The foreskin is not fully developed at birth and continues to develop during childhood. By about 5 years of age, however, most boys can pull the foreskin back over the head of the penis. There are 2 principle reasons why there might be difficulty doing this: a narrow opening (known as a phimosis) and attachments between the inside of the foreskin and the underlying head of the penis (referred to as prepucial adhesions). Difficulty in pulling the foreskin back can lead to problems with hygiene and cause infections underneath the foreskin – so-called balanitis.