No. It is not a premise; it is a result of other facts of reality:
1. The unborn child is an innocent person.
2. It is never morally permissible to intentionally kill an innocent person.
3. The child is currently gestating inside her mother.
As a result, the mother's body is subject largely to the child's needs until birth.
You're "facts" break down in step 2. There are times--perhaps numerous times--when it is morally impermissible not to kill an innocent person.
Let's take a pertinent example.
A pregnant woman has a disease which can be cured (such as a cancer), but the treatment will kill the fetus. But the woman is so weak already that having a dead fetus in her womb will almost certainly lead to her death. What are the choices?
A. Do nothing. The mother and fetus both die.
B. Give her the treatment. The fetus dies, causes an infection, and the mother dies, too.
C. Abort the fetus and give her the treatment. The fetus dies, but the mother lives to go on and have other children.
The only choice that leads to someone not dying and there being more children is C.
How could this be the morally impermissible choice?
Or take a previous real-world example. A woman is severely dizzy and severely throwing up. She has headaches. A doctor suspects she has a tumor. The only way to know is to perform an MRI. But the MRI will very like hurt or kill the fetus. So the doctor refused to do the MRI or treat the possible tumor.
So the mother had an abortion. Turns out she did have a tumor and would have died. But it was easily treated and she survived.
So why is saving the mother's life instead of killing her with the fetus the supposedly only "morally permissible" choice?
Yes. There is no analog to pregnancy; it is its own unique thing. It is the nature of women to have a child inside of them. The woman isn't "sacrificing her own bodily autonomy". The nature of being a woman is that sometimes you get pregnant.
The problem with that stance is not the fact that women sometimes get pregnant. It is the belief that, since she is pregnant, she no longer has sovereignty over he own body. That other people, specifically men who never had to personally deal with the sometimes hard choices associated with pregnancy, can overrule her decisions about her own body. That she is nothing more than an incubator, with no more say over what happens to herself than a mechanical one.
For almost every other circumstance, the individual has the final say over their own body and bodily parts. Even after you're dead, doctors cannot take parts of your body without permission. But because someone decided that a developing human being is exactly like a fully developed, independent human being, the mother has no say over her own body and health. And the people who makes these rules (i.e. men) never have that right taken away from them.
That's what makes women mad.
Just because you can get pregnant doesn't mean you should lose control of your own body. Especially if you didn't have any choice if you got pregnant or not. Especially if it might kill you.
Fact #2 is not a "fact" at all, but an ill-conceived "moral" opinion.
(Although it is good to know that you're against the death penalty.
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