Advancing Paternal Age Is Associated with Deficits in Social and Exploratory Behaviors in the Offspring: A Mouse Model

Advancing Paternal Age Is Associated with Deficits in Social and Exploratory Behaviors in the Offspring: A Mouse Model

http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0008456

Accumulating evidence from epidemiological research has demonstrated an association between advanced paternal age and risk for several psychiatric disorders including autism, schizophrenia and early-onset bipolar disorder. In order to establish causality, this study used an animal model to investigate the effects of advanced paternal age on behavioural deficits in the offspring.

C57BL/6J offspring (n = 12 per group) were bred from fathers of two different ages, 2 months (young) and 10 months (old), and mothers aged 2 months (n = 6 breeding pairs per group). Social and exploratory behaviors were examined in the offspring.

The offspring of older fathers were found to engage in significantly less social (p = 0.02) and exploratory (p = 0.02) behaviors than the offspring of younger fathers. There were no significant differences in measures of motor activity.

Given the well-controlled nature of this study, this provides the strongest evidence for deleterious effects of advancing paternal age on social and exploratory behavior. De-novo chromosomal changes and/or inherited epigenetic changes are the most plausible explanatory factors.


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Abstract
Introduction
Results
Discussion
Methods
Author Contributions
References
Rebecca G. Smith1#, Rachel L. Kember1#, Jonathan Mill1, Cathy Fernandes2*, Leonard C. Schalkwyk1, Joseph D. Buxbaum3,4, Abraham Reichenberg1,3

1 Medical Research Council Social Genetic and Developmental Psychiatry Centre, King's College London, London, United Kingdom, 2 Department of Psychological Medicine and Psychiatry, King's College London, London, United Kingdom, 3 Department of Psychiatry, Mount Sinai School of Medicine, New York, New York, United States of America, 4 Laboratory of Molecular Neuropsychiatry, and the Seaver Autism Center for Research and Treatment, Mount Sinai School of Medicine, New York, New York, United States of America

Abstract Top
Background
Accumulating evidence from epidemiological research has demonstrated an association between advanced paternal age and risk for several psychiatric disorders including autism, schizophrenia and early-onset bipolar disorder. In order to establish causality, this study used an animal model to investigate the effects of advanced paternal age on behavioural deficits in the offspring.

Methods
C57BL/6J offspring (n = 12 per group) were bred from fathers of two different ages, 2 months (young) and 10 months (old), and mothers aged 2 months (n = 6 breeding pairs per group). Social and exploratory behaviors were examined in the offspring.

Principal Findings
The offspring of older fathers were found to engage in significantly less social (p = 0.02) and exploratory (p = 0.02) behaviors than the offspring of younger fathers. There were no significant differences in measures of motor activity.

Conclusions
Given the well-controlled nature of this study, this provides the strongest evidence for deleterious effects of advancing paternal age on social and exploratory behavior. De-novo chromosomal changes and/or inherited epigenetic changes are the most plausible explanatory factors.

Citation: Smith RG, Kember RL, Mill J, Fernandes C, Schalkwyk LC, et al. (2009) Advancing Paternal Age Is Associated with Deficits in Social and Exploratory Behaviors in the Offspring: A Mouse Model. PLoS ONE 4(12): e8456. doi:10.1371/journal.pone.0008456

Editor: Kenji Hashimoto, Chiba University Center for Forensic Mental Health, Japan


Received: October 28, 2009; Accepted: December 2, 2009; Published: December 30, 2009

Copyright: © 2009 Smith et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: This study was supported by the Beatrice and Samuel A. Seaver Foundation, by a British Medical Association Margaret Temple Award, and National Institute of Health Research (NIHR) Biomedical Research Centre (BRC) for Mental Health at the South London and Maudsley National Health Service (NHS) Foundation Trust and Institute of Psychiatry, King's College London (KCL) Pilot Award to Drs. Jonathan Mill and Abraham (Avi) Reichenberg. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

* E-mail: cathy.fernandes@kcl.ac.uk

# These authors contributed equally to this work.

Introduction Top
Accumulating evidence from epidemiological research has demonstrated an association between advanced paternal age and risk for several psychiatric disorders including autism [1], schizophrenia [2] and early-onset bipolar disorder [3]. Despite the methodological advantages of epidemiological research, a major limitation is that techniques are limited to observation. In order to establish causality, experimental evidence in the form of randomized-controlled trials or the development of animal models is required [4]. Animal models are particularly important as they allow environmental and genetic confounds to be controlled.

