I think if you're pregnant you just want somewhere with a beach and lots of relaxing,
I went to Samoa pregnant (Although didn't do the luxury tourist thing as I was there to work in the hospital) but I always thought it would be a great place for a holiday once the baby (DD) came. I guess Fiji would be similar.
Yummy fruit and food, lots of lovely blue water, a couple of good books....sounds divine! I agree that your budget should get you tehre, especially if you are on the East Coast, Virgin blue/Pacific Blue often does holiday packages

If you are west coast Bali or Thailand have many kid friendly places and would be great.
Enjoy