Seeing her like that, I suddenly remember that, when I was a kid, I often wished my mother was a centauress. It's a strange wish for a child, I know, but I always loved horse and my parents were too poor to let me have equitation lessons.
That was my wicked idea: Officer Butz will be my new mother!
First, I wished centaurs always existed, living peacefully alongside humanity. Then, I wished my creation was born as Samantha Butz, a kind centauress in her private life, but the same strict officer as ever in her police work. The third wish my plan needed was to make her young enough to be an expectant mother.
It was time for the second part of the plans: Altering myself.
First, I wished my clothes away, not going to need them for now. After that, I wished I was safely tucked in her uterus, immersed in amniotic fluid, Samantha feeding me through my umbilical cord. At that time, it was very cramped in my new mother unreasonably distended horse-belly, me still being in my adult human body. But I wished that my body to change progressively to the one of a centauric being about to be birthed. The change took a month.
I know what you think. 'But, a centaur can't learn to ride a horse!' True, but they don't need to, they are their own horses to ride, and they live all their lives doing it!