Ok, I've got a question for you.
Say there is a drug which is safe for an adult to take, but lethal for babies, and is transmitted in breastmilk to the extent that it would kill the baby.
Mum knows this, takes the drug knowing it will kill the baby, and then breastfeeds her child. Child dies.
Should she be liable for murder? If someone can do whatever they please with their own body, then does that extent do deliberately poisoning her baby? Does that freedom to do what you want with your body extend to the freedom to hit and punch? Or do you accept that actually you don't have compete freedom to do what you want with your own body, especially when it harms someone else?
Ah, you say, but an unborn baby isn't a person. It's not a legal person, it can't bring legal action, it can't own property etc, but after 28w, legally it has enough 'personhood' that deliberately killing it is (with very limited exceptions) an offence akon to murder in seriousness.
You also are not considering that although morally the woman may have the right to end the pregnancy, she should not have the right to decide what happens to someone else's body, and to choose to kill it, when if born it would survive at that stage.