The lack of complete specificity in the association between advancing paternal age and psychiatric disorders may suggest that advancing paternal age is related to phenotypes shared across disorders. One phenotype in-common to schizophrenia, autism and bipolar disorder is abnormalities in social cognition broadly defined severe social deficit [5], [6], [7], [8]. A recent epidemiological study found an association between advancing paternal age and impaired social functioning in male offspring in the general population [9].

In this study we examined the effect of older paternal age on social and non-social behavior in mice. To the best of our knowledge this is the first fully-controlled animal study of the effects of paternal age on these behaviors.

Results Top
Social Behavior
Offspring of old fathers engaged in less social activity than the offspring of young fathers, spending less time socially-interacting with the conspecific mice (t = 2.23, d.f. = 22, p = 0.02, one-tailed test, Figure 1). This result was consistently observed across all measures of social behavior. There were no significant differences in overall locomotor activity.

Figure 1. Results of social behavioral data from male offspring of young fathers (n = 12) and old fathers (n = 12).

* shows a p-value of less than 0.05, † shows p-value of 0.06. A. Mean time (±SEM) displaying all social behaviors toward a conspecific mouse (broken down into components in B, C and D). B. Mean time (±SEM) displaying allogrooming behavior towards a conspecific mouse. C. Mean time (±SEM) displaying anogenital sniffing behavior towards a conspecific mouse. D. Mean time (±SEM) displaying sniffing behavior towards a conspecific mouse.

doi:10.1371/journal.pone.0008456.g001
Exploration in the Holeboard
Offspring of old fathers demonstrated reduced exploration in the holeboard, making fewer nose pokes and spending less time nose poking than offspring of young fathers (t = −2.21, d.f. = 22, p = 0.02; Figure 2A). No significant differences were evident in distance moved or time spent in the centre of the Holeboard arena.

Figure 2. Results of holeboard and open field data from male offspring of young fathers (n = 12) and old fathers (n = 12).

* shows a p-value of less than 0.05. A. Mean number of nose pokes (±SEM) into holes in the holeboard trial. B. Mean time spent in each area of arena (±SEM) in the open field task.

doi:10.1371/journal.pone.0008456.g002
Exploration in the Open Field
Offspring of old fathers were less exploratory in the Open Field, taking longer to enter the central zone of the arena (t = 1.7837, d.f. = 22, p = 0.04). However, there were no significant differences inthe time spent in the middle (t = −0.9548, d.f. = 22, p = 0.1785) or central zones (t = −1.3166, d.f. = 22, p = 0.1056) (Figure 2B) or in overall locomotor activity between offspring of old fathers and offspring of young fathers in the open field.

To further explore these findings we examined the same set of behaviors in a small group of mice that were the offspring of very old fathers (aged >12 months, n = 9 male offspring generated from 7 breeding pairs). The behavioral results of reduced social behavior and exploration were seen in the offspring of very old fathers, but the numbers are too small to allow for a reliable statistical test (data not shown).

Discussion Top
Using a mouse model we documented deleterious effects of advancing paternal age on offspring behavior. Male offspring of older fathers engaged in less social behavior and exhibited less exploration in a novel environment. These effects were not confounded by differences in overall locomotor activity. Abnormalities in social behavior characterize psychiatric disorders previously linked to advancing paternal age, suggesting a common phenotype affected by paternal age.

There are several advantages for the mouse model used in this study. First, given the tractable nature of animal work, the environment was tightly controlled, minimizing any environmental confounds. Second, the age of all the mothers of the offspring was standard such that differences observed in the offspring cannot be accounted for by maternal age.

Finally, the most common reference inbred strain of mouse was used (C57BL/6J), reducing genetic variation.

In men, it is thought that the spermatogonial stem cell divisions occurring over the life-course of males result in higher mutational rates and cytogenetic abnormalities in the sperm of older men [10], [11]. Numerous neurological and psychiatric disorders have been related to genomic alterations [12]. A number of studies have uncovered an increased prevalence of de-novo copy-number variants (CNVs), and other forms of genomic alterations in autistic and in schizophrenia cases [13], [14].

An alternative explanation is that epigenetic dysfunction underlies some paternal age effects. Epigenetic dysfunction has been associated with several neuropsychiatric disorders, including schizophrenia and bipolar disorder [15]. A study by Flanagan and colleagues [16] reported intra- and inter-individual epigenetic variability in the male germline, and found a number of genes that demonstrated age-related DNA-methylation changes. Epigenetic signals are generally reprogrammed in the germline, although it appears that such reprogramming may not be fully complete across all regions of the genome [17]. In particular, repetitive and transposable elements in the genome, which are generally hypermethylated, are often not efficiently reprogrammed [18]. It is thus plausible that de novo structural mutations, which are often associated with repetitive DNA sequence motifs, may also be subjected to differential epigenetic reprogramming implicating both mutagenic and epigenetic processes in the phenotypic manifestation of increased paternal age.

