Abortion and crime: one has an effect on the other, but it may not be the effect you think.(THE NATION)

VIOLENT crime in the United States shot up like a rocket after 1960. From 1960 to 1991, reported violent crime increased by an incredible 372 percent. This disturbing trend was seen across the country, with robbery peaking in 1991 and rape and aggravated assault following in 1992. But then something unexpected happened: Between 1991 and 2000, rates of violent crime and property crime fell sharply, dropping by 33 percent and 30 percent, respectively. Murder rates were stable up to 1991, but then plunged by a steep 44 percent.

Several plausible explanations have been advanced for the drop during the 1990s. Some stress law-enforcement measures, such as higher arrest and conviction rates, longer prison sentences, "broken windows" police strategies, and the death penalty. Others emphasize right-to-carry laws for concealed handguns, a strong economy, or the waning of the crack-cocaine epidemic.

Of all the explanations, perhaps the most controversial is the one that attributes lower crime rates in the '90s to Roe v. Wade, the Supreme Court's 1973 decision to mandate legalized abortion. According to this argument, the large number of women who began having abortions shortly after Roe were most likely unmarried, in their teens, or poor, and their children would have been "unwanted." Children born in these circumstances would have had a higher-than-average likelihood of becoming criminals, and would have entered their teens--their "criminal prime"--in the early 1990s. But because they were aborted, they were not around to make trouble.

This is an attention-grabbing theory, to be sure. But a thorough analysis of abortion and crime statistics leads to the opposite conclusion: that abortion increases crime.

Debate about the relationship between abortion and crime was greatly influenced by a Swedish study published in 1966 by Hans Forssman and Inga Thuwe. They followed the children of 188 women who were denied abortions from 1939 to 1941 at the only hospital in Gothenburg, Sweden. Their study compared these "unwanted" children with another group, this one composed of the first child born at the hospital after each of the "unwanted" children. They found that the "unwanted" children were much more likely to grow up in adverse conditions--for example, with divorced parents, or in foster homes. These children were also more likely to become delinquents and have trouble in school. Unfortunately, the authors never investigated whether the children's "unwantedness" caused their problems, or were simply correlated with them.

Forssman and Thuwe's claim, notwithstanding the limits of the data supporting it, became axiomatic among supporters of legalized abortion. During the 1960s and '70s, before Roe, abortion-rights advocates attributed all sorts of social ills, including crime and mental illness, to "unwanted" children. Weeding these poor, crime-prone people out of the population through abortion was presented as a way to make society safer.

Recently, John Donohue and Steven Levitt--a law professor and an economist, respectively--revived the debate. They presented evidence that supposedly demonstrated abortion's staggeringly large effect on crime rates, and argued that up to "one-half of the overall crime reduction" between 1991 and 1997, and up to 81 percent of the drop in murder rates during that period, was attributable to the rise in abortions in the early to mid 1970s. If that claim was accurate, they had surely found the Holy Grail of crime reduction.