Steven Levitt & Stephen Dubner – Freakonomics (2005)
And the millions of women most likely to have an abortion in the wake of Roe v. Wade–poor, unmarried, and teenage mothers for whom illegal abortions had been too expensive or too hard to get–were often models of adversity. They were the very women whose children, if born, would have been much more likely than average to become criminals. But because of Roe v. Wade, these children weren’t being born. This powerful cause would have a drastic, distant effect: years later, just as these unborn children would have entered their criminal primes, the rate of crime began to plummet.
(There’s a chapter largely devoted to this topic in the book, including ways they checked that other causes weren’t overriding whatever effect Roe v. Wade had. Choices have consequences. This one’s interesting and quite possibly disconcerting.)