Study published in Journal of Paediatrics and Child Health, Volume 44 Issue 1-2, Pages 44 - 49, 4 Sep 2007. The study documents a longitudinal study of over 1000 individuals born in Christchurch New Zealand in mid 1977. The authors concluded, "There was no evidence of an association between neonatal circumcision status and breastfeeding outcomes, or between circumcision status and health and cognitive ability outcomes associated with breastfeeding, and the findings do not support the view that neonatal circumcision disrupts breastfeeding."