"That question bears the basic assumption that abortion is a private and morally neutral choice that only effects the woman."
That answer bears the basic assumption that my question isn't worth answering.
"The first and most obvious is the moral principle: I'm anti-murder, and consider abortion to be the killing of an innocent human being."
The difference being is that the someone who has been born with a parent who couldn't afford a child will lead a horrible life, while the person who has been aborted has just gained a peaceful death without having to worry a thing about poverty. From the basis of what is applicable in the pro-life view, a person who is aborted is murdered, while the people who live in poverty, or are born in such, are lazy.
"In addition to that, abortion is cutting short our population growth, which many economic outlooks (including social security) have relied on."
The economy will obviously be doomed if we don't have 7 billion humans on our planet. Meanwhile, resources are being sucked out of the planet at an exponential rate. A little known fact about abortion is that it curves the economy upward rather than downward. When millions of people have these horrible abortions, they also pay good money for it. If abortion clinics were banned and closed, imagine how well the economy will go when millions of home-done abortions are happening for free.
"Because of abortion, there are fewer problem-solvers being born, fewer productive members being added to society"
There are also millions of people being born. Secondly, the kids being born at this rate are usually the kids of millennials, so are you sure you want to continue the "geniuses are being murdered unborn" argument? Ok, on a serious note, that argument is a bit of a slippery slope, suggesting that if abortion is legal, fewer geniuses are born, because the people who have abortions aren't likely to pay for good education for their children anyway.