Background

During the 1990s, there was a substantial amount of pro-life legislative activity at the state level. For instance:

• In 1992,9 virtually no states were enforcing informed consent laws.10 By 2000, 27 states had informed consent laws in effect.11
• In 1992, no states had banned or restricted the procedure widely known as "partial-birth abortion." By 2000, 12 states had bans or restrictions in effect.12
• In 1992, only 20 states were enforcing parental involvement statutes.13 By 2000, 32 states were enforcing these laws.14

Two major factors led to this increase in pro-life legislation.

First, in 1992, the U.S. Supreme Court in Casey v. Planned Parenthood of Southeastern Pennsylvania abandoned its trimester framework in favor of a doctrine of "undue burden." In so doing, the Court found constitutional some of the policies contained in Pennsylvania's Abortion Control Act. While the Supreme Court did not overturn Roe v. Wade, the decision did give pro-life legislators at the state level more freedom to enact laws designed to protect the unborn.

For instance, the only common forms of state-level legislation before the Casey decision that consistently withstood constitutional scrutiny were parental involvement requirements and restrictions on Medicaid funding of abortions. However, Casey gave constitutional protection to informed consent laws. These laws require abortion providers to inform pregnant women about the health risks associated with abortion, the development of their unborn children, and resources for pregnant women and young mothers. Additionally, a number of states passed "partial-birth abortion" bans before the Supreme Court struck down Nebraska's ban in Stenberg v. Carhart in 2000.

Second, pro-life candidates made considerable and lasting gains in state legislatures during the 1990s. While it is well-known that Republicans obtained control of both the U.S. House of Representatives and the U.S. Senate in 1994, the gains they made in the states have received considerably less attention. Republicans obtained majority control in both chambers of 11 additional state legislatures in 1994.15 Overall, the number of states where Republicans controlled both chambers of the state legislature increased from six in 1990 to 18 in 2000.16 In 2001, Republican state party platforms for 48 of 50 states contained planks that supported restrictions on abortion.17

Other Research

What impact has all of this legislation had? Some academic studies provide insights. Much of the academic literature that examines the impact of state abortion policy focuses on parental consent legislation and the extent to which states fund abortion through Medicaid. Most of these studies argue that parental consent statutes and restrictions on Medicaid funding reduce the number of abortions that take place within the boundaries of a given state.18 However, researchers are considerably more divided over whether or not these laws create overall reductions in the number of abortions. This is because it is possible for some people to circumvent these laws by obtaining abortions in other states where the laws are more permissive.

In "Mandatory Parental Involvement in Minors' Abortions: Effects of the Law in Minnesota, Missouri, and Indiana," Charlotte Ellertson, President and Chief Executive Officer of Ibis Reproductive Health, pays special attention to the impact of Missouri's parental consent law.19 She finds that the number of abortions performed on minors decreased in Missouri after the passage of the parental consent law.20 However, she also found that minors were more likely to travel to other states to obtain abortions.21 In the article, Ellertson argues that this increase in travel could be large enough to offset the reduction in the number of abortions in Missouri.22

Conversely, other studies arrive at different conclusions. One study indicates that the number of abortions performed on Mississippi residents, both in state and out of state, declined after the state's parental consent statute was passed.23 Similarly, other studies that have examined Minnesota's parental notification law have found little evidence that minors are leaving the state in great numbers to obtain abortions.24

While these studies shed light on the abortion patterns of the 1990s, many shortcomings exist.

First and foremost, none of the studies examines the impact of "partial-birth abortion" bans or informed consent statutes. Of course, some of the earlier studies examine a time frame where few, if any, states had such laws. However, even some of the later studies neglect to analyze their impact.25

Second, state abortion data come from two sources, the Centers for Disease Control and Prevention and the Alan Guttmacher Institute.26 Most studies are limited because they use only one of these data sources, each of which has shortcomings. The Guttmacher Institute receives its data from surveys of abortion clinics. While its method of data collection is more consistent than the CDC's, the AGI does not collect data every year. Conversely, the CDC does provide annual data, but its data typically come from state health agencies. Since state health agencies often change their methods for collecting and disseminating data, their data may be somewhat less reliable. Finally, many of these studies have a very limited scope, examining only a small number of states that have enacted these policies.27 This can lead to problems of selection bias. Still others consider only data from relatively few years.28 As a result, these studies may not have sufficient data to draw statistically meaningful comparisons.

