El aborto reduce la delincuencia

Extracto de la introducción:

Legalized abortion may lead to reduced crime either through reductions in cohort sizes or
through lower per capita offending rates for affected cohorts. The smaller cohort that results from abortion legalization means that when that cohort reaches the late teens and twenties, there will be fewer young males in their highest-crime years, and thus less crime. More interesting and important is the possibility that children born after abortion legalization may on average have lower subsequent rates of criminality for either of two reasons. First, women who have abortions are those most at risk to give birth to children who would engage in criminal activity. Teenagers, unmarried women, and the economically disadvantaged are all substantially more likely to seek abortions [Levine et al. 1996].
Recent studies have found children born to these mothers to be at higher risk for committing crime in adolescence [Comanor and Phillips 1999]. Gruber et al. [1999], in the paper most similar to ours, document that the early life circumstances of those children on the margin of abortion are difficult along many dimensions: infant mortality, growing up in a single-parent family, and experiencing poverty.
Second, women may use abortion to optimize the timing of childbearing. A given woman?s ability to provide a nurturing environment to a child can fluctuate over time depending on the woman?s age, education, and income, as well as the presence of a father in the child?s life, whether the pregnancy is wanted, and any drug or alcohol abuse both in utero and after the birth. Consequently, legalized abortion provides a woman the opportunity to delay childbearing if the current conditions are suboptimal. Even if lifetime fertility remains constant for all women, children are born into better environments, and future criminality is likely to be reduced. A number of anecdotal empirical facts support the existence and magnitude of the crimereducing impact of abortion. First, we see a broad consistency with the timing of legalization of abortion and the subsequent drop in crime. For example, the peak ages for violent crime are roughly 18-24, and crime starts turning down around 1992, roughly the time at which the first cohort born following Roe v. Wade would hit its criminal prime. Second, as we later demonstrate, the five states that legalized abortion in 1970 saw drops in crime before the other 45 states and the District of Columbia, which did not allow abortions until the Supreme Court decision in 1973.

Third, our more formal analysis shows that higher rates of abortion in a state in the 1970s and early 1980s are strongly linked to lower crime over the period from 1985 to 1997. This finding is true after controlling for a variety of factors that influence crime, such as the level of incarceration, the number of police, and measures of the state?s economic well-being (the unemployment rate, income per capita, and poverty rate). The estimated magnitude of the impact of legalized abortion on crime is large. According to our estimates, as shown on Table II, states with high rates of abortion have experienced a roughly 30 percent drop in crime relative to low-abortion regions since 1985. While one must be cautious in extrapolating our results out of sample, the estimates suggest that legalized abortion can account for about half the observed decline in crime in the United States between 1991 and 1997.

A number of factors lead us to believe that the link between abortion and crime is causal. First, there is no relationship between abortion rates in the mid-1970s and crime changes between 1972 and 1985 (prior to the point when the abortion-affected cohorts have reached the age of significant criminal involvement). Second, virtually all of the abortion-related crime decrease can be attributed to reductions in crime among the cohorts born after abortion legalization. There is little change in crime among older cohorts.

In this section, we explore in detail the theoretical link between legalization of abortion in the
early 1970s and subsequent drops in crime 15 to 20 years later. We identify a number of alternative pathways through which abortion can affect crime. We then generate ?back of the envelope? calculations as to the likely magnitude of the various channels based on previous research findings. The simplest way in which legalized abortion reduces crime is through smaller cohort sizes. When those smaller cohorts reach the high-crime late adolescent years, there are simply fewer people to commit crime. Levine et al. [1996] find that legalization is associated with roughly a 5 percent drop in birth rates. Assuming that the fall in births is a random sample of all births, total crime committed by this cohort would be expected to fall commensurately.

