Changes

}}</ref> Øster (1968) found that the incidence of fusion of the foreskin with the glans penis steadily declines with increasing age and foreskin retractability increases with age.<ref name="Øster1968"/> Kayaba ''et al''. (1996) also investigated the development of foreskin retraction in boys from age 0 to age 15.5 Kayaba ''et al''. also reported increasing retractability with increasing age. Kayaba ''et al''. reported that about only 42 percent of boys aged 8-10 have fully retractile foreskin, but the percentage increases to 62.9 percent in boys aged 11-15.<ref>{{REFjournal |last=Kayaba |first=H |author-link= |last2=Tamura |first2=H |author2-link= |last3=Kitajima |first3=S |author3-link= |last4=Fujiwara |first4=Y |author4-link= |last5=Kato |first5=T |author5-link= |last6=Kato |first6=T |author6-link= |etal=no |title=Analysis of shape and retractability of the prepuce in 603 Japanese boys. |trans-title= |language= |journal=J Urol |location= |date=1996 |volume=156 |issue=5 |pages=1813-5 |url=http://www.cirp.org/library/normal/kayaba/ |quote= |pubmedID=8863623 |pubmedCID= |DOI= |accessdate=}}</ref> Imamura (1997) reported that 77 percent of boys aged 11-15 had retractile foreskin.6 <ref>{{REFjournal |last=Imamura |first=E |author-link= |etal=no |title=Phimosis of infants and young children in Japan |trans-title= |language= |journal=Acta Paediatr Jpn |location= |date=1997 |volume=39 |issue=4 |pages=403-5 |url=http://www.cirp.org/library/normal/imamura1/ |quote= |pubmedID=9316279 |pubmedCID= |DOI= |accessdate=2019-11-08}}</ref> Thorvaldsen & Meyhoff (2005) conducted a survey of 4000 young men in Denmark.9 They report that the mean age of first foreskin retraction is 10.4 years in Denmark.<ref name="Thorvaldsen">{{REFjournal