Sexual activity, fertility and contraceptive use in middle-aged and older men: Men in Australia, Telephone Survey (MATeS)

Male or female sterilization - the decision making process: Counselling and regret

OBJECTIVE(S)

To analyze the decision-making process of both male and female sterilization in order to improve counselling and prevent regret after sterilization in the future.

STUDY DESIGN

An online questionnaire regarding sterilization (counselling, sources of information and regret) was promoted on Facebook, Twitter and LinkedIn. A total of 1107 men and women who had undergone or considered sterilization in the Netherlands filled in the questionnaire.

RESULTS

A total of 88.9 % of the sterilized group and 67.4 % in the considered group responded that they felt well informed when they considered sterilization. However, less than half of the participants in both groups knew about all different sterilization methods. In both groups participants reported they consulted their partner the most when they considered sterilization. After sterilization 7.7 % reported having regret. Regret was reported more often when participants were sterilized ≤ 30 years. Most important reasons for regret reported by males were complications, pain, a new wish to conceive and divorce/remarriage. Most important reasons for regret reported by females were pain, complications, a new wish to conceive and menstrual symptoms. A total of 21.1 % in the sterilized and 38.0 % in the considered group responded they would have liked to use a decision aid when they considered sterilization.

CONCLUSIONS

Findings of this study provide insight in the decision-making process regarding sterilization. There is a lack of knowledge of different methods of sterilization and 7.7% regrets their sterilization afterwards. Furthermore, the results show an importance of developing a decision aid for couples considering sterilization.

FSFI score and timing of tubal ligation in patients: preliminary results of an online survey

Introduction

Tubal ligation is the most common contraceptive method worldwide. Apart from a very low pearl index and anxiety relief, other benefits are not commonly recognised. In young patients, there is the post-operative risk of regretting the decision with the need for In-Vitro-Fertilisation or refertilising surgery. Positive side effects have not been widely published. In our study we investigated the change in the female sexual function index score after tubal ligation.

Material and method

In this survey the FSFI score of participants around the time of the tubal ligation was compared with the FSFI score of intermediate and long-term time distance to the ligation.

Results

The data indicate an increase in younger women seeking information on permanent contraception and whilst the FSFI score of the early group indicates a risk of female sexual dysfunction, the intermediate and long-term FSFI scores are comparable to published control groups.

Discussion

Besides the obvious benefit of a low pearl index, tubal ligation may contribute to reduce the risk of female sexual dysfunction in the mid and long term. Informed consent is essential for the surgeon and patient to weigh up the risks and benefits individually including possible future perspectives on family planning.

Relationship between socio-economic characteristics of older adults' women and family planning use in Botswana

Older adults (50 years and over) are still sexually active and therefore vulnerable to unplanned pregnancy, infection of STIs and HIV, yet there are no programmes in place to cater for their family planning needs. The objective of the study is to show how some socio-economic characteristics of older adults influence their family planning (FP) use. The study used a stratified random sampling design where four health districts (two urban and two rural) were purposively selected and the sample size of 444 older adult women allocated to the districts using proportional allocation to size. Snowball technique was used in identifying respondents. The multinomial logistic regression analysis reveals that while age, marital status, educational qualification, employment status, menopausal status, district and desire for another child jointly significantly predict FP use, only menopausal status and desire for another child individually significantly (p < 0.01) predict FP use. Older adult women who desired another child were significantly (p < 0.01) 7.5 times more likely to use family planning (FP) methods than those who do not want another child. The postmenopausal older adult women were less likely to use FP methods than those in their premenopausal state (OR = 0.13). Women with no schooling were less likely to use FP methods than those with degree/professional qualifications. Single and married women were less likely to use FP methods than the divorced/widowed/separated. The study recommends the promotion of education and training on FP use among the older adult women that will take into consideration their menopausal status and desire for another child. The training should be home-based.

Age differences in attitudes toward safer sex practices in heterosexual men using an Australian Internet dating service

Background This cross-sectional study investigated sexually transmissible infection (STI) knowledge, safer sex attitudes and behaviours of sexually active, heterosexual men using an Internet dating service, and explored factors associated with protective attitudes.

METHODS

An anonymous online survey was sent to men who had logged onto an Internet dating service within the previous year. Factors associated with discussing STIs before sex and condom use intention with a new partner were analysed.

