I think the point is that most pro life advocates argue simply that an unborn child is a human life and the sanctity of human life should be protected. In which case said person should also be against the death penalty, which anecdotally I believe isn't generally the case, which negates their pro life anti-abortion argument. In which case the stance becomes: some human life should be protected and others shouldn't. Now you've opened the door to the fact that not all lives are equal when it comes to the life we have been given and someone else can now judge whether that life should be protected or not. But any human judge is bound to be flawed, because we are human. So do we want to then allow for a flawed individual deciding what lives are worth protecting and which aren't? I'd argue that we apply the logic equally across the board: Either abortions are allowed and so is the death penalty, or abortions are outlawed and so is the death penalty.
I do not argue the point because I am not in favor of babies having the opportunity to live their lives. I argue the point because I think logical arguments should be used universally, not selectively. I am very much in favor of all babies having the opportunity of a life. But until we find a way to make adoptions not cost tens of thousands of dollars, provide completely free healthcare for pregnant mothers who may not want their child, provide completely free and easy universal access to whatever contraception a woman wants to use, we have no business trying to argue the point whether abortions should be legal or illegal. If overnight abortion became outlawed in the US, do you think that would stop all abortions in our society from happening overnight? Absolutely not, people will find ways. So instead of both sides being idiotic and fighting to have things 100% their way, if they would get their shit together and accept compromises, many more babies could have the opportunity for life in a much shorter amount of time than what's being done now.
Sorry for the semi-rant, but when there's something as important as a life involved and people can't see past their own ideals in order for true progress to happen, it just burns my bacon.