Paternal age and maternal age are risk factors for miscarriage; results of a multicentre European study

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.

Um filho quando eu quiser?: o caso da França contemporânea

A livre escolha da maternidade e do momento de vivê-la foram reivindicações centrais e unânimes do movimento de mulheres nos anos 1970. Em uma primeira fase, esse embate foi amplamente acompanhado por profissionais da área médica, com a difusão de práticas medicalizadas de contracepção e de aborto. Em contrapartida, as tecnologias reprodutivas que permitem adiar a idade da maternidade foram acolhidas com controvérsias pelas feministas: será que essa medicalização da procriação contribuiria para libertar as mulheres dos limites cronológicos ou, pelo contrário, as confinaria a um destino maternal? É essa questão que esse artigo pretende esclarecer, a partir da experiência social da fecundação in vitro nas duas últimas décadas, sobretudo a realizada em um hospital francês.

Pregnancy-associated hospitalizations in the United States, 1999-2000

OBJECTIVE

The purpose of this study was to examine nondelivery, pregnancy-associated hospitalizations in the United States and the factors associated with them.

STUDY DESIGN

Population-based nondelivery hospitalizations during pregnancy were obtained from the 1999 and 2000 National Hospital Discharge Survey. Ratios of hospitalizations per 100 deliveries were calculated and analyzed by age, race, and payment source.

RESULTS

The pregnancy-associated hospitalization ratio for 1999 through 2000 was 12.8 per 100 deliveries (95% CI, 11.8-13.8). Hospitalizations were highest among young women, African American women, and women without private insurance. Preterm labor, nausea and/or vomiting, and genitourinary complications accounted for one half of antenatal hospitalizations.

CONCLUSION

Pregnancy-associated hospitalizations declined during the 1990s. This may represent a decline in maternal morbidity or a change in management of pregnancy complications. Future research should be expanded to assess trends in morbidity treated in settings outside of hospitals.

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

A possible detrimental paternal age effect on offspring health due to mutations of paternal origin should be reflected in an association between paternal age and fetal loss. The authors used data from a prospective study of 23,821 pregnant women recruited consecutively to the Danish National Birth Cohort from 1997 to 1999 to assess the association between paternal age and fetal death. Fathers of the pregnancies were identified by record linkage to population registers. The paternal age-related risks of fetal death and its components, early and late fetal loss, were estimated using survival analysis. Pregnancies fathered by a man aged 50 or more years (n = 124) had almost twice the risk of ending in a fetal loss compared with pregnancies with younger fathers (hazard ratio = 1.88, 95% confidence interval: 0.93, 3.82), after adjustment for maternal age, reproductive history, and maternal lifestyle during pregnancy. Various approaches to adjustment for potential residual confounding of the relation by maternal age did not affect the relative risk estimates. The paternal age-related risk of late fetal death was higher than the risk of early fetal death and started to increase from the age of 45 years. It should, however, be interpreted cautiously because of the restricted number of fetal deaths.

Late paternity and stillbirth risk

BACKGROUND

The role of paternal ageing on the incidence of some genetic diseases in offspring depends on the hypothesis that spontaneous mutations accumulate due to continuous cell divisions during spermatogenesis. We examined the effect of paternal age on the complex multifactorial character, stillbirth.

METHODS

In 3,619,647 Italian singletons born in 1990-1996 we evaluated stillbirth risk as a function of paternal ageing by means of multiple logistic regression models, which included maternal age and family education, as categorical covariates and interactions. The categorical risk was estimated for mothers and fathers beyond threshold ages of 35 and 40 years, respectively.

RESULTS

Stillbirth risk increases with paternal ageing in mothers > or =30 years old, and maternal age and family education modify the impact. In families with low education, the risk accounts for odds ratio (OR) 1.015 [95% confidence interval (CI) 1.01-1.02] in mothers aged 30-34 years, and for OR 1.032 (95% CI 1.02-1.04) in mothers aged > or =35 years; in families with higher education the risk accounts for OR 1.008 (95% CI 1.00-1.02) and OR 1.025 (95% CI 1.01-1.04), respectively, in mothers aged 30-34 and > or =35 years. In these latter families, for mothers aged <35 and fathers > or =40 years the risk accounts for OR 1.12 (95% CI 1.00-1.25).

