Discussion

Across cultural, religious and health-related differences around the world, the pleasures of sexual intimacy and orgasm are ubiquitously considered important for well-being and health. In the present Danish study, having a good sex life was rated as 'important', 'very important' or 'extremely important' by 87% of female and 89% of male participants. Among factors that have previously been found to affect the prevalence of sexual problems are age, cultural background, marital status, parity, educational level, tobacco smoking, personality traits and both mental and physical health problems.[10,15–17,19–22] Recently, we showed that 11% of sexually active Danish men and women fulfilled rather stringent criteria for having at least one sexual dysfunction.[15–17] In the present work, we focused on the possible role of the ~40–50 cm2 penile foreskin,[23,24] which has caused more controversy than probably any other part of the human body. Before turning to the more disquieting findings, it should be emphasized that most men in our study, whether circumcised or not, reported only occasional sexual function difficulties. Likewise, most women with circumcised spouses reported that their sexual needs were fulfilled (62%) and did not complain about frequent sexual function difficulties (69%).

Impact of Circumcision on Male Sexual Function

In accordance with prior studies,[10,11,25] we found circumcision to have little impact on most sexual domains in men. Circumcised and uncircumcised men had comparable sexual histories, they considered a good sex life equally important, they were equally likely to be sexually active, and their frequencies of partner-related sexual activity were similar. The only behavioural difference was that circumcised men were more likely than uncircumcised men to report a lifetime history of 10 or more sex partners. Considering all sexual function difficulties together revealed no difference, but circumcised men were three times more likely than uncircumcised men to experience frequent orgasm difficulties which, according to an international expert panel, are either psychogenic or due to reduced penile sensitivity.[26] Robustness analyses showed that these difficulties of circumcised men were not explained by an excess of anxiety or depression in this group. This suggests that reduced penile sensitivity may, at least in part, explain the difference, a situation that has been recognized for centuries[27] and supported by recent neurophysiological studies.[25,28,29] The more frequent orgasm difficulties of circumcised men and their partners are not only a concern from a sexual pleasure perspective. The ability to achieve orgasm is a major determinant of overall sexual life satisfaction and marital satisfaction,[20,30–33] and persons who rarely experience orgasm may even be a group with increased overall mortality.[34]

Historically, reduced penile sensitivity was not an unintended side effect of circumcision. Medieval rabbi, physician and philosopher Moses Maimonides (1135–1204) stated that circumcision was required to 'cause man to be moderate', because circumcision 'weakens the power of sexual excitement' and 'lessens the natural enjoyment'.[27] In the 19th century, pre-occupation with the dangers of phimosis, masturbation and an ill-defined syndrome called spermatorrhoea gave rise to a series of preventive measures, including chastity belts, straight waistcoats, iatrogenic urethral inflammation and other measures to reduce sexual excitability.[35] These procedures eventually lost clinical relevance as circumcision grew in popularity to become the favoured method of preventing and treating the ill-regarded habit of masturbation.[36–41]

Logic suggests that amputation of the foreskin with its abundance of sensory nerve endings and specialized end organs[8] entails reduced penile sensitivity. Nevertheless, some authors maintain that there is either no difference in penile sensitivity between circumcised and uncircumcised men[42] or that the reduced sensitivity is advantageous because it prolongs the intravaginal ejaculation latency time.[25,28] One small study that was briefly mentioned in Masters and Johnson's pioneer work on sexual physiology has been repeatedly, yet incorrectly, cited as evidence of no sensitivity loss following circumcision. Comparing 35 circumcised and 35 uncircumcised men, these authors disproved contemporary claims of increased sensitivity of the circumcised glans,[43] but their findings have been misused as evidence against the opposite concern, namely that circumcision may cause reduced penile sensitivity. Other underpowered reports,[44–46] including a much cited study of sexual function in 15 men before and after circumcision,[44] have led authors to conclude that circumcision has no impact on male sexual function. Other authors reached the opposite conclusion, namely that circumcision reduces penile sensitivity.[47–50] As with the negative studies, however, these studies were small, based on self-selected participants, or lacked detailed accounts of the methods used.