This analysis attempts to overcome these limitations. It presents data on abortion rates and ratios in every state from 1985 to 1999, using data from both the CDC and the AGI. Furthermore, it takes into account the impact of informed consent laws and "partial-birth abortion" bans. Finally, it holds constant economic and demographic factors that might cause fluctuations in the number of abortions.

Methodology

The empirical test of the effectiveness of pro-life legislation involves a series of regressions on a dataset that includes statistics on abortions for the years 1985 through 2000. Regression analysis is well-suited to this type of research because it simultaneously examines the effects of various factors on the number of abortions in each state.

Separate regressions were run on four dependent variables measuring the number of abortions within a given state. The first set of dependent variables measure the state abortion ratio as indicated by the CDC and Alan Guttmacher Institute, respectively. The abortion ratio measures the number of abortions for every 1,000 births. The second set of dependent variables measure the state abortion rate as indicated by the CDC and AGI. These variables measure the number of abortions per 1,000 women between the ages of 15 and 44. Combined, these four dependent variables should help determine the impact of various forms of pro-life legislation.

A variety of economic and demographic factors are held constant. To capture the impact of the economy, this study includes each state's per capita personal income growth in the regression model. Additionally, a series of state-level variables measuring the racial composition of women between the ages of 15 and 44 are included in the model as well.

Three separate variables measure the percentage of women of childbearing age29 who are between the ages of 15 to 19, 20 to 25, and 25 to 29, respectively. The hypothesis is that younger women facing unexpected pregnancies would be more likely to seek abortions than their older counterparts. As a result, holding other factors constant, relatively higher percentages of younger women would lead to increases in both abortion rates and abortion ratios.

Finally, a fertility variable, measuring the number of births per 1,000 women between the ages of 15 and 44, is included in the model. This variable serves as a proxy for the number of pregnancies that are occurring. Fewer pregnancies would result in fewer abortions. Similarly, if the fertility variable is low, it might indicate that a higher proportion of pregnancies are planned, which would also result in fewer abor-tions.

Of more interest in this study is the effect of different types of state policies that deal di-rectly with access to abortion. The re-gression analysis in-cludes four separate variables indicating the presence or ab-sence of a particular type of policy.

The first of these variables is the presence of a parental involvement requirement.30 Parental notification requirements require minors either to notify or to receive consent from one or both parents before receiving an abortion.

The second policy variable is whether or not a state restricts funding of therapeutic abortions through Medicaid. Most states will fund abortions through Medicaid when the pregnancy is the result of rape. Similarly, most states fund abortions that are necessary to preserve the life of the mother. However, states differ as to whether they fund therapeutic abortions.

Third is whether or not a state has an informed consent statute. In Casey v. Planned Parenthood (1992), the Supreme Court found that informed consent statutes were constitutional. Informed consent statutes differ from state to state. However, they all require women seeking abortions to receive information about the abortion procedure. This can include information about fetal development, the health risks involved with obtaining an abortion, and the public and private sources of support for single mothers.

The fourth and final policy variable is whether a state has a ban on "partial-birth abortions." About 12 states had "partial-birth abortion" bans in effect between 1996 and 2000 before the Supreme Court struck down Nebraska's "partial-birth abortion" ban in Stenberg v. Carhart in 2000.

The regression model used is a fixed effects model,31 in which separate indicator variables are included for every state and year. Table 1 shows the estimated effects of each of the four policies. The complete regression results are in Table 2 in Appendix A.

