Most of the studies I am aware of regarding the normal age of retraction are out of Asia. Interestingly, I saw a couple of French studies that involved retraction and steroid creams on boys at the age of 5, which made me wonder if there was some kind of medical recommendation regarding physiologic phimosis going on in France? Here are the abstracts about normal retraction age:
Hinyokika Kiyo. 2004 May;50(5):305-8.
[Preputial development in Japanese boys]
Ishikawa E, Kawakita M.
Department of Urology, Ishikawa clinic.
The natural course of preputial development is still not clearly understood. The preputial retractability was evaluated in 242 Japanese boys. The incidence of having a retractable prepuce gradually increased with age from 0% at age 1 year to 77% by the age of 11 to 15 years.
In 48 boys, preputial development was followed up for 2 to 10 years with the self-retract maneuver. Non-retractable prepuce was found in 9 boys, which then became retractable within 2-7 years. The prepuce became retractable in most of the boys with balanoposthitis. In conclusion, forced retraction or circumcision is unnecessary for phimosis in boys with or without balanoposthitis.
Zhonghua Nan Ke Xue. 2006 Mar;12(3):249-50.[Analysis of shape and retractability of the prepuce in 1,015 Chinese boys aged from 0 to 18 years old][Article in Chinese]
Wang MH, Wang ZX, Sun M, Jiang X, Hu TZ.
Department of Pediatric Surgery, West China Hospital, Sichuan University, Chengdou, China. firstname.lastname@example.org
OBJECTIVE: To evaluate the characteristics of the preputial development in Chinese boys and indications as well as occasion of circumcision. METHODS: The shape and retractability of prepuce were evaluated in 1,015 Chinese boys from 0 to 18 years old without heteroplasia of prepuce and penis. RESULTS: Ratio of children with phimosis decreases progressively with increasing age, from 64.09% in the first group (0 approximately 3 years old) to 7.66% in the fourth group (11 approximately 18 years old).
CONCLUSION: Phimosis and incomplete separation of the prepuce is normal in the neonate and infant. Prepuce will separate from the glans progressively till adolescence, so it's unnecessary to perform circumcision for them when without any complications.
BJU Int. 1999 Jul;84(1):101-2.
The incidence of phimosis in boys.Shankar KR, Rickwood AM.
Department of Paediatric Urology, Alder Hey Children's Hospital, Liverpool, UK.
OBJECTIVE: To establish the incidence of pathological phimosis in boys. PATIENTS AND METHODS: A 2-year review of circumcisions was performed for phimosis among a known population of boys, with the histological findings of the circumcision specimens assessed. RESULTS: Sixty-two boys (all but one aged 5-14 years) had typical pathological (cicatrizing) phimosis and among the 51 circumcision specimens examined histologically, 43 (84%) showed appearances of balanitis xerotica obliterans. During the same period, 30 boys were circumcised for developmental unretractability of the foreskin ('physiological phimosis'). CONCLUSIONS: The incidence of pathological phimosis in boys was 0.4 cases/1000 boys per year, or 0. 6% of boys affected by their 15th birthday
, a value lower than previous estimates and exceeded more than eight-fold by the proportion of English boys currently circumcised for 'phimosis'.