Despite the advantages of this model, the results of this study should be interpreted in light of some limitations. We only examined one strain of male mice. This was a-priori decided in order to follow common practice in animal research aimed at limiting variation caused by sex differences in behaviors. Hence, findings should not be generalized across sexes. In addition, behavior was assessed at one developmental stage (12 weeks, young adulthood). Thus, the developmental nature of these differences could not be determined.

In conclusion, this study provides the strongest evidence to date for the behavioral effects of advancing paternal age on the offspring. Studies are ongoing to investigate the role of molecular changes in mediating the effects of advancing paternal age on social and exploratory behaviors in offspring, by assessing de-novo CNV events and alterations in DNA methylation.

Methods Top
Breeding Strategy
C57BL/6J mice were bred and maintained in the Biological Services Unit at the Institute of Psychiatry, Kings College London using stocks purchased from Charles River Laboratories. All housing and experimental procedures were performed in accordance with the UK Home Office Animals (Scientific Procedures) Act 1986. Typical breeding age for mice starts at 2 months. Male breeders are generally retired after 7–8 months. Therefore, females aged 2 months were bred with males of two different ages; young males of 2 months (n = 6 breeding pairs), and old males of 10 months (n = 6 breeding pairs). The average litter size within each age group was 7 (male to female ratio 1:1) and total progeny generated was 40 mice in the young fathers group and 44 mice in the old fathers group. Two males were randomly selected from each litter (n = 12 males per group) and weaned aged 4–5 weeks and pair housed with their siblings and then individually housed for two weeks prior to testing. Mice were housed in standard cages measuring 30.5×13×11 cm, with food and water available ad libitum. The housing room was maintained on a standard light/dark cycle with white lights on from 08:00 to 20:00. Ambient temperature in all rooms was maintained at 21±2°C with 45% humidity.

Offspring Behavioral Testing
Offspring were aged 12 weeks at the start of testing and all testing took place during the light phase with a light level <30 lux in the test room. Each apparatus was wiped clean with 1% Trigene® between subjects to avoid olfactory cueing behaviors. Behaviors for all tests were recorded on videotapes for further detailed analysis. Mice were returned to their home cage at the end of each test.

Social Behavior
The social behavior of the test mice towards a juvenile conspecific was assessed in a 5 minute trial [19]. The test mouse is habituated in an arena (36×20×14 cm) for 5 minutes, after which a male juvenile conspecific of the same strain (aged 4 weeks) was introduced for a further 5 minutes. During this trial, social behavior (including social sniffing, anogenital sniffing and allogrooming) by the test mouse towards the conspecific were scored from videotape by an observer blind to the group factor of paternal age.

Holeboard
The holeboard test is used to measure activity and exploration in a novel arena [20]. The Truscan Photo Beam Activity System (Coulbourn Instruments, Whitehall, PA) was used, which consists of an arena (25.4 cm square) and a nose poke floor with 16 holes (4×4 array) with sensor rings to track movement. The beams are spaced 1.52 cm apart providing a 0.76 cm spatial resolution. Animals were placed in the arena and the movement, the number of nose pokes and the time spent nose poking were recorded automatically by beam breaks for 5 minutes using the Truscan program.

Open Field
The open field [21] used a square white acrylic box with dimensions 72×72×33 cm. The animal was placed in the outer part of the arena facing an outer wall and allowed to freely explore the arena for 5 minutes. A video camera placed above the arena allowed movement to be tracked using an automated tracking system (Ethovision, Noldus Information Technologies). The number of faecal boli and urination were recorded at the end of the test. A square of equal distance from the periphery (36×36 cm) was defined in Ethovision as the ‘outer’, ‘middle’ and ‘central’ zones in order to determine the number of entries into, and time spent in, these zones in the arena. In addition, the latency to enter the inner zones as well as locomotor activity in all three zones of the arena were measured by the tracking system.

Statistical Analysis
Behavioral performances of offspring of young fathers and offspring of old fathers in the social interaction task, holeboard and open field were compared using unpaired, one-tailed Students t-tests. Significance level was set at 0.05.

Author Contributions Top
Conceived and designed the experiments: JM CF LCS AR. Performed the experiments: RGS RLK. Analyzed the data: RGS RLK CF. Contributed reagents/materials/analysis tools: JDB. Wrote the paper: RGS RLK JM CF LCS AR.

