I believe whether a baby died because of a miscarriage or was stillborn, they started out with a soul, just like they started out with a heartbeat. However long or short the amount of time was that that little heart beats, it WAS alive.

I found a video clip of a little boy who had a near-death experience and claims to have glimpsed Heaven. Sounds farfetched, right? Well, he brought up relatives who passed on BEFORE he was born............one of whom was a sister that his mother miscarried and his parents NEVER told him about her.
If you go onto Youtube, you can find different (longer) clips if you use the keywords "The little boy who saw Heaven." I just decided to post a clip to a short video.

http://www.youtube.com/watch?v=UYwC2-utH4A