Perhaps because, under the influence of the relentless propaganda machine, you've forgotten that "choose" is a transitive verb. The act of "choosing" cannot, cannot, be separated from the object that is chosen.
Excepting the extremely rare preteen-victim-of-incestuous-rape situations, a woman who is pregnant with a child she doesn't want has already chosen to have sex under circumstances in which she could conceive a child she's not willing or competent to rear. That is, she has demonstrated that she does not have the discernment to make wise decisions regarding the life of another person.
As you mention, gogeo, she probably shouldn't be in the position of rearing a child, without a considerable development of maturity and judgment. Adoption would be a much better solution for many children born under these circumstances.
Brilliant reminder oh Mrs. T-C. I have long lost the ability to think even slightly academically, I blame it all on my 24 week old "choice" who is convinced that my ribs are his special comfort zone.