RESULTS

In total, 2339 responses were analysed. Men had lower STI knowledge scores, lower use of condoms and greater beliefs that condoms reduced interest in sex as age increased. Younger men (aged 18-29 years) were more likely to report intentions of only having sex with a new partner if a condom was used compared with older men aged over 60 years. Predictors of having a discussion about STIs with a new partner were older age, better knowledge of STIs, greater distress at a potential diagnosis of an STI and stronger future condom use intention. Intention to only have sex with a new female partner if a condom was used was associated with higher STI knowledge, discussing STIs with a new partner and distress at a diagnosis of an STI. Men with a higher number of sexual partners in the last year were less likely to have an STI discussion with new partners or intend to use a condom with a new partner.

CONCLUSIONS

Older Internet-dating, heterosexual men are vulnerable to STIs. Health promotion interventions to increase STI awareness, condom use and STI testing in older men are warranted.

Contraception - what about the men? Experience, knowledge and attitudes: a survey of 2438 heterosexual men using an online dating service

Background There is little research on men's contraceptive knowledge, attitudes and beliefs, yet the male partner is known to influence contraceptive choices. This study investigates contraceptive experiences, knowledge, attitudes and beliefs of a sample of sexually active, heterosexual men via an online dating site.

METHODS

An anonymous online survey was sent to men who had logged onto an online dating site within the previous year.

RESULTS

We analysed 2438 survey responses. A contraceptive method was used at last intercourse for 82% of men <50 years old versus 69% of men ≥50 (P<0.0001). Condoms (35%), vasectomy (22%) and the contraceptive pill (21%) were the most commonly used methods. Older men were less likely to use condoms than younger men (P<0.0001). More than 80% of participants had heard of each method. The greatest perceived harm was with the emergency contraceptive pill, with 32% responding that it was 'harmful to the health of the user' and 37% not sure. Belief that contraception decision-making should be shared between partners increased from 57% in a 'one-night stand' to 75% in a casual relationship, to 92% in a long-term relationship.

CONCLUSION

Among this sample there is high contraceptive use, especially vasectomy in older men and a desire to share contraceptive decision-making with their partners, especially in long-term relationships. However, low awareness of some methods and misperceptions about hormonal contraceptive method safety, especially the emergency contraceptive pill, highlight the need for education for men.

Can the evolution of male contraception lead to a revolution? Review of the current state of knowledge

Introduction

Great advances in medical research concerning methods of contraception have been achieved in recent years, however, more than 25% of couples worldwide still rely on condoms - a method with poor efficacy. Even though there is a spectrum of 11 different contraceptive methods for women, there are only 4 commonly used by men (condoms, periodic abstinence, withdrawal and vasectomy). In this review, advances and present, state-of-the-art, both hormonal and non-hormonal male contraceptive methods will be presented and evaluated. Potential novel targets that warrant greater research will be highlighted.

Material and methods

A comprehensive literature search without a time limit was performed using the Medline database on May 2017. The terms 'male contraception' in conjunction with 'reversible inhibition of sperm under guidance' (RISUG), 'hormonal', 'non-hormonal', 'vasectomy' or 'testosterone' were used. The articles were limited to those published in English, Polish or French.

Results

There are various contraceptives currently available to regulate male fertility. Vasectomy is still the most effective permanent form of male contraceptive with a failure rate lower than 1%. Reversible, non hormonal methods of male contraception, like reversible inhibition of sperm under guidance, are very promising and close to being introduced into the market. In regards to hormonal contraception research, the use of testosterone injections has been widely studied yet they often harbor undesirable side effects and require further development.

Conclusions

Despite continuous efforts worldwide, it seems that another several years of research is needed to provide safe, effective and affordable male contraceptives which will allow both men and women to participate fully in family planning.

Men's knowledge, attitudes and behaviours relating to fertility

BACKGROUND

The increasingly common practice in high-income countries to delay childbearing to the fourth and fifth decades of life increases the risk of involuntary childlessness or having fewer children than desired. Older age also increases the risk of age-related infertility, the need for ART to conceive, and obstetric and neonatal complications. Existing research relating to childbearing focusses almost exclusively on women, and in public discourse declining fertility rates are often assumed to be the result of women delaying childbearing to pursue other life goals such as a career and travel. However, evidence suggests that the lack of a partner or a partner willing to commit to parenthood is the main reason for later childbearing.

OBJECTIVE AND RATIONALE

To better understand men's contributions to childbearing decisions and outcomes, the literature pertaining to men's fertility-related knowledge, attitudes and behaviours was reviewed.

