Sad Emo, page 4 had some interesting rebuttals, such as this:
"In theory, legal abortion reduces murder by being, in effect, "prenatal capital punishment." But, first, it's not very efficient. Like Herod, we have to eradicate many to get the one we want. While genes and upbringing do affect criminality, there's so much randomness that predicting the destiny of individual fetuses is hard."
However, I disagree for the most part particularly the concept that we have to "eradicate many to get the one we want". The fact is, the vast majority of abortions take place amongst poor, uneducated and poverty stricken women. IMHO, its not a black/white issue, its an issue of limited access to reliable contraceptives and sex education amongst the poor. But in the end it doesn't matter, and the jury is still out as to how much control a human being actually has outside the limitations of genetic and environmental backgrounds. The effects on society of poor, disadvantaged and uneducated mothers living in poverty and giving birth to unwanted, unloved children is cumulative and exponential. Its merely common sense that eliminating or at least reducing the "pool" of children forced into existence and then living in squalor and despair will naturally cut the incidence of future criminal development in a linear fashion.
But there is another issue that is not discussed: access to abortion may provide a second chance to young, uneducated and poor women for whom having to look after a child would completely remove the possibility of getting an education, a good job, etc etc. I.E. allowing these women the chance to create a life for themselves wherein it WOULD be a good environment for raising healthy, happy and loved children. Should a broken condom or moment of thoughtless unprotected sex be a permanent sentence of doom not only on the woman but also upon a child that was created unintentionally? Unwanted children are invariably, unloved children.