Need Advice Ladies!!

There was a blowout a while ago between my boyfriend and my parents. My parents are over it and try to call him, invite us over for dinners, etc.... But he refuses to take part in it. He's also refusing to do anything with them for Christmas! I would just love it if he would suck it up and spend a couple hours with my family! I mean we have been together and are 6 months along with the pregnancy. It stresses me out and I wish he understand this. Any idea how I can get this stubborn man to just give in for the sale of us?