What to do when he doesn't want to anymore...

I am 30 weeks pregnant... and tired of always having to be the one to initiate sex. There was a time when he literally chased me around just to be near me, and now, he spends hours a day on-line looking at porn. I know that Ive put on weight... DUH! Im pregnant... I dont mind being the agressor sometimes, thats just the way it should be... But he wont even touch me unless I initiate, or he's just gotten off the computer from a porn session. What can I do?? Im beginning to get severely depressed by my lack of any kind of sexual attention...