SEARCH METHODS

The electronic databases of Medline, Embase and PsycINFO were searched to identify investigations of men's knowledge, attitudes and behaviours relating to fertility, infertility, reproductive health or childbearing using relevant fertility keyword search terms. Studies were included if they had investigated factors associated with men's fertility-related knowledge, attitudes and behaviours, had been conducted in a high-income country and were published in an English language peer-reviewed journal between January 2005 and August 2016.

OUTCOMES

The search yielded 1349 citations. Of these, 47 papers representing 43 unique studies were included in the review. Where response rate was reported, it ranged between 13 and 94%. Studies varied in terms of research design; inclusion and exclusion criteria; recruitment strategies; adequacy of sample size; recruitment and retention rates and data collection tools. However, findings were consistent and indicate that men almost universally value parenthood, want and expect to become fathers, and aspire to have at least two children. Yet most men have inadequate knowledge about the limitations of female and male fertility and overestimate the chance of spontaneous and assisted conception. Perceptions of ideal circumstances in which to have children included being in a stable and loving relationship, having completed studies, secured a permanent job and a dependable income, having achieved personal maturity, and having a partner who desires children and is 'suitable' as a potential co-parent. Although all studies were conducted in high-income countries, between-country social and cultural differences may have influenced the findings relating to attitudes.

WIDER IMPLICATIONS

Men aspire to parenthood as much as women do but have limited knowledge about the factors that influence fertility. The gap between ideal biological and ideal social age for having children appears to be widening, narrowing the time frame in which parenthood can be achieved. This may lead to unfulfilled parenthood aspirations. The findings can inform government policies and public education strategies aimed to support childbearing during the most fertile years, reduce the personal and societal cost of infertility and ART use, and allow people to fulfil their parenthood goals.

Sex and the older man

Sexual health is an important part of an individual's physical and emotional wellbeing. Sexuality and sexual wellbeing are often associated with young people and therefore the needs of the older person can be overlooked. Such discrimination is unjustifiable given that statistics show a rise in sexually transmitted infections (STIs) and new diagnoses of HIV in the older man. These worrying trends emphasise the legitimate need for nurses to address sexuality and sexual wellbeing as an essential component of health care.

Sexual health discussions with older adult patients during periodic health exams

INTRODUCTION

Sexual health is an integral part of overall health across the lifespan. In order to address sexual health issues, such as sexually transmitted infections (STIs) and sexual functioning, the sexual history of adult patients should be incorporated as a routine part of the medical history throughout life. Physicians and health-care professionals cite many barriers to attending to and assessing the sexual health needs of older adult patients, underscoring the importance of additional research to improve sexual history taking among older patients.

AIM

The purpose of this article is to explore the content and context of physician-patient sexual health discussions during periodic health exams (PHEs) with adults aged 50-80 years.

METHODS

Patients completed a pre-visit telephone survey and attended a scheduled PHE with their permission to audio-record the exam. Transcribed audio recordings of 483 PHEs were analyzed according to the principles of qualitative content analysis.

MAIN OUTCOME MEASURES

Frequency of sexual history taking components as observed in transcripts of PHEs. Physician characteristics were obtained from health system records and patient characteristics were obtained from the pre-visit survey.

RESULTS

Analyses revealed that approximately one-half of the PHEs included some discussion about sexual health, with the majority of those conversations initiated by physicians. A two-level logistic regression model revealed that patient-physician gender concordance, race discordance, and increasing physician age were significantly associated with sexual health discussions.

CONCLUSION

Interventions should focus on increasing physician self-efficacy for assessing sexual health in gender discordant and race/ethnicity concordant patient interactions. Interventions for older adults should increase education about sexual health and sexual risk behaviors, as well as empower individuals to seek information from their health-care providers.

Healthy aging in a cross-sectional study of Australian men: what has sex got to do with it?

AIM

To identify lifestyle factors associated with healthy aging in middle-aged and older Australian men.

METHODS

A cross-sectional, population-based, computer-assisted telephone interview study explored self-reported health outcomes, and associated determinants for general and reproductive health (the Men in Australia Telephone Survey) in men aged 40 years and older (n = 5990). "Good health" was defined by self-reported health (excellent/very good) combined with absence of self-reported high blood pressure, heart disease, stroke, diabetes and depression symptoms. Categories of sexual activity frequency in the previous four weeks ranged from zero to 12+ times.