CONCLUSIONS

The effect of paternal ageing on stillbirth risk is revealed in mothers aged > or =30 years and is modified by family education. In mothers aged 30-34 years from families with high education, the increase imputable to paternal ageing might be indicative of a genetic component.

The National Women's Health Study: assembly and description of a population-based reproductive cohort

Background

Miscarriage is a common event but is remarkably difficult to measure in epidemiological studies. Few large-scale population-based studies have been conducted in the UK.

Methods

This was a population-based two-stage postal survey of reproductive histories of adult women living in the United Kingdom in 2001, sampled from the electronic electoral roll. In Stage 1 a short "screening" questionnaire was sent to over 60,000 randomly selected women in order to identify those aged 55 and under who had ever been pregnant or ever attempted to achieve a pregnancy, from whom a brief reproductive history was requested. Stage 2 involved a more lengthy questionnaire requesting detailed information on every pregnancy (and fertility problems), and questions relating to socio-demographic, behavioural and other factors for the most recent pregnancy in order to examine risk factors for miscarriage. Data on stillbirth, multiple birth and maternal age are compared to national data in order to assess response bias.

Results

The response rate was 49% for Stage 1 and 73% for the more targeted Stage 2. A total of 26,050 questionnaires were returned in Stage 1. Of the 17,748 women who were eligible on the grounds of age, 27% reported that they had never been pregnant and had never attempted to conceive a child. The remaining 13,035 women reported a total of 30,661 pregnancies. Comparison of key reproductive indicators (stillbirth and multiple birth rates and maternal age at first birth) with national statistics showed that the data look remarkably similar to the general population.

Conclusions

This study has enabled the assembly of a large population-based dataset of women's reproductive histories which appears unbiased compared to the general UK population and which will enable investigation of hard-to-measure outcomes such as miscarriage and infertility.

Epidemiology of male reproductive function: a field searching for tools

BACKGROUND

An increase in the frequency of disorders of the male human reproductive organs has been described over recent decades. Neither its causes nor its consequences on fecundity, the ability of the couples to produce a live child, are clearly known. This lack of knowledge may partly be due to methodological difficulties specific to reproductive epidemiology.

METHODS

We discuss the relevance and limits of some markers of the male aspects of human reproduction, focusing on semen parameters and fecundability, a measure of the probability of pregnancy.

RESULTS

Semen parameters are associated with fecundability, although they have a relatively low sensitivity to detect couples with low fecundability. The study of semen parameters proved central to describe the influence of environmental factors on the male side of reproductive function. The main limitation of semen studies is low participation rates and the possible selection biases ensuing. Fecundability can be estimated by collecting waiting time to pregnancy. Its assessment in retrospective studies often excludes the least fecund, those couples remaining childless, which entails a bias and a decrease in statistical power. The prospective approach and an approach relying on the enrollment of a cross-sectional sample of the couples currently trying to obtain a pregnancy (current duration approach) do not have these limitations. Although it has never been used, the assessment of fecundability using the current duration approach is promising both for aetiologic research and monitoring.

CONCLUSION

Most of the potential markers of male reproductive function are not assessed in the general population of France, with the exception of the incidence rate of testis cancer, which is currently increasing. We present some alternatives for a monitoring system of reproductive function.

Effects of male age on the frequencies of germinal and heritable chromosomal abnormalities in humans and rodents

OBJECTIVE

To review evidence regarding the effects of male age on germinal and heritable chromosomal abnormalities using available human and rodent studies and to evaluate possible underlying mechanisms.

DESIGN

Review of English language-published research using MEDLINE database, excluding case reports and anecdotal data.

RESULT(S)

There was little evidence from offspring or germ cell studies for a generalized male age effect on autosomal aneuploidy, except in rodents. Sex chromosomal nondisjunction increased with age in both human and rodent male germ cells. Both human and rodent data showed age-related increases in the number of sperm with chromosomal breaks and fragments and suggest that postmeiotic cells are particularly vulnerable to the effects of aging. Translocation frequencies increased with age in murine spermatocytes, at rates comparable to mouse and human somatic cells. Age-related mechanisms of induction may include accumulation of environmental damage, reduced efficiency of DNA repair, increased genomic instability, genetic factors, hormonal influences, suppressed apoptosis, or decreased effectiveness of antioxidants and micronutrients.

