Optimal time for neonatal circumcision

Baby circumcision remains a widely practiced procedure. Therefore it is important for pediatric surgeons/urologists to perform circumcision safely with minimal trauma to the neonate. This study shows that painless circumcision is possible in almost all newborns if it is performed during the first week after birth.
— J Pediatr Urol. 2009 Oct;5(5):359-62. doi: 10.1016/j.jpurol.2009.01.002. Epub 2009 Feb 14.

This study shows that best age for painless circumcision in newborns is during the first week after birth.