RESULTS

"Good health" declined with increasing age with 17% of men over 70 years reporting "good health". In multivariable logistic regression models, significant inverse associations were found between modifiable lifestyle factors - both underweight and overweight/obesity, physical inactivity, smoking and high alcohol consumption - and "good health". Low-risk alcohol intake and living with a partner were positively associated with "good health". Sexual activity was also positively associated with "good health" (p < 0.001) with elevated odds ratios (ORs) for each category of frequency of sexual activity (1-4, 5-8, 9-12 or 12+ times in the past 4 weeks) relative to zero frequency (ORs 1.68 to 2.16).

CONCLUSION

This study suggests that sexual activity is an important correlate of retaining good health in middle- and older-aged men, independent of other behavioral determinants.

Sexuality, health care and the older person: an overview of the literature

Abstract.  This paper reviews recent literature around sexuality, health care and the older person. The construction of sexuality and the importance of sexuality to older people are discussed, as is sexual diversity in old age, and sexuality and health. Also discussed are the myths and stereotypes associated with this topic, and the medical, social, healthcare, and institutional barriers to sexuality and sexual health in later life.

Barriers to the expression of sexuality in the older person: the role of the health professional

Sexuality is an important contributing factor to quality of life and sense of well-being. All adults have the right to express their sexuality, regardless of their age. Research indicates, however, that older people frequently experience barriers to the expression of their sexuality. Many of these barriers are influenced by the health professionals and services that care for them. This paper will outline these barriers and identify strategies that the healthcare professional can implement to help improve practice in this area.

‘It's kind of me taking responsibility for these things’: Men, vasectomy and ‘contraceptive economies’

This article examines vasectomy as a gendered practice of (non)reproductive masculinity. Reporting on interview-based data, in which a number of New Zealand men made sense of the operation, this article used critical thematic analysis to extract themes from semi-structured interviews with participants who had vasectomies in ‘typical’ circumstances. Primary themes of ‘taking responsibility’ and ‘vasectomy as an act of minor heroism’ were extracted from the data. We will argue that men constructed their ‘new found’ responsibility (and the heroic slant they added to it) within an ‘economy of gratitude’, meaning any involvement by men in the reproductive/contraceptive sphere is worthy of particular praise and value. While there may be some strategic value in these ideas, they draw upon existing discourses of orthodox masculinities and in this way may perpetuate (rather than challenge) the notion that men are doing something ‘special’ by having a vasectomy. This ‘specialness’ has the potential to ratify ongoing male privilege within heterosexual relationships, rather than the disruption that (at face value) it appears to be generating.

Sooner or later? Young Australian men's perspectives on timing of parenthood

Postponed parenthood has been identified as a significant driver of the trends towards smaller families and underachieved fertility aspirations. Understanding men's preferred timing and circumstances for fatherhood is needed to complement existing research among young women and increase understanding of postponed parenthood. We collected quantitative and qualitative data on attitudes regarding the timing of parenthood from 382 young Australian men attending university. Participants valued having a stable relationship and personal maturity before having children, with completed studies, financial security and a permanent yet flexible job also important. Programmes and policies which facilitate the establishment of important 'preconditions' for parenthood would support individuals to achieve their reproductive aspirations.

Are sexual problems more common in women who have had a tubal ligation? A population-based study of Australian women

OBJECTIVE

To investigate whether women who have had a tubal ligation are more likely to experience sexual problems than other women.

DESIGN

Population-based telephone survey.

SETTING

Australia-wide, including cities, regional towns, and rural areas.

POPULATION

A total of 3448 Australian women aged between 16 and 64 years.

METHODS

Women were surveyed using random-digit dialling throughout 2004 and 2005.

MAIN OUTCOME MEASURES

Prevalence of sexual problems and ratings of sexual satisfaction, relationship satisfaction, and sexual pleasure.

RESULTS

From a weighted sample of 2721 women, 447 (16.4%) reported having had a tubal ligation, with 85.0% currently aged between 40 and 64 years. Having a tubal ligation was not associated with any specific sexual problem, such as physical pain during sex or an inability to reach orgasm. In fact, after controlling for age and other sociodemographic differences, sterilised women were significantly less likely than non-sterilised women to lack an interest in having sex (OR 0.69, 95% CI 0.54-0.89), to take 'too long' to reach orgasm (OR 0.69, 95% CI 0.50-0.96), to experience vaginal dryness during sex (OR 0.70, 95% CI 0.50-0.96), and to find sex unpleasurable (OR 0.64, 95% CI 0.46-0.90). Sterilised women were also more likely to experience extremely high levels of sexual satisfaction (OR 1.66, 95% CI 1.27-2.18), relationship satisfaction (OR 1.29, 95% CI 1.01-1.67), and sexual pleasure (OR 1.59, 95% CI 1.20-2.12).

