There has been a significant shift in the pro-abortion movement over the last few years. As biological knowledge increases and medical science pushes back the boundary of viability, it has become harder and harder for them to argue that there's ambiguity about when life begins -- in fact, if you see the 'blob of tissue' argument from a pro-choicer now, you know that they are behind the times & out of the loop on the trendy pro-choice arguments.
The current pro-abortion strategy has two main arguments. One, slightly similar to the outdated one, substitutes the nebulous concept of 'personhood' or a 'soul' instead of 'life.' They say that an unborn child does (or might) not have 'full personhood' -- whatever that means -- so their rights are inferior to adults. What's interesting is the shift from a measurable, concrete standard (the existence of human life) to a spiritual/metaphysical one (the existence of a soul). And they say we're the ones trying to legislate our morality.
The other stance is more starkly honest. These pro-abortion types will freely acknowledge that abortion is the voluntary killing of a human being. Some will even use the word "murder." But they argue that circumstances make this choice a preferable or even noble one.
Neither of these are winning arguments in the long run.
The "personhood" argument is self-defeating, if you strip it to its essence.
If the argument is simply: "rights accrue to persons and the unborn are not persons" then it is not an argument, it is so-called begging the question: a restatement of the premise that needs defending in a way that looks like a rpoof of the premise.
If you attempt to analyze the argument and inspect what is there in the word "person" that an embryo lacks, you discover that it is personality. Indeed, an unborn cannot exhibit any personality traits, -- he cannot be funny, or earnest, or kind, or what have you. Accordingly, we, adults, do not develop attachment to them like we do to more developed babies. Let us concede that, at least for the sake of the further argument.
Each time we link a right to a stage in development, we do so because there is an ability to do something, that was previously lacking. Now that the child has the ability, we can consider whether it is also a right. For example, children are not mentally or physically able to drive cars, so they cannot possibly have a right to drive a car on a public road. Some adults have no ability to explain calculus, so they have no right to teach college math (even if the college wants to hire them for that purpose). Learn to drive, and you get a right to drive; earn a PhD and you get a right to teach advanced stuff.
Well, what is the ability needed to live? Answer: be a fertilized egg. If an embryo lives, he is old enough to live. If he is a human embryo, killing him is murder.