It took my DH a year after DS#2 was born (and not cut) to come around. He finally agrees that we won't circ any future children. He isn't an intactavist, but he knows it isn't needed. Now is not the time to try and convience your DH that you are right. Be very polite, be very firm, tell him this child will not be circumcised. It's not DHs decision, it's not your decision, it's your sons decision that he will make when he is older.
DS#1 is cut, my choice, didn't realize I had one. DS#2 is intact. We fought a lot about it, but I was very firm and never faultered. Finally when I was around 7 months pregnant I told him that DS won't be cut, that is the final decision, he doesn't get a say. We quit talking about it, and DH eventually followed suit.