CONCLUSIONS

Our findings suggest no adverse effects, and possibly some benefits, for the sexual lives of women undergoing tubal ligation. These findings should be included with other educational material for couples considering sterilisation as a contraception option.

Are sexual problems more common in men who have had a vasectomy? A population-based study of Australian men

INTRODUCTION

It is not known whether sexual problems are currently more prevalent among men who have had a vasectomy compared with those who have not had a vasectomy.

AIM

To investigate whether vasectomized men are more likely to report experiencing a range of sexual problems than nonvasectomized men and to assess their overall sexual and relationship satisfaction.

METHODS

A population-based survey of 3,390 Australian men's sexual experiences was conducted using computer-assisted telephone interviewing.

MAIN OUTCOME MEASURES

Proportions of vasectomized and nonvasectomized men who: (i) reported a sexual problem for at least 1 month during the last 12 months; and (ii) rated their sexual and relationship satisfaction as either extremely satisfying or not extremely satisfying.

RESULTS

Vasectomy was reported by 25.1% of men, almost 70% of whom were aged 40-59 years. Vasectomized men were more likely to be married, live in regional areas, and speak English at home. Having a vasectomy was not associated with any specific sexual problem, such as lacking interest in sex or taking too long to reach orgasm. Vasectomized men (10.8%) were slightly more likely than nonvasectomized men (8.2%) to report problems maintaining an erection, but this difference disappeared when age and other socio-demographic variations were taken into account. Although vasectomized men (33.7%) were just as likely as nonvasectomized men (33.0%) to be extremely satisfied sexually, they were significantly more likely to be extremely satisfied with their relationship overall (48.3% vs. 42.9%).

CONCLUSION

Our findings suggest that sexual problems are no more prevalent among vasectomized men than they are among nonvasectomized men.

Male contraception: A realistic option?

This review illustrates the principle of hormonal male contraception and gives an overview of current trials aiming at the development of a marketable hormonal contraceptive for men. The principle of male hormonal contraception is based on strong suppression of gonadotropins in order to arrest spermatogenesis at the spermatogonial stem cell level, thus leading to azoospermia or severe oligozoospermia. Until now, it has not been possible to interrupt spermatogenesis effectively without simultaneously inhibiting the production of androgens by Leydig cells, resulting in a deficiency of extra-testicular androgens. Therefore, testosterone needs to be replaced. By administering exogenous testosterone alone azoospermia can be reached in East Asians, whereas azoospermia is only achieved in two-thirds of Caucasian volunteers so that in these men an additional agent is required. Currently injectable testosterone combined with gestagens or administered as implants are being tested for possible licensing. Although scrotal and non-scrotal testosterone patches, orally administered testosterone undecanoate and testosterone gels are generally well tolerated and provide stable testosterone levels in the normal range, their use showed generally disappointing efficacy due to insufficient gonadotropin suppression. Further large multi-centre studies are required to establish the contraceptive efficacy of the most promising steroid combinations.

A typology of men's sexual attitudes, erectile dysfunction treatment expectations and barriers

In total, 1122 men completed non-validated structured interviews on sexual attitudes and on erectile dysfunction treatment expectations and barriers. Dimensions of sexual attitudes and treatment expectations and barriers were extracted by factor analysis and subjects were grouped into types by cluster analysis. Five types emerged: the sensation seeker, the sensuous, the anxious, the confident and the abstinent. The majority of men agreed on the importance of sex for the partnership. For the majority of anxious, sensuous and sensation-seeking men, sex was important for self-esteem. Expecting quality of life, enjoyment, self-esteem and hard reliable erections from treatment with phosphodiesterase-5 inhibitors, anxieties for side effects and loss of control, sexual abstinence and desire for an intensive sex life had the strongest impact on the likelihood of use. Men's sexual attitudes vary considerably and impact reactions to erection difficulties. A typology of five groups was developed, which will contribute to research on and understanding of men's sexual and treatment-seeking behaviors.

