Strongly recommend not using this argument, or any of the ones showing up in this sub-thread. No one is going to be convinced on any of this. The people trying to ban abortion will never, ever be convinced by arguments about when life begins -- and will likely just become more certain that the pro choice crowd are full of callous monsters that don't grant dignity to life.
Read A Defense of Abortion, Judith Jarvis. It is the argument.
In a nutshell: it doesn't matter if the fetus is alive/a human/has a soul/whatever. You can grant that it is a full human being with rights from the beginning, even. Our ethical rules place autonomy of your own body hierarchically higher than preserving the life of someone else. That must be true or else it would be perfectly reasonable to harvest extra organs from people without their consent, take any or all property from citizens without cause to give to the needy, or draft individuals into whatever charitable work you wanted with no due process. There are very strict limits on how much charity a person can be mandated to participate in, and that limit is usually down to transient circumstances and taxes. It certainly does not dive into your flesh.
The state has no business enforcing control over decisions an individual makes about the contents of their own uterus, even if those decisions may lead to a death.
Whether or not it is RIGHT or GOOD to get an abortion doesn't even matter and, frankly, isn't worth debating. That is a subjective question. All that matters is whether the state is allowed to step in and prevent it from happening -- and they aren't.
The only thing marking a clear difference between a fetus and any other person is the fetus's need of the womb to live. And unfortunately for the fetus, one person's need of some service to live is not sufficient to enslave another.