In LLL's Facts about Breastfeeding 1995 the following reference is listed in
relation to

"The observed deterioration in male infants' ability to breastfeed after
circumcision may potentially contribute to breastfeeding failure..."

Howard, C. et al.  Acetaminophen analgesia in neonatal circumcision:  the
effect on pain.  Pediatrics 1994;93(4):641-46.

Hope this helps.

Natalie J. Shenk, BS IBCLC
Ohio, USA