In a few studies,[25,28,29] participants measured the time from vaginal intromission to intravaginal ejaculation and were subjected to neurophysiologic testing. In Turkey, 42 men without penile pathology reported longer intravaginal ejaculation latency times after circumcision,[28] and the reduced penile sensitivity was confirmed by increased post-circumcision pudendal nerve evoked potentials, which the authors attributed to the loss of sensory receptors.[25] In the USA, 91 circumcised and 68 uncircumcised men were subjected to the Semmes–Weinstein monofilament touch test. Five locations on the uncircumcised penis that are routinely removed at circumcision were found to be more sensitive than the ventral circumcision scar, the most sensitive part of the circumcised penis.[29]

Only two population-based studies can be meaningfully compared with our findings in men.[9–11] Among 1410 US men aged 18–59 years, of whom ~75% were circumcised, prevalence estimates were 10% for erectile dysfunction and 8% for orgasm problems. These estimates are close to the prevalence of frequent erectile difficulties (10%) and frequent orgasm difficulties (11%) among circumcised men in our study, but premature ejaculation was much more common in the US survey (31%) than in ours (12%). In agreement with our findings, the authors reported no association of circumcision status with sexual dysfunction overall or with premature ejaculation (OR = 0.87), erectile dysfunction (OR = 1.30) or low desire (OR = 1.64).[10] Unfortunately, the authors did not present an OR for the association between circumcision status and orgasm difficulties, the only male difficulty that was associated with circumcision status in our study. A survey of 10 173 Australian men aged 16–59 years showed a number of associations between sociodemographic and cultural factors on one side and circumcision status on the other. However, because the authors adjusted only for age when evaluating possible associations between circumcision status and sexual dysfunctions, the reported reduced rates of dyspareunia and erectile difficulties in circumcised men are hard to interpret.[11]

Two randomized trials evaluating the impact of male circumcision on risk of female-to-male transmission of HIV included personal interviews to address possible side effects of circumcision on sexual function and sexual satisfaction.[51,52] Among 18- to 24-year-old men in Kenya,[52] the overall prevalence of sexual problems decreased from 24% at baseline to 6% 2 years after the circumcision. The authors provided no explanation for this noticeable decline in sexual problems over time but felt reassured by a similar drop in sexual problems in the uncircumcised group (26% at baseline; 6% at 2 years). Measurement problems and drop out of men who experienced sexual problems during follow-up but were reluctant to report them in a personal interview with representatives of the circumcision team need consideration. Among 15- to 49-year-old men in neighbouring Uganda,[51] the prevalence of sexual difficulties was implausibly low and remained unchanged during follow-up. Specifically, 98.9% of circumcised men and 99.9% of uncircumcised men reported satisfaction with sexual intercourse at 12 months. As pointed out by others, bias needs consideration in these African studies because interviewers were not blinded to participants' circumcision status.[53]

Impact of Circumcision on Female Sexual Function

Studies on the impact of male circumcision on women's sexual functioning are generally small or hampered by questionable, or overtly flawed, methodologies.[54–58] In one study, 145 mothers in Iowa, USA, expressed a clear preference for the circumcised penis. However, considering that 83% of participants had no sexual experience with uncircumcised men and 89% had their sons circumcised shortly before the interview, any other result would have been surprising.[54] In another US survey, 139 women who had sexual experience with both circumcised and uncircumcised men reported that they more often achieved orgasm with an uncircumcised partner. However, because participants were recruited through an anti-circumcision newsletter, results should be viewed with scepticism.[55] Among 35 women in Australia, participants were more likely to have experienced vaginal dryness with circumcised partners, but insufficient methodological detail was provided.[58] Authors in a circumcision trial in Africa reported similar or greater levels of sexual satisfaction among female partners after the spouse's circumcision.[56] However, by focusing on changes in overall sexual satisfaction, readers were uninformed about the actual levels of sexual satisfaction reported. This is potentially problematic, considering the implausibly high levels of sexual satisfaction reported by men in that same study.[51]

Nowadays, most people will agree that, at least within the frames of heterosexual marriage, the ability of men and women to experience sexual intimacy and orgasm is important to health and well-being. According to the WHO, approximately 660 million men, 30–33% of the world's male population, have been circumcised as a matter of parental decision before age 15 years.[59] Consequently, our findings of increased rates of orgasm difficulties in circumcised men and of a variety of sexual troubles among their spouses are potentially relevant to millions of people around the world.

