I was recently shown a scan of a baby, not the normal sort of scan I'd seen before and I found it a bit disturbing. I think mums to be should keep scans to themselves. I mean, you wouldn't go around showing an ex-ray of your lung or a mammogram. The reason for a scan is to make sure everything is ok and I really don't see the point in 'sharing' the scan photo with anyone.
Apart from anything else, I don't think it's natural to have such a strong image of a baby that isn't yet born and sharing it around family and friends. It's a bit like buying a present for someone that you've bought in her presence and then saying, I'll wrap it and give it to you at Christmas.