References Top
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Torrey EF, Buka S, Cannon TD, Goldstein JM, Seidman LJ, et al. (2009) Paternal age as a risk factor for schizophrenia: how important is it? Schizophr Res 114: 1–5. Find this article online
Frans EM, Sandin S, Reichenberg A, Lichtenstein P, Langstrom N, et al. (2008) Advancing paternal age and bipolar disorder. Arch Gen Psychiatry 65: 1034–1040. Find this article online
Rothman KJ, Greenland S (1997) Modern Epidemiology: Lippincott Williams and Wilkins.
Geschwind DH (2009) Advances in autism. Annu Rev Med 60: 367–380. Find this article online
Green MF, Penn DL, Bentall R, Carpenter WT, Gaebel W, et al. (2008) Social cognition in schizophrenia: an NIMH workshop on definitions, assessment, and research opportunities. Schizophr Bull 34: 1211–1220. Find this article online
Green MF (2006) Cognitive impairment and functional outcome in schizophrenia and bipolar disorder. J Clin Psychiatry 67: e12. Find this article online
Brotman MA, Skup M, Rich BA, Blair KS, Pine DS, et al. (2008) Risk for bipolar disorder is associated with face-processing deficits across emotions. J Am Acad Child Adolesc Psychiatry 47: 1455–1461. Find this article online
Weiser M, Reichenberg A, Werbeloff N, Kleinhaus K, Lubin G, et al. (2008) Advanced parental age at birth is associated with poorer social functioning in adolescent males: shedding light on a core symptom of schizophrenia and autism. Schizophr Bull 34: 1042–1046. Find this article online
Crow JF (2000) The origins, patterns and implications of human spontaneous mutation. Nat Rev Genet 1: 40–47. Find this article online
Buwe A, Guttenbach M, Schmid M (2005) Effect of paternal age on the frequency of cytogenetic abnormalities in human spermatozoa. Cytogenet Genome Res 111: 213–228. Find this article online
Reichenberg A, Mill J, MacCabe J (In Press) Epigenetics, Genomic Mutations and Cognitive Function. Cognitive Neuropsychitry. Find this article online
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"However, birth defects and genetic diseases have been associated with advanced paternal age, especially for fathers above the age of 50,"

Baby bonus


Sat, Dec 26, 2009
Mind Your Body, The Straits Times



Put 50 couples in a room and chances are that seven or eight of them have a fertility problem.

That is assuming they all want to start a family. In a society which reveres the family, however, childless couples have it tough. "For many couples, having a baby is often an easy, uncomplicated and joyous time. But the effects can be devastating for those experiencing infertility," said Dr Suresh Nair.

Related:
» Common causes of infertility(women)
» Common causes of infertility(men)
» Help to usher in the stork
» Happy Mum 1
» Happy Mum 2
The obstetrician, gynaecologist and medical director of Parkway Fertility Centre at Mount Elizabeth Hospital added: "It is a life crisis that can be extremely frustrating and depressing."


It affects a couple's hopes, dreams and future plans and can lead to shock, disbelief, anger, sadness, blame and even marital discord and loss of self-esteem, Dr Nair said.

Infertility is the inability to conceive after a couple has actively tried to do so over the past 12 months, said Dr Ann Tan, a consultant obstetrician and gynaecologist at Women and Fetal Centre.

A Ministry of Health spokesman said it is estimated that 15 per cent of couples here are affected by infertility. When a normal, healthy young couple have sexual intercourse, the chance of the woman getting pregnant is about 25 per cent.

After sex, sperm released by the male partner into the woman's vagina needs to travel up her fallopian tubes to fertilise the egg. When fertilisation occurs, an embryo is formed, which then moves down into the woman's womb or uterus for implantation.

Most fertile when young

Women reach peak fertility in their 20s. They are most fertile in the middle of their 28- to 30-day cycle.

Dr Stephen Chew, a senior consultant at the department of obstetrics and gynaecology at National University Hospital, said: "The woman's age is the most important factor determining fertility outcome."

Fertility in women falls by 4 to 8 per cent when they are between 25 and 29 years old; 15 to 19 per cent between 30 and 34 years old; 26 to 46 per cent between 35 and 39 years old; and 95 per cent by the time they hit 45 years of age.

Women stop producing eggs once they reach menopause and the average age when this occurs is 48 years. Natural spontaneous conception is not possible after menopause.

Age no barrier for men

In contrast, men are fertile from puberty until their 70s, although their testosterone levels decline at a rate of about 1 per cent each year after the age of 30.

