A staple argument for abortion is the appeal to body autonomy: a woman has ownership of her body. She has a right to control her own body. Her body, her choice. You can't justifiably force someone to donate the use of their body, even for a worthy cause.
The argument has some prima facie appeal. Most of us believe adults are entitled to a measure of independence. But by the same token, most of us don't think that's absolute.
But let's play along with the principle for the sake of argument. And let's take a comparison: suppose I own a private jet or perhaps a private submarine. I'm superrich. Submarines are my hobby.
If you're a passenger on my plane or sub, do I have the right to flush you out the airlock? After all, it's my plane! It's my submarine! As a passenger, you're leeching off the life-support system on my private jet or sub. You can't survive outside that artificial environment. You can't survive at 40 thousand altitude outside the cabin. You can't survive 10 thousand feet deep outside the sub. You can't survive without the food and drink, climate control, oxygen, &c. So you're a freeloader!
If I flush you out the airlock, that's no one's business but my own. To critics I say, Keep your hands off my U-boat!
Perhaps a feminist would object that the passenger is a guest, and that's no way to treat a guest.
To begin with, that would be analogous to pregnancy due to consensual sex. But most people who support abortion don't restrict abortion to the rape exception.
I'd add that even if we grant the rape exception for argument's sake, not all passengers are guests. Sometimes a passenger is a stowaway. But does that mean it's all right to flush a stowaway out the airlock?
In addition, consensual sex without contraception involves implied consent to become pregnant. That's an implicit invitation.
So by that logic, even if the passenger is on my plane or submarine by invitation, I'm still entitled to flush them out the airlock–just as a mother is entitled to an abortion even if she consented to sex without contraception. She knew the "risk" of getting pregnant. Moreover, many feminists would say that even if she intended to become pregnant, she still has a right to change her mind at any time.