For information regarding the Catholic teaching on routine infant circumcision, please refer to the following links:
To Circumcise or Not to Circumcise published by the Catholic Health Association of the United States
From the Council of Florence:
"It (the Catholic Church) firmly believes, professes and teaches that the legal prescriptions of the old Testament or the Mosaic law, which are divided into ceremonies, holy sacrifices and sacraments, because they were instituted to signify something in the future, although they were adequate for the divine cult of that age, once our lord Jesus Christ who was signified by them had come, came to an end and the sacraments of the new Testament had their beginning. Whoever, after the passion, places his hope in the legal prescriptions and submits himself to them as necessary for salvation and as if faith in Christ without them could not save, sins mortally. It does not deny that from Christ’s passion until the promulgation of the gospel they could have been retained, provided they were in no way believed to be necessary for salvation. But it asserts that after the promulgation of the gospel they cannot be observed without loss of eternal salvation. Therefore it denounces all who after that time observe circumcision, the sabbath and other legal prescriptions as strangers to the faith of Christ and unable to share in eternal salvation, unless they recoil at some time from these errors. Therefore it strictly orders all who glory in the name of Christian, not to practice circumcision either before or after baptism, since whether or not they place their hope in it, it cannot possibly be observed without loss of eternal salvation."
(Entire text of the Council can be read here.)
To summarize, as a matter of faith, the practice of circumcision has been authoritatively and irrefutably denounced by the Church from the Council of Jerusalem in the book of Acts from Scripture and several times since. Catholics are forbidden from circumcising as a practice of faith. From a medical standpoint, because no authoritative medical body recommends it as routine practice, infant circumcision without direct medical need is thought to be in violation of standard Catholic medical ethics. See Evidence Based Birth's article Evidence and Ethics: Circumcision for a comprehensive review of the best and most up to date medical research on the subject.