Far more interesting from our perspective is the possibility that abortion has a disproportionate
effect on the births of those who are most at risk of engaging in criminal behavior. To the extent that abortion is more frequent among those parents who are least willing or able to provide a nurturing home environment, as a large and growing body of evidence suggests, the impact of legalized abortion on crime might be far greater than its effect on fertility rates. This is particularly true given that 6 percent of any birth cohort will commit roughly half the crime [Wolfgang et al. 1972; Tracy et al. 1990].

Prior to the legalization of abortion, there was a very strong link between the number of
unwanted births and low maternal education over the period from 1965 through 1970 [Commission on Population Growth and the American Future 1972, p. 98]. Levine et al. [1996] found that the drop in births associated with abortion legalization was not uniform across all groups. They estimated that the drop in births was roughly twice as great for teenage and nonwhite mothers as it was for the non-teen, white population. In the years immediately following Roe v. Wade, data from the Centers for Disease Control indicate that almost one-third of abortions were performed on teenagers [Centers for Disease Control 1994]. Angrist and Evans [1996)] found that while abortion reforms had relatively modest effects on the fertility of white women, ?black women who were exposed to abortion reforms experienced large reductions in teen fertility and teen out-of-wedlock fertility.?

A number of studies have shown that the availability of abortion improves infant outcomes by
reducing the number of low birthweight babies and neonatal mortality [Grossman and Jacobowitz 1981; Corman and Grossman 1985; Joyce 1987; Grossman and Joyce 1990]. Moreover, Gruber et al. [1999, p. 265] conclude that ?the average living circumstances of cohorts born immediately after abortion became legalized improved substantially relative to preceding cohorts.? They go on to note that ?the marginal children who were not born as a result of abortion legalization would have systematically been born into less favorable circumstances if the pregnancies had not been terminated: they would have been 60 percent more likely to live in a single-parent household, 50 percent more likely to live in poverty, 45 percent more likely to be in a household collecting welfare, and 40 percent more likely to die during the first year of life.?

Previous research has found that an adverse family environment is strongly linked to future
criminality. Both Loeber and Stouthamer-Loeber [1986] and Sampson and Laub [1993] present
evidence that a variety of unfavorable parental behaviors (e.g., maternal rejection, erratic/harsh
behavior on the part of parents, lack of parental supervision) are among the best predictors of juvenile delinquency. Raine et al. [1994, 1996] argue that birth complications combined with early maternal rejection predispose boys to violent crime at age 18. Rasanen et al. [1999] find that the risk of violent crime for Finnish males born in 1966 is a function of (in descending order of impact): mother?s low education, teenage mother, single-parent family, mother did not want pregnancy, and mother smoked during pregnancy. It is possible that abortion could reduce the number of children born under all these circumstances: teenagers who have abortions can get more education before they give birth and may delay childbearing until they are married and/or want a child. In addition, women who inadvertently become pregnant may have engaged in behavior such as smoking, drinking, or using drugs that elevate the prospect of future criminality of their offspring.

A number of studies have looked at cases of women, living in jurisdictions in which governmental approval to have an abortion was required, who sought to have an abortion, but were denied the right to do so [David et al. 1988; Posner 1992, p .283]. Dagg [1991] reports that these women overwhelmingly kept their babies, rather than giving them up for adoption, but that they often resented the unwanted children and were far less likely than other mothers to nurture, hold, and breastfeed these children. In an array of studies in Eastern Europe and Scandinavia, Dagg found that the children who were born because their mothers were denied an abortion were substantially more likely to be involved in crime and have poorer life prospects, even when controlling for the income, age, education, and health of the mother. This literature provides strong evidence that unwanted children are likely to be disproportionately involved in criminal activity, which may be the causal pathway from
greater availability of abortion to lower rates of crime.

Evidence from prisoner surveys further reinforces the link between a difficult home environment as a child and later criminality [Beck et al. 1993]. In 1991, 14 percent of prisoners reported growing up with neither parent present and 43 percent reported having only one parent (compared to 3 percent and 24 percent respectively for the overall population). 38 percent of prisoners report that their parents or guardians abused alcohol or drugs; almost one-third of female inmates report being sexually abused before the age of 18.

