Simple question, if your dependant needs a blood donation to survive, are you forced to donate blood or not? If your dependant needs marrows? would they force you to donate?

The answer is no. Because you have a right to body integrity.

Turn it around, when you are forced to donate blood, marrow and organs (after death) to dependants, then your argument would make sense. Then we could speak aboutwhen the phoetus could be considered a dependant and the responsability of the woman to donate her body to the dependant phoetus.

But right now, you can pay to take your dependant to a nurse home, for example. Or ask for government to step in.

If the dependant is a child, you can give it up for adoption.

You can't do that with a phoetus. The phoetus needs the womb, the umbilical cord and feeds directly from the woman. The phoetus is using the woman's body. That is the difference with a baby and an elder.