Sperm quality, quantity and sexual performance also go downhill as men get older. Dr Jazlan Joosoph, a specialist in obstetrics & gynaecology at Raffles Hospital, said: "For men, the biological clock never stops. It only slows down.

"However, birth defects and genetic diseases have been associated with advanced paternal age, especially for fathers above the age of 50," Dr Jazlan said.

This is due to poorer sperm quality. "Men, like women, are advised to start procreation at an early age," he added.

Other health factors

Various other factors can cause infertility. In women, it can arise from one of three sites: the eggs, the fallopian tubes and the uterus. Dr Nair said: "Fallopian tube problems include endometriosis, pelvic inflammatory disease and ectopic pregnancies which damage the tubes.

"A woman may also suffer from a misshapen or scarred womb, one that is physically unable to either have the embryo take seed or to nurture the developing foetus."

Dr Jazlan added: "Ovulatory problems are common causes of female infertility. Successful fertilisation or conception cannot occur if there is absence of egg production or if there are eggs of poor quality."

In men, infertility can be due to defects in sperm quality, its quantity or a sexual dysfunction such as premature ejaculation. Dr Loh Seong Feei, the head and senior consultant at the department of reproductive medicine at KK Women's and Children's Hospital, said: "Many factors can cause the quality or quantity of sperm in the ejaculate to be low.

"Some common causes include genital tract infection and varicocele (widening of the veins along the cord that holds up a man's testicles).

"These factors can result in abnormally shaped sperm, which may not fertilise the egg, poor sperm motility such that sperm is unable to swim through the cervix to meet the egg, and low or zero sperm count."

Illnesses like mumps or cancer also affect fertility in men.

Lifestyle choices

Professor P.C. Wong, the head and senior consultant at the reproductive endocrinology and infertility division in the obstetrics and gynaecology department at National University Hospital, said smoking affects sperm production, causing sperm quality and quantity to drop.

Dr Nair said that sperm concentration and motility fall by 19 per cent and 29 per cent respectively in men who smoke 10 to 20 cigarettes a day.

Besides smoking, other lifestyle factors also play a part in fertility.

Heavy drinking, over-exercise, anorexia and obesity contribute to infertility in men and women.

Of course, infertility is never just one partner's problem.

Dr Nair said: "Knowing that you are less fertile and having to perform the sexual act can be demanding.

"This can affect spontaneity and lead to sexual difficulties or psychological stress that can strain the marriage or relationship."

junec@sph.com.sg

'Effect of advanced paternal age on fertility and pregnancy'

Medline ® Abstracts for References

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7
TI Changes with age in the level and duration of fertility in the menstrual cycle.
AU Dunson DB; Colombo B; Baird DD
SO Hum Reprod 2002 May;17(5):1399-403.

BACKGROUND: Most analyses of age-related changes in fertility cannot separate effects due to reduced frequency of sexual intercourse from effects directly related to ageing. Information on intercourse collected daily through each menstrual cycle provides the data for estimating day-specific probabilities of pregnancy for specific days relative to ovulation, and these estimates allow unconfounded analysis of ageing effects. METHODS: A total of 782 healthy couples using natural family planning methods contributed prospective data on 5860 menstrual cycles. Day of ovulation was based on basal body temperature measurements. Estimates of day-specific probabilities of pregnancy and the length of the fertile window were compared across age groups. RESULTS: Nearly all pregnancies occurred within a 6 day fertile window. There was no evidence for a shorter fertile window in older men or women. On average, the day-specific probabilities of pregnancy declined with age for women from the late 20s onward, with probabilities of pregnancy twice as high for women aged 19-26 years compared with women aged 35-39 years. Controlling for age of the woman, fertility was significantly reduced for men aged>35 years. CONCLUSIONS: Women's fertility begins to decline in the late 20s with substantial decreases by the late 30s. Fertility for men is less affected by age, but shows significant decline by the late 30s.

AD Biostatistics Branch, MD A3-03, National Institute of Environmental Health Sciences, National Institutes of Health, P.O.Box 12233, Research Triangle Park, NC 27709, USA. dunson1@niehs.nih.gov
PMID 11980771

--------------------------------------------------------------------------------

8
TI Effect of male age on fertility: evidence for the decline in male fertility with increasing age.
AU Hassan MA; Killick SR
SO Fertil Steril 2003 Jun;79 Suppl 3:1520-7.

