From the Canadian Paediatric Society:
www.caringforkids.cps.ca/babies/Circumcision.htm
"The foreskin covers the shaft and head (glans) of a boy's penis. During the early years of a boy's life, the foreskin separates from the glans. This is a natural process that occurs over time. You do not need to do anything to make it happen. When the foreskin separates, it is said to be "retractable," meaning it can be pulled back. An uncircumcised penis is easy to keep clean and requires no special care:
Keep your baby's penis clean by gently washing the area during his bath. Do not try to pull back the foreskin. Usually, it is not fully retractable until a boy is 3 to 5 years old, or even until after puberty. Never force it. "
American Academy of Pediatrics: Care of The Uncircumcised Penis
http://www.medem.com/search/article_..._typ=NAV_SERCH
"Most boys will be able to retract their foreskins by the time they are 5 years old, yet others will not be able to until the teenage years. As a boy becomes more aware of his body, he will most likely discover how to retract his own foreskin. But foreskin retraction should never be forced. Until separation occurs, do not try to pull the foreskin back - especially an infant's. Forcing the foreskin to retract before it is ready may severely harm the penis and cause pain, bleeding and tears in the skin."
The Royal Australasian College of Physicians
www.racp.edu.au/hpu/paed/circumcision/print.htm
"The foreskin (prepuce) and glans penis enclose a potential cleft, the preputial sac. A preputial space is then formed by a process of desquamation, and the prepuce increasingly separates from the glans.
At the time of birth this process is incomplete in the vast majority of boys, and the foreskin is non-retractable. Complete separation of the foreskin with full retractability occurs in almost all boys by the time of puberty."
I hope these help.