Abstract
Physical attractiveness is based on idealizations. In many societies, particularly Western societies, a physically attractive woman has skin that is smooth and without blemishes, large breasts, a narrow waist, and wide hips; she is also slim. A physically attractive male is moderately but not excessively muscular, slim to moderate in build, and endowed with a large penis. These and many other idealized attributes vary across societies and across time.
Idealized conceptualizations of physical appearance spawn industries that range from cosmetic aids to cosmetic surgery; they stimulate dieting and exercise that can range from healthy to unhealthy, and they create stigma that leads to, for example, fat shaming.
Stigma, however, is not created solely by a failure to measure up to the ideal. Stigma arises, also, from the failure to recognize what is normal in the population. As an example, preoccupation with penile length may make some men feel inadequate, and may make others attempt penile elongation using methods that are potentially harmful to the organ 1 ; this is the scenario despite the ownership of a penis that is well within the normal range. Knowing what is normal in the population is therefore important.
Penile Length: What Is Normal?
Veale et al 2 described a PRISMA-compliant systematic review of studies in which adult penile length was measured by a health professional who used a standardized procedure; all studies were required to have a sample of at least 50 men. Studies were excluded if the sample had subjects with a congenital or acquired abnormality of the penis, or if the subjects had undergone penile surgery, or if the subjects were recruited for erectile dysfunction or small penis size.
There were 20 studies from 16 countries in Europe, Asia, Africa, and North America. The pooled sample size was 15,521. The authors calculated a weighted average (basing weighting on sample size) with a pooled standard deviation (SD) and created nomograms with percentiles for penis length and penis circumferences.
They reported that in 10,704 men the mean (SD) length of the flaccid, pendulous penis was 9.16 (1.57) cm; the mean (SD) length of the stretched penis in 14,160 men was 13.24 (1.89) cm; and the mean (SD) length of the erect penis in 692 men was 13.12 (1.66) cm. They also reported that the mean (SD) circumference of the flaccid penis in 9,407 men was 9.31 (0.90) cm and that of the erect penis in 381 men was 11.66 (1.10) cm. Height explained just 4% to 36% of the variance in penile length.
The most important message from this study is that, across countries and continents, the mean length of the penis is 9.2 cm when flaccid and 13.1 cm when erect, and the mean circumference is 11.7 cm when erect. Because the mean ±1 SD includes about two-thirds of the population, about two-thirds of men have an erect penis in the 11.4 to 14.8 cm range.
There are obvious limitations in studies of this nature. For example, the size of the flaccid penis is markedly sensitive to ambient temperature, emotional reactions (that range from embarrassment to arousal), and other factors; so, no matter how standardized the assessment procedure, a Hawthorne effect could compromise the validity of measurements. Regrettably, the most important variable, the length of an erect penis, had the smallest sample size in the pooled analysis.
Of note, different methods are described for the measurement of penile length. 3 One method that is commonly adopted is to measure from the root of the penis, with the pubic fat pushed to the bone, along the dorsal curvature of the penis and to the meatus at the tip of the penis. The circumference is measured at the base or at the midshaft.
An additional point that must be considered 4 is that men view their own penis from above, but the penises of other men, in pictures or in real life, from in front. The former length is diminished by a parallax error, whereas the latter length is not. So, men may falsely conclude, from appearances, that their penis is small. Therefore, while counseling men about the length of the normal penis, this point must also be made.
The Appearance of the Vulva: What Is Normal?
Preoccupation with the appearance of the vulva may make some women feel inadequate or ashamed, and may drive them to cosmetic surgery; this is the case despite the presence of genital characteristics that are well within the normal range. So, as with penile length, knowing what is normal in the population is important for vulvar morphology as well. In this context, Kreklau et al 5 described the results of a single-center Swiss study that examined normal vulvar morphology in white women aged 15 to 84 years. Women of other races were excluded to keep the sample homogeneous. Women were also excluded if they were pregnant or had vulvar disease.
The sample was recruited from gynecological and urogynecological outpatient clinics in a cantonal hospital. There were approximately 100 women in each decade of life between age 15 and 75 years, and 51 women in the age range 75 to 84 years. The total sample size was 657. The body mass index of the sample increased from approximately 23 in the youngest to approximately 27 in the oldest. About a third of the sample was nulliparous.
The authors reported a number of findings. The median length of the clitoris decreased from 6 to 4 mm with increasing age; the median width was 2 mm at all ages. The median length of the labia majora was about 75 to 80 mm in different decades of life. There was little difference in length between the left and right labia. The length was greatest in the middle decades of life and least in the youngest and oldest groups of women. The median length of the labia minora was 30 to 50 mm in different age groups; the median width was 10 to 15 mm. Again, there was little difference between the left and right labia. The dimensions of the labia minora were greatest in the middle decades of life and dropped sharply in the later decades.
The authors also presented data for fifth and ninety-fifth percentiles for all measurements. For example, at the ninety-fifth percentile and in different age decades, the width of the labia minora varied from 25 to 34 mm. Finally, the authors also provided data on other measurements, such as the distance between the clitoris and the urethra, the length of the introitus, and the length of the perineum.
An important message is that average clitoris is 4 to 6 mm long and 2 mm wide; the labia majora are 75 to 80 mm in length; the labia minora are 30 to 50 mm in length and 10 to 15 mm in width. Most dimensions are greatest in the middle decades of life and fall later.
The usefulness of this article particularly lies in the data presented for the fifth and ninety-fifth percentiles for various measurements in different decades of life. These can guide the interpretation of the boundaries of what is normal in the population.
General Comments
Given the almost worldwide preoccupation with genital appearances, it is surprising that there are so few studies on the subject. In men, larger, population-based studies need to examine and construct nomograms particularly for erect penile dimensions in different ethnic groups. In women, population-based studies need to provide descriptors particularly of labia minora morphology. These studies particularly need to examine persons of reproductive age, because preoccupation with appearance is maximum in this age group. Finally, what is normal needs to be widely disseminated so that exaggerated expectations do not obsess the population.