OBJECTIVE: To evaluate the effect of men's age on time to pregnancy (TTP) using age at the onset of pregnancy attempts, adjusting for the confounding effects of women's age, coital frequency, and life-style characteristics. DESIGN: Observational study. SETTINGS: Teaching hospital in Hull, United Kingdom. PATIENT(S): Two thousand one hundred twelve consecutive pregnant women. INTERVENTION(S): A questionnaire inquiring about TTP, contraceptive use, pregnancy planning, previous subfertility, previous pregnancies, age, and individual life-style characteristics of both partners. MAIN OUTCOME MEASURE(S): Time to pregnancy, conception rates, and relative risk of subfecundity for men and women's age groups. RESULTS: As with women's age, increasing men's age was associated with significantly rising TTP and declining conception rates. A fivefold increase in TTP occurred with men's age>45 years. Relative to men<25 years old, those>45 years were 4.6-fold and 12.5-fold more likely to have had TTP of>1 or>2 years. Restricting the analysis to partners of young women revealed similar effects of increasing men's age. Women>35 years were 2.2-fold more likely to be subfertile than women<25 years. The results were comparable, whether age at conception or at the onset of pregnancy attempts was analyzed, and they remained unchanged after adjustment for the confounding factors. CONCLUSION(S): Evidence for and quantification of the decline in men's fertility with increasing age is provided.

AD The University of Hull, Post Graduate Medical Institute and Hull&York Medical School, Hull, United Kingdom. manhassan@yahoo.com
PMID 12801554

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9
TI The effect of advancing paternal age on pregnancy and live birth rates in couples undergoing in vitro fertilization or gamete intrafallopian transfer.
AU Klonoff-Cohen HS; Natarajan L
SO Am J Obstet Gynecol 2004 Aug;191(2):507-14.

OBJECTIVE: This study was undertaken to determine effects of male aging on sperm parameters, fertilization, pregnancy, and live birth rates among in vitro fertilization (IVF) or gamete intrafallopian transfer (GIFT) couples. The impact of female age was also investigated. STUDY DESIGN: Prospective study was made up of 221 IVF and GIFT couples. RESULTS: Pregnancy rates declined as the male subjects aged. Each additional year of paternal age was associated with 11% increased odds (P=.007) of not achieving a pregnancy, and 12% odds (P=.01) of not having a successful live birth. For first-time IVF/GIFT recipients, each additional year of paternal age was associated with a 5% increased odds of not achieving a pregnancy, whereas for repeaters it was 40% (P=.01). Advancing maternal age was associated with decreased numbers of oocytes retrieved or fertilized. Women 40 years or older compared with younger than 35 years had greater than 4-fold risk of not becoming pregnant, and greater than 20-fold risk of not achieving a live birth. CONCLUSION: Advancing paternal (and maternal) age had a deleterious effect on IVF and GIFT outcomes.

AD Department of Family and Preventive Medicine, University of California, San Diego, CA, USA.
PMID 15343228

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10
TI Paternal age>or=40 years: an important risk factor for infertility.
AU de La Rochebrochard E; Thonneau P
SO Am J Obstet Gynecol 2003 Oct;189(4):901-5.

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.

AD Institut National de la Sante et de la Recherche Medicale, Le Kremlin-Bicetre, France.
PMID 14586322

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11
TI Fathers over 40 and increased failure to conceive: the lessons of in vitro fertilization in France.
AU de La Rochebrochard E; de Mouzon J; Thepot F; Thonneau P
SO Fertil Steril. 2006 May;85(5):1420-4. Epub 2006 Apr 17.

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.

AD INED, Le Kremlin-Bicetre, F-94276, France. roche@ined.fr
PMID 16616749

The Male Biological Clock

Aging, Mitochondria and Male Reproductive Function.

Curr Aging Sci. 2009 Dec;2(3):165-173.

Aging, Mitochondria and Male Reproductive Function.
Amaral S, Ramalho-Santos J.

Center for Neuroscience and Cell Biology, Department of Zoology, School of Science and Technology, University of Coimbra, 3004-517 Coimbra, Portugal. jramalho@ci.uc.pt.

