Just wanted to comment on the infertility thing.
We had trouble conceiving this baby (over a year), but there are people who sadly try for even longer without success. It is a heartbreaking state in which to find yourself, cycle after cycle, month after month, and it is made all the more difficult by the reminders (pregnant bellies, little babies, etc) of what you don't have everywhere around you, like miracle fruit just out of reach. You feel sad, guilty, bitter, depressed, and a multitude of other emotions. Often you feel like if you see just one more pregnant woman, you will explode in agony. You find yourself thinking about how unfair the world is and how surely you deserve a baby more than they (whoever this faceless "they" is) do.
Yeah, it's not pretty. However, most of us would never actually say something mean to a pregnant woman; it just might take a bit of time to offer a "congratulations" because we have to go through a round of self loathing first.
And Conchobhar, you sound like a great friend and very sensitive to your friends who are suffering from infertility. You have absolutely no need to feel guilty that you are pregnant, and you sound like you understand how hard it is for them and why they may keep some distance for awhile (not because they hate you but because they are saddened by reminders of what they don't have).
Anyways, I thought I'd offer the infertility perspective now that I'm on the other side. Even I'm worried about hurting people who are having trouble conceiving, and I had trouble myself. There are so many of us, and you never know who they are of all the people around you.