OP, I don't think it's that big a deal that you didn't see her during the pregnancy, and I doubt she'll ask about it. I found with mine that during the late stages of pregnancy I didn't want to see most people. I wouldn't have had the energy at all, even if they had come to visit, and I certainly was in no mood to go hang out.
In fact you may be the best kind of friend a pregnant woman could have. You're happy when she tells you, and then by the time she's really uncomfortable with even going out in public because how she looks, and how much work it is, and she just really wants to be left alone instead of questioned daily about her blood pressure, and when the due date is, and asked to describe the nursery for the 10,000 time, you are willing to leave her alone. Which was all I really wanted by about six months in. Just to be left alone by the crazy people. Then you show up again when the baby is born, and you're happy that everything went well. I don't think you need to feel any guilt about this at all. I think most pregnant women understand that lots of people are sensitive about pregnancy/young children for one reason or another. It's not you failing as her friend, it just is what it is. And you dealt with it, and didn't take it out on her. Your fine in my book.
Also, totally can see this phobia. "What to Expect, when You're Expecting" = #5 on my Top Scariest books of all time. I'm shocked it's not the centerpiece of a scared straight program for scrabble playing teens somewhere.