The rise in life expectancy over the last century, together with higher maternal and paternal ages and have highlighted the issue of reduced fertility with advancing age. Aging of the male reproductive system is incited by multi-factorial changes at molecular, cellular and regulatory levels, and individual characteristics are highly variable, although strongly influenced by lifestyle and environmental factors. Damage accumulated with age leads to progressive deregulation of the hypothalamic-pituitary-gonadal axis and of local auto/paracrine interactions, thereby inducing changes in target organs such as the testis, penis and prostate. Elderly human males produce less testosterone, have fewer motile sperm and a higher incidence of erectile dysfunction and prostate disorders, all of which contribute to lower fertility. Cellular aging can manifest itself at several levels. Aging cells progressively accumulate "waste" products, resulting in a decreased functionally. Changes to mitochondria are among the most remarkable features observed in aging cells and several theories place mitochondria at the hub of cellular events related to aging, namely in terms of the accumulation of oxidative damage to cells and tissues, a process in which these organelles may play a prominent role, although alternative theories have also emerged. Furthermore, mitochondrial energy metabolism is also crucial for male reproductive function and mitochondria may therefore constitute a common link between aging and fertility loss.

Man’s Age Affects Pregnancy Success And Miscarriage Rate In Couples With Fertility Problems

Man’s Age Affects Pregnancy Success And Miscarriage Rate In Couples With Fertility Problems
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Researchers in France studying over 12,000 couples with fertility problems found that when the man was over 35 pregnancy rates fell and
perhaps more surprisingly, miscarriage rates rose, leading them to conclude that the age of the father was just as important as the age of the mother
in reaching a successful pregnancy.

The findings are being presented today, Monday 7th July, at the 24th annual conference of the European Society of Human Reproduction and
Embryology (ESHRE) in Barcelona, Spain, by lead investigator Dr Stephanie Belloc, of the Eylau Centre for Assisted Reproduction in Paris,
France.

This is the first time such a strong effect from the father on reproductive success rates has been found from research, said Belloc in a press
statement.

Belloc and her team studied 12,236 couples who underwent 21,239 intrauterine inseminations (IUIs) at the Eylau Centre between January 2002 and
December 2006 and used the male partner’s sperm (as opposed to donated sperm) in all cases. Most couples were being treated because of the
man’s infertility.

In IUI, the sperm is spun in a centrifuge to remove the seminal fluid and then inserted directly into the uterus while the woman is ovulating. This
technique is less invasive than IVF and is used when the woman’s fertility is not a problem.

If the sperm is not “washed” in the centrifuge to remove the seminal fluid, the prostaglandins in the seminal fluid can cause cramps in the uterus which
expels the semen.

For each IUI, the sperm was examined for a number of characteristics, such as sperm count, motility (how agile they are) and morphology or shape,
and the clinical pregnancy, miscarriage and delivery rates were noted. The researchers then analyzed the results, distinguishing between male and
female factors in influencing outcomes for each IUI case.

The results showed that maternal age was closely linked to decreased pregnancy rate, which was 8.9 per cent in women over 35 compared to 14.5
per cent in younger women.

But the scientists also found that the father’s age was also important, not only on pregnancy rates, but perhaps more surprisingly, on the rate of
miscarriage, with a pronounced negative effect once the father was over 35 years of age.

The effect of the mother’s age on conception and miscarriage rates is already well known to scientists, but the effect of the father has not been very
clear; studies have shown that sperm count and quality declines as men get older, but until now there has been no clinical evidence of the impact of
the age of the man on a couple’s ability to have a successful pregnancy.

As Belloc explained, it was a question that needed to be answered once and for all:

“We already believed that couples where the man was older took longer to conceive, but a number of reasons had been put forward for
this.”

“Neither was there any definite evidence that miscarriage rates increased when the man was older,” she said.

Speculating on the reasons why the age of the man should impact fertility, Belloc said a number of recent studies have shown a ink between IUI
success and DNA damage, which is linked to the man’s age.

The researchers are hoping to gather more evidence as they add more couples to the study in the coming years.

Belloc said this research will yield important information for couples wanting to start a family, and the larger the pool of couples from which the
evidence is drawn the more helpful the information will be.

The study is clinical evidence to support the notion that DNA damage in older men reflects in fertility, Belloc said:

“Our research proves for the first time that there is a strong paternal age-related effect on IUI outcomes, and this information should be considered
by both doctors and patients in assisted reproduction programmes.”

She said that perhaps this will support the recommendation that IVF or ICSI should be the preferred treatment when either of the partners is over 35.
In IVF the outer membrane of the egg (the zona pellucida) appears to stop the entry of sperm with DNA damage, and in ICSI, the best quality sperm
is selected out.

“These methods, although not in themselves a guarantee of success, may help couples where the man is older to achieve a pregnancy more quickly,
and also reduce the risk of miscarriage,” said Belloc.

A representative of the Eylau Centre also said on an interview with the BBC aired early this morning that the likely cause of the decrease in male
fertility after 35 was DNA fragmentation. He said that DNA fragmentation was not unusual in male sperm and often this is repaired “by the woman”,
but when it is too fragmented it is beyond repair, leading to pregnancy failure and miscarriage, he said.

