort controls on parental education, sex, order of birth, consanguineous marriage, urbanism and province of residence. The Cox regression model was used to carry out conditional logistic regression on the matched data.

Results

There was a significant association between higher paternal age, but not maternal age, and an increasing risk of autism. An analysis of the combined effect of parental age and education also revealed that parents with higher education had an increased risk of having autistic children, with a dose-response effect of parental age.

Conclusions

This study, which is the first epidemiological study of autism in Iran, provides evidence of the association of paternal age and risk of autism.

Independent and dependent contributions of advanced maternal and paternal ages to autism risk

Reports on autism and parental age have yielded conflicting results on whether mothers, fathers, or both, contribute to increased risk. We analyzed restricted strata of parental age in a 10-year California birth cohort to determine the independent or dependent effect from each parent. Autism cases from California Department of Developmental Services records were linked to State birth files (1990-1999). Only singleton births with complete data on parental age and education were included (n=4,947,935, cases=12,159). In multivariate logistic regression models, advancing maternal age increased risk for autism monotonically regardless of the paternal age. Compared with mothers 25-29 years of age, the adjusted odds ratio (aOR) for mothers 40+ years was 1.51 (95% CI: 1.35-1.70), or compared with mothers <25 years of age, aOR=1.77 (95% CI, 1.56-2.00). In contrast, autism risk was associated with advancing paternal age primarily among mothers <30: aOR=1.59 (95% CI, 1.37-1.85) comparing fathers 40+ vs. 25-29 years of age. However, among mothers >30, the aOR was 1.13 (95% CI, 1.01-1.27) for fathers 40+ vs. 25-29 years of age, almost identical to the aOR for fathers <25 years. Based on the first examination of heterogeneity in parental age effects, it appears that women's risk for delivering a child who develops autism increases throughout their reproductive years whereas father's age confers increased risk for autism when mothers are <30, but has little effect when mothers are past age 30. We also calculated that the recent trend towards delayed childbearing contributed approximately a 4.6% increase in autism diagnoses in California over the decade.

Advanced paternal age is associated with impaired neurocognitive outcomes during infancy and childhood

BACKGROUND

Advanced paternal age (APA) is associated with an increased risk of neurodevelopmental disorders such as autism and schizophrenia, as well as with dyslexia and reduced intelligence. The aim of this study was to examine the relationship between paternal age and performance on neurocognitive measures during infancy and childhood.

METHODS AND FINDINGS

A sample of singleton children (n = 33,437) was drawn from the US Collaborative Perinatal Project. The outcome measures were assessed at 8 mo, 4 y, and 7 y (Bayley scales, Stanford Binet Intelligence Scale, Graham-Ernhart Block Sort Test, Wechsler Intelligence Scale for Children, Wide Range Achievement Test). The main analyses examined the relationship between neurocognitive measures and paternal or maternal age when adjusted for potential confounding factors. Advanced paternal age showed significant associations with poorer scores on all of the neurocognitive measures apart from the Bayley Motor score. The findings were broadly consistent in direction and effect size at all three ages. In contrast, advanced maternal age was generally associated with better scores on these same measures.

CONCLUSIONS

The offspring of older fathers show subtle impairments on tests of neurocognitive ability during infancy and childhood. In light of secular trends related to delayed fatherhood, the clinical implications and the mechanisms underlying these findings warrant closer scrutiny.

[Causes and clinical implications of sperm DNA damages]

Numerous recent studies involve DNA damages associated with poor fertilization rates, early embryo development defect, and poor quality of conceptus following Assisted Reproductive Technologies (ART). The authors denounce a particularly high rate of miscarriages and childhood cancer or dominant genetic mutations such as achondroplasia, Apert syndrome or aberrant gene imprinting such as Angelman and Beckwith Wiedeman syndromes. Gametes DNA defects have numerous origins which are difficult to determine; they are known to involve hypomethylation, oxydative stress and environmental factors.(adducts formation). DNA defect is also linked to a more or less delayed apoptotic phenomenon. Exposure to radiations or radiofrequency electromagnetic emissions can also induce DNA alterations into the spermatozoa of infertile men. Although the underlying mechanisms are unclear, these DNA defects have obvious consequences on reproduction of mammalian species. Detection of such anomalies before ART, are an important step toward developing strategies for clinical management according to the aetiology.

Advanced paternal age: how old is too old?

Average paternal age in the UK is increasing. The public health implications of this trend have not been widely anticipated or debated. This commentary aims to contribute to such a debate. Accumulated chromosomal aberrations and mutations occurring during the maturation of male germ cells are thought to be responsible for the increased risk of certain conditions with older fathers. Growing evidence shows that the offspring of older fathers have reduced fertility and an increased risk of birth defects, some cancers, and schizophrenia. Adverse health outcomes should be weighed up against advantages for children born to older parents, mindful that these societal advantages are likely to change over time.

