I was really excited to get pregnant and then when I realized I was, I was suddenly like, "Oh no, what did I just do!? My life is over now!" but that's actually a fairly normal reaction I found out, and once the news had time to set it I started getting excited again. I wonder if some of these women just panicked? But I also agree with above posters that I doubt this is a very statistically significant number of women to begin with.
The remorseful moment can be fleeting and the mom-to-be may embrace her new role. Did you experience any of these feelings while with child?