Lots of good advice above. The bottom line is that the penis in question belongs to your son. It is he who should have the option of keeping his foreskin. Absolutely no one else has the right to make that decision on his behalf. There is no compelling life or death issue going on here. The issue concerns basic human rights.
I know that this might sound a bit harsh toward your DH, however even if he does not come around to your line of thinking, if you do not authorise it the doctor cannot circumcise your son. Of course you will have to be diligent in advising all the staff that you do not consent and you will need to keep the baby with you all the time to ensure that nothing takes place behind your back. As others have alluded, the chances are that your DH will come to view your son's intact penis as perfectly normal.
Good luck! We are all supporting you 100%.