Strengths and Limitations

Our study is the first population-based study in Europe to examine possible sexual consequences of circumcision and the first to systematically address associations between circumcision status and sexual difficulties in both men and women. Other assets include the large size of our study, and the fact that Denmark with its relatively liberal views on sexual matters is a favourable setting for collecting this kind of sensitive information.[60]

Neonatal circumcision is uncommon in Denmark, explaining the low overall prevalence of circumcision in this country. Of circumcised male participants in our study, only 15% had been circumcised before age 6 months; among spouses of female participants, the corresponding proportion was 28%. Consequently, our study had limited statistical power to address in detail whether observed associations with sexual difficulties applied particularly to neonatal circumcisions or operations performed after infancy. We observed no difference between those circumcised before or after age 6 months, but this should be studied further in other settings where neonatal circumcision is more common.

With overall participation rates of 48% among men and 54% among women, our findings need cautious interpretation. Participants tended to be healthier and better educated and were more often married, middle-aged and residing outside the capital area than non-participants. Higher participation rates in US[9] (79%) and Australian[11] (69%) surveys are probably partly explained by their age restriction to persons <60 years. Reassuringly, restriction to 20- to 69-year-old participants (robustness analysis 3) confirmed our main findings. Theoretically, links between circumcision and sexual dysfunction may be overestimated in our study if higher proportions of sexually well-functioning circumcised men or women with circumcised spouses declined the invitation to take part in the study than corresponding proportions of sexually well-functioning uncircumcised men or spouses of such men. Considering that circumcision is an uncommon procedure in Denmark that rarely causes public attention, selective participation in a general health survey based on one's circumcision status or, among women, the circumcision status of one's spouse seems unlikely. A more relevant limitation is that our findings were limited to participants who had been sexually active with a partner in the last year. Consequently, the degree to which our findings are generalizable to the entire Danish population is uncertain. However, with due socioeconomic reservations, our findings are likely to apply to that majority of Danish men and women who are sexually active with a partner.

As mentioned, our findings need re-examination in settings where neonatal circumcision is more prevalent. Of note, however, they were not the result of unadjusted cultural or religious factors among groups that practice routine circumcision; all main findings were confirmed in robustness analyses restricted to non-Jews and non-Moslems or those with at least one Danish-born parent.

Current evidence shows no role for circumcision in preventing HIV transmission in industrialized parts of the world[61,62] or in reducing the male-to-female transmission of HIV in sub-Saharan Africa.[63] Actually, there are reports of increased risk of HIV transmission during circumcision in resource-poor countries.[64] However, randomized trials[6] have shown that circumcision carried out with appropriate surgical techniques and sterilization procedures may reduce the female-to-male transmission of HIV in Africa. The WHO strategic plan for sexual and reproductive health during 2010–15 includes 'support to countries to monitor the quality and acceptability of male circumcision services as they expand in the African Region and elsewhere' as well as research 'to assess the safety, effectiveness and acceptability of medical devices to facilitate expansion of male circumcision services'.[65] If, as suggested by our findings, circumcision is associated with non-trivial sexual difficulties in a substantial proportion of men and their partners, the continued promotion of male circumcision will constitute an ethical dilemma. Several studies document a widespread belief among African men that circumcised men have better penile sensitivity, enjoy sex more and confer more sexual pleasure to their partners, and these beliefs are among the central arguments for accepting the operation.[66,67] Our study should stimulate an unbiased quest for additional large-scale data on possible sexual consequences of circumcision. In ongoing WHO-sponsored circumcision programmes, we suggest the incorporation of rigorous epidemiological studies of the possible sexual consequences of circumcision. In collaboration with local circumcision programme managers, such activities should be carried out by independent teams of researchers guided by sexual health experts and epidemiologists. In this way, the WHO would signal its dedication to ensuring sexual rights for all, along with its commitment to fighting the HIV epidemic in sub-Saharan Africa.