CONCLUSION(S)

The weight of evidence suggests that the increasing trend toward fathering at older ages may have significant effects on the viability and genetic health of human pregnancies and offspring, primarily as a result of structural chromosomal aberrations in sperm.

Effect of delayed breeding on the reproductive performance of female mice

The aim of the present study was to determine, in the mouse, whether maintaining females as virgins until an advanced reproductive age was associated with decreased reproductive performance and reproductive lifespan compared with females of the same age that were first mated with males at an earlier reproductive age. Randomly selected virgin hybrid (C57BL/6JIco female × CBA/JIco male) female mice were housed individually with a randomly selected 12- to 14-week-old hybrid male either at the age of 28 weeks (normal breeding group; n = 20) or 51 weeks (delayed breeding group; n = 23) for the rest of their reproductive life. Females were checked once daily to determine the day of parturition and to record the litter size and gender of pups at birth for each consecutive litter. At weaning, offspring were weighed and killed. Delayed breeding was associated with smaller litter sizes, both at birth and at weaning, a higher bodyweight of pups at weaning, a higher percentage of litters with at least one newborn pup cannibalised, earlier cessation of female reproductive life and a higher mortality rate of dams during the breeding period. These results show that delayed breeding in the mouse is associated with decreased reproductive performance and a shorter reproductive lifespan compared with females bred at an earlier reproductive age.

Paternal age >or=40 years: an important risk factor for infertility

OBJECTIVE

The purpose of this study was to examine the risk of infertility that is associated with paternal age, because this factor rarely has been investigated, whereas maternal age of >or=35 years is a well-known risk factor.

STUDY DESIGN

This large, retrospective, population-based sample included 6188 European women (from Denmark, Italy, Spain, Germany) aged 25 to 44 years who were selected randomly from census registers in 1991 through 1993.

RESULTS

Among couples composed of a woman aged 35 to 39 years, risks were significantly higher when paternal age was >or=40 years than when paternal age was <40 years, with an adjusted odds ratio of 2.21 (95% CI, 1.13, 4.33) for delay in pregnancy onset (failure to conceive within 12 months) and of 3.02 (95% CI, 1.56, 5.85) for difficulties in having a baby (failure to conceive within 12 months or pregnancy not resulting in a live birth).

CONCLUSION

Like maternal age of >or=35 years, paternal age of >or=40 years should be considered to be a key risk factor for infertility.

Effects of age on DNA double-strand breaks and apoptosis in human sperm

OBJECTIVE

This study was designed to explore the relationship between men's age and DNA damage and apoptosis in human spermatozoa.

DESIGN

Semen samples were collected from men between the ages of 20 and 57 years. Sperm DNA double-strand breaks were assessed using the neutral microgel electrophoresis (comet) assay, and apoptosis was estimated using the DNA diffusion assay.

SETTING

Academic medical center.

PATIENT(S)

Sixty-six men aged 20 to 57 years were recruited from infertility laboratory and general populations and consented to donate a semen sample. Recruitment was determined by time and day of analysis; the only exclusions were for azoospermia, prostatitis, or prior cancer therapy.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

DNA damage and apoptosis in human sperm.

RESULT(S)

Age correlated with an increasing percentage of sperm with highly damaged DNA (range: 0-83%) and tended to inversely correlate with percentage of apoptotic sperm (range: 0.3%-23%). For example, percentage of sperm with highly damaged DNA, comet extent, DNA break number, and other comet measures was statistically significantly higher in men aged 36-57 years than in those aged 20-35 years, but percentage apoptosis was statistically significantly lower in the older group. Semen analysis showed percentage motility to be significantly higher in younger age groups.

CONCLUSION(S)

This study clearly demonstrates an increase in sperm double-stranded DNA breaks with age. Our findings also suggest for the first time an age-related decrease in human sperm apoptosis. These novel findings may indicate deterioration of healthy sperm cell selection process with age.