A. The expected magnitude of the impact of abortion legalization on crime
Before presenting our empirical estimates in the next section, we present ?back of the
envelope? estimates of the plausible magnitude of the impact of legalized abortion on crime. Previous researchers have studied (1) how legalized abortion affects birth rates across different groups, and (2) crime rates across groups. By combining these two sets of estimates, we can obtain a crude prediction of the impact of legalized abortion on crime.

This analysis considers four factors: race, teenage motherhood, unmarried motherhood, and
unwantedness. Beginning with the first three of these factors, we use the 1990 Census to determine the proportion of children in each of the 8 possible demographic categories (e.g. white children born to teenage mothers growing up in a single-parent household, or black children born to non-teenage mothers growing up in two-parent households). We then use the estimates of Levine et al. [1996] to determine what those proportions might have been in the absence of legalized abortion. Using Rasanen et al. [1999] and observed frequencies of crime by race in the United States, we generate categoryspecific crime rates corresponding to each of the eight cells. Combining these crime rates with the change in the number of births in each category due to abortion provides an estimate of the hypothetical reduction in crime. Finally, under the assumption that 75 percent of unwanted births are aborted (this number appears consistent with data from self-reported pregnancy histories), we estimate the contribution to lower crime from fewer unwanted births.14 It is important to note that our calculations below isolate the marginal contribution of race, teenage motherhood, unmarried motherhood, and unwantedness. Thus, when computing the impact of race, we net out any racial differences in those other characteristics in order to avoid double counting.

The results of this exercise for homicide are as follows. All values reported are the hypothetical reduction in total homicides committed by members of a given cohort. Through a purely mechanical relationship, the 5.4 percent overall decline in cohort size post-legalization obtained by Levine et al. [1996] translates into a 5.4 percent reduction in homicide.

Fertility declines for black women are three times greater than for whites (12 percent compared to 4 percent). Given that homicide rates of black youths are roughly nine times higher than those of white youths, racial differences in the fertility effects of abortion are likely to translate into greater homicide reductions. Under the assumption that those black and white births eliminated by legalized abortion would have experienced the average criminal propensities of their respective races, then the predicted reduction in homicide is 8.9 percent. In other words, taking into account differential abortion rates by race raises the predicted impact of abortion legalization on homicide from 5.4 percent to 8.9 percent.15

Teenagers and unwed women experience reductions in fertility of 13 and 7 percent respectively, well above that for non-teenage, married women. Rasanen et al. [1999] finds, after controlling for other characteristics, that having a teenage mother roughly doubles a child?s propensity
to commit crime, as does growing up with a single parent.16 Accounting for these two factors raises the estimated impact of abortion on homicide from 8.9 percent to 12.5 percent.

Adjusting for unwantedness, which more than doubles an individual?s likelihood of crime based
on the estimates of Rasanen et al. [1999], raises the estimates from 12.5 percent to 18.5 percent. The impact of unwantedness is large because abortion rates of unwanted pregnancies are very high, whereas wanted pregnancies are by definition not aborted.

Thus, using past estimates in the literature, we crudely estimate that crime should fall by 18.5
percent in cohorts that have access to legalized abortion. As of 1997, roughly 60 percent of crimes were committed by individuals born after legalized abortion, implying that (thus far) the hypothetical impact of abortion on crime is only 60 percent of the impact on affected cohorts, or about an 11 percent reduction. To the extent that other factors are correlated with both criminal propensities and abortion likelihoods (e.g. poverty, maternal education, religiosity), this rough estimate is likely to understate the true impact.17 Given that the observed declines in crime in the 1990s are 30-40 percent, abortion may be an important factor in explaining the crime drop. In the next section, we present empirical estimates of the impact of abortion on crime that are roughly consistent with these hypothetical calculations.