Well I would believe in the womb. i would believe in the womb as soon as life is created it chooses to live or die. It's aware of the outside world, can hear, and studies have shown music and other things work to make a child smarter.
I tried this myself while I was pregnant, and after he was born the first time i played the music, he turned his head towards that direction many times when I played it.
If people have an eternal spirit or soul a good bet would be it enters the fetus around the third week. Why? It would be rational that it would come into the body by some organ. The still, somewhat mysterious pineal gland begins to form at this time.Could the fetus then be sentient; maybe. Of course this only a speculation.