I didn't mean to say whether the fetus is alive is the relevant question, so apologies for the confusion. It's whether the fetus is a person, in which case, yes being a person does entitle it to rights, none greater than your right to life. That takes primacy over other rights of the mother to terminate the person (assuming it is a person).
It's true that there's no clear answer, but I suggest that this is the question to answer, regardless of where you fall on the debate. Some people think its "heart beat" however you define that, other think its viability outside of the womb, and I'm sure other people have different criteria. But we should look to answer this question and get to a sensible policy.
This is basically the argumentation why many treat conception as the start of life. If you can't know the exact point, then disallow people from guessing and potentially getting it wrong.
"If the fetus is a life," you say, but of course it's alive, it's made of living cells. That's not even the issue really. Something being alive doesn't necessarily say anything about how we should treat it. We don't treat bacteria with respect, or mushrooms, or even most animals. So given that a fetus is alive, does that entitle it to any rights? And if so should those rights have primacy over the rights of the person who is carrying the fetus?