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February 5, 2007
by Michael J. New, Ph.D.
Center for Data Analysis Report #07-01

The reduction in the incidence of abortion during the 1990s became a topic of much discussion dur­ing the 2004 presidential election. Between 1990 and 1999, the number of reported legal abortions declined by 18.4 percent.[1] Some commentators noted that this decline took place during the Administration of President Bill Clinton, who supported abortion rights and argued that "pro-life"[2] voters receive little tangible benefit from electing Presidents who oppose abortion.[3] Others argued that these reductions were made possible partly by legislation passed by pro-life legislators and upheld by judges appointed by pro-life Presidents.[4]

Despite attention to the reduced overall abortion rate, the more dramatic decrease in the incidence of abortion among minors has received relatively little discussion.

In 1985, 13.5 abortions were performed on minors for every 1,000 girls between the ages of 13 and 17. By 1999, the abortion rate for minors had fallen by over 50 percent to 6.5 per 1,000 teen­age girls ages 13 to 17.[5]

Several factors may explain this decline in the incidence of abortion among minors. First, a stron­ger economy has been shown to reduce the inci­dence of abortion among adults[6] and may have had a similar impact on minors. Second, several studies have found that during the 1990s, teenagers became more likely to delay sexual activity and to abstain from sex altogether.[7] Third, pro-life legisla­tion enacted during the 1990s, particularly parental involvement laws intended to influence minors, were effective in reducing abortion.

This analysis explores the third explanation. The regression results indicate that certain types of pro-life legislation are correlated with reductions in the incidence of abortion among minors:

Parental involvement laws reduced the minor abortion rate by an average of 1.67 abortions per 1,000 females between the ages of 13 and 17.

Medicaid funding restrictions reduced the minor abortion rate by an average of 2.34 abortions per 1,000 females between the ages of 13 and 17.

The results of two natural experiments indicate that pro-life legislation, not changing values, is responsible for the declines in abortion.

Pro-Life Legislation

The 1990s witnessed a substantial increase in the amount of pro-life legislation passed at the state level. In 1992, only 20 states enforced parental involvement statutes.[8] By 2000, 32 states enforced such laws.[9] Since parental involvement laws require minors to notify or to receive permission from a par­ent before having an abortion, these laws could have an especially large impact on the childbearing decisions of minors.

Other types of pro-life legislation gained support during the 1990s as well. In 1992, virtually no states had informed consent laws.[10] By 2000, con­sent laws were in effect in 27 states.[11] Similarly, in 1992, no states had banned or restricted partial birth abortion. By 2000, 12 states had passed bans or restrictions on partial birth abortion.[12]

What prompted this substantial increase in state pro-life legislation? There are two probable explanations.

First, pro-life legislation received increased legal support during the 1990s. Although parental involvement laws predated Roe v. Wade,[13] they were struck down in many cases by state and federal courts in the subsequent decades. In the 1990s, this trend halted as conservative jurists appointed by President Ronald Reagan and President George H. W. Bush gave these laws a better chance to withstand judicial scrutiny. In addition, in Planned Parenthood of Southeastern Pennsylvania v. Casey, [14] the Supreme Court abandoned its trimester framework in favor of a doctrine of "undue burden," which gave parental involvement laws and other types of pro-life legisla­tion broader constitutional protection.

Second, pro-life legislators made considerable and lasting gains at the state level during the 1990s. In 1994, Republicans obtained majority control of both chambers of 11 additional state legislatures. The number of states where Republicans controlled both chambers of the state legislature increased from six in 1990 to 18 in 2000.[15] As Republicans are generally more supportive of pro-life legislation than are their Democratic counterparts, their gains in state legislatures during the 1990s led to the enactment of more pro-life legislation.

Other Research

Research provides a few insights into the impact that increased pro-life legislation has had on the incidence of abortion among minors. Much of the academic literature that examines the incidence of abortion among minors focuses on parental involvement legislation. The findings suggest that parental involvement statutes reduce the number of abortions performed on minors within the bor­ders of a given state.[16] However, researchers are divided over whether these laws reduce the overall number of abortions, in part because minors can circumvent abortion laws in their own states by obtaining abortions in neighboring states that have more permissive laws.

In analyzing the impact of Missouri's parental consent law, Charlotte Ellertson found that the minor abortion rate decreased in Missouri after pas­sage of the law, but she also found that minors were more likely to travel to other states to obtain abor­tions.[17] Ellertson then posited that the increase in out-of-state abortions could be large enough to completely offset Missouri's reduction in the level of in-state abortions.[18]

In contrast, Virginia Cartoof and Lorraine Kler­man found that the number of abortions performed on Massachusetts minors, both in state and out of state, fell by 15 percent after passage of Massachu­setts' parental consent statute.[19] Similarly, several studies analyzing Minnesota's parental notification law have found little evidence that minors are leav­ing the state in significant numbers to obtain abor­tions in neighboring states.[20]

Although many of these studies are insightful, several shortcomings are prevalent within this aca­demic literature.

