It comes down to this: Life begins at conception

 https://www.desmoinesregister.com/story/opinion/readers/2014/10/06/letter-pro-life/16791803/

https://www.princeton.edu/~prolife/articles/embryoquotes2.html#:~:text=Life%20Begins%20at%20Fertilization%20with%20the%20Embryo's%20Conception&text=%22Development%20of%20the%20embryo%20begins,together%20they%20form%20a%20zygote.%22&text=%22Human%20development%20begins%20after%20the,known%20as%20fertilization%20(conception).