Do we have Roe v Wade to thank for the drop in crime?

That's what economist Steven Levitt proposes in his book, Freakonomics. He analyzed causes usually attributed to the drop in crime since the 1990's -- gun control, aging of the population, tipping point policing and a stronger economy and increased imprisonment rates, only to discover they could account for perhaps only 40% of the crime rate drop. The balance he proposes can be explained only by the availability of abortion. The crime rate started to drop just as the first cohort of post-Row children were reaching their peak age for crime activity. Since many of the women taking advantage of more liberal abortion laws were unmarried, poor and in their teens, whose children would have been most likely to resort to crime, Levitt concludes that an unintended consequence of Roe v Wade was a drop in crime.