First, many studies are limited in scope, examin­ing only a small number of states that have enacted these policies[21] or considering data from only a rel­atively narrow range of years.[22]

Second, many studies focus on parental involve­ment laws, which are intended to influence young peo

ple. Yet the literature has largely ignored the impact of other types of pro-life legislation–public funding restrictions, informed consent statutes, and partial birth abortion bans–on abortion rates, a subject that likewise merits rigorous examination.

Third, many studies fail to correct for endogeneity problems. The enactment of pro-life legislation does not occur randomly. Unobserved influences, such as changes in prevailing social values and mores, may also be at work. Indeed, the states that are enacting pro-life laws could be the states that are becoming more religious or more conservative. Changing values and mores, not the legislation per se, may be responsible for the declines in the inci­dence of abortion. However, the academic literature to date does not seriously address these problems.

In the following analysis, I attempt to address these shortcomings. I collect data on abortion rates among minors in every state where data are available from 1985 to 1999. While I examine the impact of parental involvement laws, I also consider the impact of other pro-life policies, including public funding restric­tions, informed consent laws, and partial birth abor­tion bans. Finally, I resolve the endogeneity issue by conducting two natural experiments.


To test for the impact of pro-life legislation on the incidence of abortion among minors, multiregres­sion analysis is performed on a dataset that includes abortion data from nearly every state between 1985 and 1999.[23] Regres­sion analysis is well suited to this type of empirical research because it allows us to examine a number of fac­tors that simultaneously affect state-level abortion rates.

The dependent variable is the abor­tion rate among minors (minor abor­tion rate), a good indicator of pro-life legislation's impact among minors. Specifically, this variable measures the number of abortions that are per­formed on females under the age of 17 per 1,000 females between the ages of 13 and 17. Because this statistic is not published, I calculated it using aggregate gender and age state popu­lation data from the U.S. Census Bu­reau and annual state data on the number of abortions performed on 17-year-olds, 16-year-olds, 15-year-olds, and minors under the age of 15 from the Cen­ters for Disease Control and Prevention (CDC).

To estimate the predicted effect of pro-life legisla­tion, a number of economic and demographic fac­tors are held constant in the analysis. To capture the economy's impact, I include each state's per capita personal income growth in the regression model. A series of variables measuring the racial composition of females between age 13 and age 17 in each state is also included in the model.

Four binary covariates indicate the individual presence or absence of four key state-level pro-life policies:

A parental involvement requirement,
Medicaid funding restrictions,
An informed consent law, and
A partial birth abortion ban.

Parental involvement rules require minors to notify or to receive consent from one or both parents before receiving an abortion.[24]

Medicaid funding restrictions are state restrictions on the use of Medic­aid funding for abortions deemed to be therapeutic in nature. Most states allow use of Medicaid funds for abortions when the pregnancy is the result of rape or termination is necessary to preserve the life of the mother, but state funding regulations differ in regard to abortions defined as therapeutic.

Informed consent statutes, which received constitutional pro­tection in the Supreme Court's 1992 Casey decision, require women seeking abortions to receive addi­tional information about the abortion procedure, which may include information on fetal develop­ment, health risks involved with obtaining an abor­tion, or public and private sources of support for single mothers. The specifics of informed consent laws vary from state to state.

Partial birth abortion bans were upheld in 12 states between 1996 and 2000, although the Supreme Court struck down all partial birth abortion bans in Stenberg v. Carhart in 2000.[25]

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Although the decline in the overall incidence of abortion during the 1990s has been widely reported, scant attention has been paid to the more dramatic reduction in abortion rates among minors. Between 1985 and 1999, the minor abortion rate fell by almost 50 percent, compared to a 29 percent decline in the overall abortion rate. While a number of factors may have contributed to this decline, the impact of pro-life legislation on the incidence of abortion among minors cannot be overlooked.

Specifically, the passage of a parental involvement law correlates with a 16 percent decline in the minor abortion rate, and the passage of Medicaid funding restrictions correlates with a 23 percent decline in the minor abortion rate…

Among minors aged 13 to 17, the abortion rate fell from 13.5 per 1,000 girls in 1985, to 6.5 per 1,000 in 1999, a reduction of over 50%.

The Supreme Court’s Casey decision and the electoral success of pro-life candidates at the state level resulted in a dramatic increase in the number of laws enacted to protect the unborn during the 1990s.  By the end of the decade, more states had adopted pro-life legislation, including parental involvement requirements. 

Regression results from this analysis suggest that parental involvement laws and public funding restrictions are effective in reducing the incidence of abortion among minors. The results indicate that enforced laws were significantly more effective than nullified laws in reducing the abortion rate. 

Moreover, the regression results indicate that parental involvement laws were considerably more effective in reducing the abortion rate for minors than they were for reducing the overall abortion rate.

(Michael J. New, “Analyzing the effect of state legislation on the incidence of abortion among minors; a report of the Heritage Center for Data Analysis.”   Washington, DC, February 5, 2007 (CDA07-01).             &n



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Michael J. New, Ph.D., is an Assistant Professor of Political Science at the University of Alabama, writing for the Heritage Foundation, Washington, D.C., analyzed the effect of state legislation on the incidence of abortion among minors.