Abortion and risky sex. The relationship here is surprisingly hard to measure, because it's hard to know just how much sex people are having (I know I lie about it). But it really does seem that people, especially young people, are quite sensitive to the costs of sex. With that in mind, legalized abortion doesn't appear to increase the overall level of sexual activity, though people seem to view abortion as a substitute for ex ante birth control. Looser abortion laws, more risky sex, but not necessarily more overall sex. (I don't know how this squares with recent research on the morning-after pill.)Anyway, like I said, none of this stuff really changes the debate in any meaningful way. These results aren't even all that surprising. And it doesn't even make for good cocktail party chatter. Basically, this post is useless. But it's either this or endless Star Wars Episode III discussions...
Parental notification laws. Two findings. Laws requiring minors to get consent before receiving abortion seem to decrease the incidence of unprotected sex among women by a decent amount, but barely impact the overall sex rate. That leads to finding two: a 1996 study found that parental notification laws lead to lower teen birth rates. (Note: This isn't what I would have expected, though I'm still very much against parental notification laws. Explanation later.)
Child abuse. As you'd expect, legalized abortion seems to have reduced the incidence of child abuse among the cohort of kids born after legalization. The commonsense explanation, of course, is that legalized abortion means fewer unwanted births.
Abortion and crime. The debate here is fascinating, but fairly technical, so read the paper if you want to know the details. Basically, though, Steve Levitt (the Freakonomics guy) and John Donohue first made this connection a few years ago, arguing that about half of the crime decrease in the '90s was due to the fact that, thanks to legalized abortion, there were fewer unwanted children born after 1973, and therefore, fewer criminals around in the '90s. They've been bickering with critics ever since, and from the way Klick presents it, the debate still seems inconclusive.
Abortion and opportunities for women. You'd expect that fewer unplanned pregnancies would mean more opportunities for women. But there are a lot of other factors to try to weed out. (Perhaps women who are more likely to have unplanned pregnancies are less likely to do well in the workplace? Doubtful, but still.) Anyway, two researchers found that abortion legalization was a boon for black women—if not for white women—as far as graduating high school, entering college, and employment goes.
Bargaining positions. This is the best part. Economists Akerlof, Yellen, and Katz argued that women who are willing to have abortions have a "competitive advantage" on the dating circuit, since they can offer sex at a lower expected price. Women who are unwilling to have an abortion are either at a disadvantage or must reduce their expectations that the man will help out in the event of an unplanned pregnancy. (In other words, unmarried women are less able to demand marriage and support in exchange for sex.) And yes, the world seems very fucked up when it's looked at in this way. Also, Sonia Oreffice found that married women increase their relative bargaining power, since they have more control over their own fertility.