Circumcision - Does it Affect Penis Size?
Length when erect:
Average erect penis length was 16.0 cm (95% CI 12.2-19.8) in 156 White men aged 18-55 years (mean 33) in Sydney, Australia [Richters et al., 1995]. Length in the 102 who were circumcised was 0.8 cm (5% or 1/20th) less than length in the 43 who were uncircumcised. The most likely explanation for this difference is NOT that circumcision reduces penis length, but rather the age difference of the circumcised and uncircumcised men, where in Australia uncircumcised men are younger, owing to the decline in circumcision from the mid-1970s onwards. The reason that this is important is because testosterone is higher in younger men and declines with age. Testosterone maintains the size of the penis. Loss of testosterone with age is associated with some penile shrinkage. Erectile dysfunction increases with age and this is associated with penile shrinkage. One might therefore question the speculation by Richters et al. in their attempt to explain their finding. They suggested that "insufficient residual foreskin in some uncircumcised men may have tethered their erections". If their hypothesis had any validity then: (1) The tethering suggestion would need to take into consideration the type of circumcision the men had had decades before. Given their age and the time of the study (early 90s) they would have been circumcised in the 1970s or earlier. At this time infant circumcision was done in Australia by use of bone-cutters, and gave a very tight circumcision with no loose skin, even when the penis was not erect, i.e., most or all of the foreskin would have been removed. The method used for approx. 70% of infant circumcisions in Australia these days is by use of the Plastibell technique, which gives a "looser" circumcision, so no tethering would occur; therefore this should not affect length of the erect penis when the male becomes an adult. (2) Another possibility is that because the men in the study measured their penis themselves, and a proportion of uncircumcised men have a foreskin that extends beyond the penis even when it is erect, the men may have included this extra skin in the measurement they made. This would lead to an over-estimation, when in reality, for just the penis itself, the length might not differ. The senior author on this paper, Basil Donovan, in fact told me that they attempted to employ a sex worker as a research assistant to take the measurements, but this didn't end up working out so they had to allow the men to do it themselves.
Circumference of the erect penis:
• At the base - 13.5 cm (95% CI 10.716.2)
• Shaft just below coronal ridge 12.4 cm (95% CI 10.014.8)
• Glans 11.9 cm (95% CI 9.614.2).
Thus there was no significant difference between the circumcised and uncircumcised.
PS: The author notes that the means of all of the dimensions above are the same as the those for his own measurements, except for his glans, which has a circumference of 13 cm.