Late fetal death in offspring and subsequent incidence of prostate cancer in fathers: the Jerusalem Perinatal Study cohort

BACKGROUND

Little is known of the causes of prostate cancer and few previous studies have investigated men's reproductive histories in relation to this disease. We sought to determine whether risk of prostate cancer was altered in men who had fathered stillborn offspring.

METHODS

We studied the incidence of prostate cancer (N = 252) in a cohort of 15,268 fathers followed for 28-41 years from the birth of a live offspring, whose wives participated in one of two separate surveys of outcomes of previous births. Proportional hazards models were used to estimate relative risks (RR) associated with previous stillbirths, controlling for changes in incidence over time, social and occupational factors.

RESULTS

The 543 men with one or more stillborn offspring experienced an increased risk of prostate cancer (adjusted RR = 1.87, 95% confidence interval = 1.17-3.00, P = 0.0095), compared to men without stillbirths. With one reported stillbirth, the RR was 1.68 (0.99-2.84); with two or more, the RR was 3.29 (1.22-8.88). Results were consistent in men whose wives were interviewed in 1965-1968 and 1974-1976. In 100 fathers with no male offspring and at least one stillbirth the RR was 4.04 (1.87-8.71, P = 0.0004).

CONCLUSIONS

These findings should be considered hypothesis-generating and require confirmation in other studies. They suggest that stillbirth and prostate cancer may have shared environmental causes; alternatively, genetic susceptibility to prostate cancer might increase the risk of a stillbirth in offspring.

Risk factors for first trimester miscarriage--results from a UK-population-based case-control study

OBJECTIVE

The aim of this study was to examine the association between biological, behavioural and lifestyle risk factors and risk of miscarriage.

DESIGN

Population-based case-control study.

SETTING

Case-control study nested within a population-based, two-stage postal survey of reproductive histories of women randomly sampled from the UK electoral register.

POPULATION

Six hundred and three women aged 18-55 years whose most recent pregnancy had ended in first trimester miscarriage (<13 weeks of gestation; cases) and 6116 women aged 18-55 years whose most recent pregnancy had progressed beyond 12 weeks (controls).

METHODS

Women were questioned about socio-demographic, behavioural and other factors in their most recent pregnancy.

MAIN OUTCOME MEASURE

First trimester miscarriage.

RESULTS

After adjustment for confounding, the following were independently associated with increased risk: high maternal age; previous miscarriage, termination and infertility; assisted conception; low pre-pregnancy body mass index; regular or high alcohol consumption; feeling stressed (including trend with number of stressful or traumatic events); high paternal age and changing partner. Previous live birth, nausea, vitamin supplementation and eating fresh fruits and vegetables daily were associated with reduced risk, as were feeling well enough to fly or to have sex. After adjustment for nausea, we did not confirm an association with caffeine consumption, smoking or moderate or occasional alcohol consumption; nor did we find an association with educational level, socio-economic circumstances or working during pregnancy.

CONCLUSIONS

The results confirm that advice to encourage a healthy diet, reduce stress and promote emotional wellbeing might help women in early pregnancy (or planning a pregnancy) reduce their risk of miscarriage. Findings of increased risk associated with previous termination, stress, change of partner and low pre-pregnancy weight are noteworthy, and we recommend further work to confirm these findings in other study populations.

How old is too old for fertility treatment?

Women are delaying starting their families. High-profile women such as Cherie Blair and Madonna are having successful pregnancies with healthy babies in their forties. Is this sending out messages to women that delaying conception during their twenties and thirties is a good idea? Fertility treatment can overcome certain age-related hurdles but is certainly not the magic wand some expect it to be.

Origins and consequences of DNA damage in male germ cells

DNA damage in the male germline is associated with poor fertilization rates following IVF, defective preimplantation embryonic development, and high rates of miscarriage and morbidity in the offspring, including childhood cancer. This damage is poorly characterized, but is known to involve hypomethylation of key genes, oxidative base damage, endonuclease-mediated cleavage and the formation of adducts with xenobiotics and the products of lipid peroxidation. There are many possible causes of such DNA damage, including abortive apoptosis, the oxidative stress associated with male genital tract infection, exposure to redox cycling chemicals, and defects of spermiogenesis associated with the retention of excess residual cytoplasm. Physical factors such as exposure to radiofrequency electromagnetic radiation or mild scrotal heating can also induce DNA damage in mammalian spermatozoa, although the underlying mechanisms are unclear. Ultimately, resolving the precise nature of the DNA lesions present in the spermatozoa of infertile men will be an important step towards uncovering the aetiology of this damage and developing strategies for its clinical management.