[Ca2+]i signalling in sperm — making the most of what you've got

Thanks to a worrying decrease in male fertility, understanding how sperm 'work' is a matter both of interest and great importance. Sperm of all animals detect various environmental cues. The 'behavioural' and physiological responses of sperm must be specific, appropriate and correctly timed. Strangely, in a cell with few organelles and minimal cytoplasmic volume, internal Ca(2+) concentration, [Ca(2+)](i), regulates almost all these activities. How does such a simple cell achieve this - and is it as simple as it seems?

Men in Australia Telephone Survey (MATeS): predictors of men's help-seeking behaviour for reproductive health disorders

OBJECTIVE

To identify sociodemographic factors associated with help-seeking behaviour for reproductive health disorders in middle-aged and older Australian men.

DESIGN

A cross-sectional, population-based, computer-assisted telephone interview exploring sociodemographic factors and general and reproductive health.

PARTICIPANTS AND SETTING

Analysis of data from the Men in Australia Telephone Survey (MATeS) of 5990 Australian men aged 40 years and older interviewed between September and December 2003.

MAIN OUTCOME MEASURES

Self-reported diagnosis of prostate disease and erectile dysfunction (ED), help-seeking behaviour (including visiting a doctor, prostate-specific antigen testing, treatment of prostate disease, speaking to a health professional about ED and treatment of ED).

RESULTS

Age was a significant predictor of all help-seeking behaviour studied, other than treatment for ED. Controlling for all predictor variables, never-married status predicted a lower likelihood of visiting a doctor (odds ratio [OR], 0.68 [95% CI, 0.48-0.97]) or speaking to a health professional about ED (OR, 0.44 [95% CI, 0.21-0.93]), while divorced/separated status predicted lower likelihood of having a prostate-specific antigen test (OR, 0.63 [95% CI, 0.50-0.79]). Living in a regional or remote area or being from a non-English-speaking background predicted lower likelihood of receiving treatment for ED (ORs, 0.62 [95% CI, 0.42-0.92] and 0.41 [95% CI, 0.24-0.72], respectively), but did not influence screening for prostate disease.

CONCLUSION

Seeking advice or treatment for male reproductive health disorders is predicted by sociodemographic factors specific to different reproductive health problems. As middle-aged and older men do attend doctors, opportunities exist for health professionals to optimise their consultations by routinely discussing reproductive health with all men, to identify under-reported male reproductive health disorders.

Assessment of needs of men for decision support on male sterilization

OBJECTIVE

To assess the needs of men for decision support on male sterilization.

METHODS

Forty-two men facing a decision about undergoing a vasectomy or not and 11 physicians who perform vasectomy were interviewed to assess the sources of difficulty in this decision-making process. On the day of their vasectomy, 209 men completed the decisional conflict scale (DCS) and a knowledge test.

RESULTS

Sources of difficulty about the decision to have a vasectomy or not included: lack of information about risks and benefits, clarification of personal values concerning parenthood after the vasectomy, and undue pressure from partner. On the day of their vasectomy, only 1.9% (95% confidence interval 0.5-4.8%) of men had unresolved decisional conflict. However, most men scored poorly on their knowledge test mean score (58.2+/-13.5%).

CONCLUSION

Men facing the decision about having a vasectomy or not would benefit from a decision support intervention that would address conflicting information and clarification of values.

PRACTICE IMPLICATIONS

Health professionals should provide decision support to men facing the decision about having a vasectomy or not. A decision aid on male sterilization would be useful in this respect.

N-ethyl-N-nitrosourea (ENU) mutagenesis and male fertility research

Male infertility affects about 1 in 25 men in the western world. Conversely, there is an urgent requirement for additional male-based contraceptives, yet progress in both areas has been severely hampered by a lack of knowledge of the biochemistry and physiology of male reproductive function. It is only through a thorough knowledge of these processes that we can hope to insightfully regulate male reproductive function. Without doubt, mouse models will form an important foundation in any future process. In recent years, the chemical mutagen N-ethyl-N-nitrosourea (ENU) has been used widely to identify genes essential for a range of biological systems including male infertility. These studies have shown random mutagenesis is an attractive means of identifying key genes for male fertility. This technique has distinct, but complementary advantages compared to knockout technologies. Specifically, it allows the removal of researcher bias whereby only pre-conceived genes are tested for function; it produces mice with a guaranteed phenotype and allows for the production of allelic series of mice to dissect all aspects of gene function. ENU mouse mutagenesis programs will enable advances in the diagnosis and treatment of human male infertility and ultimately aid in the development of novel male-based contraceptives.