Egg and sperm donation rules to be reviewed

Egg and sperm donation rules to be reviewed

By John von Radowitz, Press Association


Wednesday, 9 December 2009



A major review of the rules regarding sperm, egg and embryo donation will take place over the course of next year.


The most controversial area to be discussed concerns expenses payments made to donors.


Also on the agenda will be age limits for male and female donors, and restrictions on how many families a man can donate his sperm to.


Currently in the UK payments for sperm and egg donations can only be made to reimburse travel costs and loss of earnings.


Some other European countries interpret the rules more liberally to include compensation for "inconvenience".


Under EU law donors cannot be paid directly for their eggs and sperm, as happens in the US where people earn large sums of money helping infertile couples. An EU directive limits compensation to "making good expenses and inconveniences related to the donation".


In the UK expenses payments for donors are broadly in line with those given to jurors. There is an overall limit of £250 for each course of sperm or egg donation.


Four years ago the Human Fertilisation and Embryology Authority (HFEA), which regulates fertility services and research, decided not to allow compensation for "inconvenience". It was felt that paying "inconvenience" money might encourage people to make donations without thinking enough of the consequences.


Since then there have been calls for more flexibility to better reflect the sacrifices made by many donors.


Members of the HFEA agreed to hold the review at a meeting today.


Professor Lisa Jardine, who chairs the authority, said: "The authority had a rewarding and well informed debate across a wide range of important issues and arrived at some significant decisions. I welcome the fact that we are now beyond the implementation of the new legislation and can address issues which have implications for all of our stakeholders.


"There was a general view that the HFEA's policy with regard to reimbursement for donors, which has now been in place for two years since the introduction of the European Tissue and Cell Directive, was one that could usefully be revisited in light of what we have learned over those two years. We will not prejudge the outcome of the review that will now take place."


Other issues to be addressed include whether to change the current lower age limit for egg donation, which currently stands at 18, to take account of potential health risks.


The authority will also look at whether its upper age limit of sperm donors should be brought in line with professional guidelines. The official age limit is now 45, while the professional guidance recommends 40 or younger.


Also under discussion is the 10-family limit for sperm donors. This prevents a man donating his sperm to more than 10 families, irrespective of the number of babies that result.


Egg sharing, donations between family members, and the possibility of allowing people only to donate to certain patient groups will also be considered.

Man's age has a direct effect on fertility

Man's age has a direct effect on fertility: reportMatthew CouttsThe age of the potential father - not just the mother - can seriously limit the chances of having a baby later in life, according to a study released today.

While it has long been documented would-be mothers in their mid-30s or older face reduced pregnancy rates and increased miscarriages, researchers say this is the strongest proof to date that similar problems are caused by the age of the would-be father in couples that face difficulty conceiving.

Researchers at France's Eylau Centre for Assisted Reproduction monitored 21, 239 cases of intrauterine inseminations (IUI), an effective type of artificial insemination, in more than 12,000 couples between 2002 and 2006.

They found maternal age was closely associated with a decrease in the pregnancy rate - 8.9 per cent in women over 35 years, compared with 14.5 per cent in younger women - as well as a higher miscarriage rate.

"But we also demonstrated that the age of the father was important in the rate of pregnancy, with a negative effect for men over 40,'' said Stephanie Belloc, lead author of the study.

"And even more surprising, the proportion of miscarriages went up as well, '' she added.

The study, to be presented at the European Society of Human Reproduction and Embryology conference in Barcelona, showed paternal age led to decreases in the pregnancy rate, from 12.3 per cent with fathers 30 years of age or younger, to 9.3 per cent in fathers older than 45 years of age. The rate of miscarriage more than doubled over the same periods, from 13.7 per cent to 32.4 per cent.

In most cases the couples were being treated at the clinic because the husband had infertility issues, but researchers say the findings relate to men without such problems. "There is no doubt that we can extrapolate from the study to men in general,'' said co-author Yves Menezo, also a researcher at the Eylau Centre.

In IUI the sperm is "washed'' in order to separate them from the seminal fluid, and then inserted directly into the uterus. The goal is to increase the chances of fertilization and remove any chemicals in the semen that may cause discomfort for the woman.

Belloc said sperm with DNA damage, common in older men, was still able to enter the egg during IUI, but the weakened sperm could result in failure to conceive. While previous reports show a decline in sperm count and quality in older men, this is the first clinical proof that a man's age has a direct effect on fertility.

National Post, with files from AFP