The figures in Table 1 measure the predicted change in a state's abortion rate or abortion ratio after a particular piece of legislation is passed. For instance, when data from the Centers for Disease Control are used, the regression model predicts that the passage of an informed consent law will lower the state abortion ratio by 11.69 abortions for every 1,000 births and will lower the state abortion rate by 0.92 abortions per 1,000 women between the ages of 15 and 44. When data from the Alan Guttmacher Institute are used, the regression model predicts that the passage of an informed consent law will lower the state abortion ratio by 22.46 abortions for every 1,000 births and will lower the state abortion rate by 1.57 abortions per 1,000 women between the ages of 15 and 44.32

Discussion

Overall, the results from the regression analysis indicate that pro-life legislation has been effective at reducing the incidence of abortion at the state level. In particular, Medicaid funding restrictions appear to be especially effective at reducing the number of abortions. When data from the CDC are used, the model predicts that Medicaid funding restrictions reduce the abortion rate by 29.67 and the abortion ratio by 2.08. Moreover, these results are statistically significant.33 Furthermore, when AGI data are used, the magnitude and significance of these coefficients are similar. Overall, these findings are consistent with much of the academic literature that examines the impact of Medicaid funding restrictions.

Of particular interest is the impact of informed consent laws. These laws are a recent policy innovation, and none of the other academic studies examines their impact. When the CDC data are used, the regression indicates that the passage of an informed consent law reduces the abortion ratio by 11.69 and the abortion rate by 0.92. When AGI data are used, the results indicate that informed consent laws have an even greater effect, reducing the abortion ratio by 22.46 and the abortion rate by 1.57. All of these results are statistically significant. These findings are particularly interesting because over 20 states adopted informed consent laws between 1992 and 1999.34 It seems likely that these laws played an especially large role in the decline in abortions during the 1990s.

Parental involvement laws appear somewhat less effective than the other types of public policies. In all four of the models, the coefficient for the parental involvement laws is negative, which is consistent with expectations. However, while some of the coefficients approach statistical significance, none actually reaches it. It should also be noted that parental involvement laws limit only the ability of minors to have abortions. Examining their impact on minors who undergo abortions, instead of all women who undergo abortions, would be a better test of the effectiveness of such laws. Even so, parental involvement laws do appear to reduce overall abortion rates and ratios, but their impact is less statistically certain than the impact of Medicaid funding restrictions and informed consent laws.

Finally, all the models predict that "partial-birth abortion" bans reduce abortion rates and ratios. In two of the four models, the coefficients do not achieve statistical significance. However, it should be noted that the first "partial-birth abortion" law was not enacted until 1996, and most "partial-birth abortion" bans went into effect in 1997 and 1998.35 As a result, there are relatively few data with which to evaluate their effectiveness.

Conclusion

The number of abortions rose consistently throughout the 1970s and the 1980s.36 However, that trend reversed during the 1990s as the number of legal abortions declined by 17.4 percent between 1990 and 1999.37

There are a number of different reasons for this decline. However, one factor that cannot be overlooked is the impact of pro-life legislation in the states. By the end of the decade, more states had adopted parental involvement requirements, informed consent requirements, and "partial-birth abortion" bans.38 More important, regression results provide evidence that each of these laws was effective at reducing the number of abortions that took place.

Michael J. New, Ph.D., is a post-doctoral fellow at the Harvard-MIT Data Center.

Appendix A: Regression Results

Regression analysis allows examination of the effects of various factors on the central concern of this paper: state-level abortion rates and ratios. Regression analysis sorts out the effects of a single variable by holding constant the effects of all other variables. Appendix A provides the coefficients and standard errors for the various regression models.

The coefficient of the independent variables provides an estimate of how much a one-unit change of the independent variables changes the dependent variable.

For instance, when data from the Centers for Disease Control are used, the regression model predicts that a 1 percentage point increase in state personal income growth will reduce the state abortion ratio by 0.94 abortions per 1,000 live births and will reduce the state's abortion ratio by 0.10 abortions per 1,000 women between the ages of 15 and 44.

Similarly, when CDC data are used, the regression model predicts that the passage of a parental involvement law will lower the state abortion ratio by 7.22 abortions for every 1,000 births and lower the state abortion rate by 0.54 abortions per 1,000 women between the ages of 15 and 44.