The male biological clock

Do men have biological clocks that affect their hormone levels, fertility, and the genetic quality of their sperm? Women can no longer be viewed as solely responsible for age-related fertility and genetic problems. The effects of andropause and advanced paternal age on fertility and offspring are still under investigation. Further research is needed to fully characterize the associated risks and to treat the underlying abnormalities. A better understanding of the cellular and biochemical mechanisms of "gonadal" aging is important in order to determine safe, effective ways to delay this process and "rewind" the male biological clock. The benefits may include decreasing the potential for adverse genetic consequences in offspring, improvement in the sexual and reproductive health of aging males, and increase a woman's chance of having healthy children by correcting defects in the male reproductive system.

Paternal age and spontaneous abortion

OBJECTIVE

To evaluate the influence of paternal age upon spontaneous abortion.

METHODS

This case-control study of 13,865 women draws on data from women's antenatal or postpartum interviews in the Jerusalem Perinatal Study, a population-based cohort derived from 92,408 births in 1964-1976. Case women (n=1,506) reported spontaneous abortion in the pregnancy preceding the interview; they were compared with women reporting live births in their previous pregnancy (n=12,359). Logistic regression was used to adjust for maternal age, maternal diabetes, maternal smoking, history of spontaneous abortions before the index pregnancy, parity at interview, and interval between the index pregnancy and the interview.

RESULTS

The adjusted odds ratio for spontaneous abortion was 0.59 (95% confidence interval 0.45-0.76, P< .0001) for pregnancies conceived from fathers aged younger than 25 years compared with those from fathers aged 25-29 years. For fathers age 40 years or older the odds ratio for spontaneous abortion was 1.6 (95% confidence interval 1.2-2.0, P=.0003) when compared with the same reference group.

CONCLUSION

Increasing paternal age is significantly associated with spontaneous abortion, independent of maternal age and multiple other factors.

Fathers over 40 and increased failure to conceive: the lessons of in vitro fertilization in France

OBJECTIVE

To investigate paternal age effect mediated by biological modifications with use of data from assisted reproductive technologies.

DESIGN

National IVF registry.

SETTING

Fifty nine French IVF centers.

PATIENT(S)

A total of 1,938 men whose partners were totally sterile, with bilateral tubal obstruction or absence of both tubes (to avoid bias sampling in analysis of paternal age) and treated by conventional IVF.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Risk of failure to conceive defined as absence of intrauterine pregnancy.

RESULT(S)

The odds ratio of failure to conceive for paternal age > or =40 years was 2.00 (95% confidence interval [CI]: 1.10-3.61) when the woman was 35-37 years old, 2.03 (95% CI: 1.12-3.68) for age 38-40 years, and 5.74 (95% CI: 2.16, 15.23) for age 41 years and over.

CONCLUSION(S)

As an increasing number of couples choose to postpone childbearing, they should be informed that paternal age over 40 years is an important risk factor for failure to conceive.

The evolutionary role of erectile dysfunction

Biologic processes that affect the ability of an organism to reproduce are subject to heavy evolutionary pressure. Erectile dysfunction (ED), a common condition in elderly males, definitely affects the ability of the organism to reproduce, and therefore, it is expected to play a significant evolutionary role. Whereas oogenesis is limited to young females, spermatogenesis is a lifelong process. As a male gets older, the number of (pre-meiotic) mitotic cell divisions during spermatogenesis increases, as does the risk of de novo gene mutations. In this paper, I examine the hypothesis that ED, in addition to decrease in fertility, are two evolutionary safety mechanisms that reduce the probability of an ovum being fertilized with genetically altered sperm from an aged or sick male. This hypothesis is supported by the parallel rise in the occurrence of ED, infertility, and risk of congenital anomalies with age; by the occurrence of these three processes in the same medical conditions; and by the presence of a theory unifying the etiologies of three processes-the "free radical theory of aging". This hypothesis can predict the occurrence of congenital anomalies under conditions associated with ED and infertility but are presently not known to be associated with congenital anomalies.

Influence of paternal age on the risk of spontaneous abortion

The frequency of chromosomal anomalies in spermatozoa appears to increase with male age. Because these anomalies play a role in the etiology of spontaneous abortion, an influence of paternal age on risk of spontaneous abortion is plausible but not established. The aim was to characterize this influence in a prospective study among 5,121 California women, who as members of a prepaid health plan were interviewed in 1990 or 1991 when they were less than 13 weeks' pregnant and who were followed until the end of pregnancy. The risk of spontaneous abortion between weeks 6 and 20 of pregnancy was studied using a Cox model adjusted for maternal age. The adjusted hazard ratio of spontaneous abortion associated with paternal age of 35 years or more, compared with less than 35 years, was 1.27 (95% confidence interval: 1.00, 1.61), with no modification by maternal age. Among women aged less than 30 years, the hazard ratio of spontaneous abortion associated with paternal age of 35 years or more was 1.56 for first trimester spontaneous abortion and 0.87 for early second trimester spontaneous abortion (test of interaction, p = 0.25). In conclusion, the risk of spontaneous abortion increased with increasing paternal age, with a suggestion that the association is stronger for first trimester losses.