During the 2004 election,
there was a substantial amount of discussion about whether or not
"pro-life" legislation effectively reduces the
incidence of abortion. Some religious leaders and political
commentators urged pro-life voters to consider issues besides
abortion when voting. Most of them argued that there is little that
elected officials can do to stop abortion through legislation, or
that the pro-life movement has not reaped any real benefits from
supporting candidates who oppose abortion, and that voters
therefore should place greater emphasis on other issues.
It is true that the
pro-life movement has not been successful in overturning Roe v.
Wade. However, the pro-life movement's success at the state
level, especially during the 1990s, is often overlooked.
During the 1990s, the amount of state pro-life legislation
that was passed increased substantially. Furthermore, the number of
abortions performed dropped by around 18 percent during the
However, correlation is
not the same thing as causation. Other factors besides legislation
could have contributed to this decline. So what impact has all of
this legislation had? There is a fair amount of academic and policy
literature that has examined the impact of pro-life legislation at
the state level. Many studies have found that different types of
pro-life legislation have been effective in reducing the number of
abortions in a given state.
shortcoming that is common to all of these studies is that pro-life
legislation is not a random occurrence. It is possible that the
states that are passing pro-life legislation are also the states
that are becoming more conservative or religious. Indeed, these
changes in values and mores, not the legislation itself, might be
responsible for these abortion declines. This potentially
biases the findings of these academic and policy
Social scientists refer to
such problems as "endogeneity problems." Since running
randomized experiments is usually not practical for social
scientists, resolving these problems is often difficult.
However, pro-life laws that have been passed by legislatures
and subsequently nullified by state judiciaries present
researchers with a unique opportunity to resolve these endogeneity
These nullified laws
create a nice set of natural experiments. Presumably, all states
that pass pro-life legislation are undergoing similar changes in
values and mores. However, in some states, the legislation
took effect (enacted-legislation states), and in other states, the
legislation was nullified (nullified-legislation states).
Comparing nullified-legislation states to enacted-legislation
states effectively holds constant any changes in values or mores
and provides better insights into the effectiveness of pro-life
Overall, this research
finds that value shifts have little impact on the incidence of
abortion. Conversely, enacted legislation results in
statistically significant reductions in abortion rates and ratios.
This provides even more evidence that state pro-life legislation
has been effective in reducing the number of abortions in a
given state. Furthermore, it provides additional support for the
idea that pro-life legislation was partly responsible for the
substantial decreases in abortion rates and ratios during
During the 1990s, there
was a substantial amount of pro-life activity at the state level.
In 1992, virtually no
states were enforcing informed consent laws. By 2000,
27 states had informed consent laws in effect.
In 1992, no states had banned or
restricted partial-birth abortion. By 2000, 12 states had bans
or restrictions in effect.
In 1992, only 20 states were
enforcing parental involvement statutes. By 2000, 32 states
were enforcing these laws.
What impact has all of
this legislation had? Much of the academic literature that examines
the impact of state abortion policy focuses on parental
involvement legislation and the extent to which states fund
abortion through Medicaid. Most of these studies argue that
parental involvement laws and restrictions on Medicaid funding
reduce the number of abortions that take place within the
boundaries of a given state.
More recently, I published
a more comprehensive study examining the impact of a wider
range of legislation, including informed consent laws and bans on
partial-birth abortion. This study analyzed data from 49 states
over a span of 15 years and held constant a variety of economic and
demographic variables. All four types of pro-life legislation that
I analyzed-partial-birth abortion bans, parental involvement laws,
informed consent requirements, and public funding restrictions-were
correlated with reductions in the incidence of abortion. In
particular, public funding restrictions and informed consent laws
had the largest and most statistically significant impact.
Indeed, the bulk of the
academic and policy literature indicates that the passage of state
pro-life legislation is associated with a decline in abortion
rates and ratios. However, some observers might question whether
the legislation is actually causing these declines. The
enactment of pro-life legislation is not a random occurrence.
Indeed, it is possible that the states that are passing this
type of legislation are also the states that are becoming more
religious or conservative and that these shifts in values, not the
legislation itself, are causing the abortion
Resolving these sorts of
endogeneity problems is often difficult for social scientists.
Generally speaking, unlike researchers in the hard sciences,
social scientists cannot test their theories through
experimentation. Instead, social scientists must observe
social phenomena and make the best inferences that they
However, in this case,
these endogeneity problems can be resolved through a nice set
of natural experiments. In many states, legislators have passed
pro-life legislation only to have it subsequently nullified by
the judiciary. If the passage of pro-life legislation reflects a
shift in values, then it seems reasonable to assume that all of the
states that passed pro-life legislation experienced a similar
shift in values. However, in some states, the legislation took
effect, whereas in other states, it was nullified by the
If value shifts are
responsible for the abortion declines, then abortion declines in
enacted-legislation states should be similar to declines in
nullified-legislation states. However, if the legislation is
having an effect, then enacted-legislation states would have
significantly larger abortion declines than
nullified-legislation states. Therefore, comparing the
declines in enacted-legislation states with declines in
nullified-legislation states can provide further insights into the
effectiveness of pro-life legislation.
In recent years, there
have been at least six occasions when judges have blocked or
delayed the enactment of parental consent laws (see Table 3) and at
least two occasions when judicial rulings prevented informed
consent laws from going into effect (see Table 4). By
running a series of regressions, it was possible to compare the
impact of enacted legislation to the impact of nullified
nullified-legislation states to enacted-legislation states involves
a regression analysis on a dataset that includes abortion data from
nearly every state between the years of 1985 and 1999. Regression
analysis is well suited to this type of research because it allows
simultaneous examination of various factors' effects on the
number of abortions in each state.
Separate regressions were
run on a pair of dependent variables that measure the number of
abortions in each state. The first dependent variable measures
the state abortion ratio: the number of abortions per 1,000 births.
The second set of dependent variables measure the state abortion
rate: the number of abortions per 1,000 women between the ages of
15 and 44. Data on both the abortion rate and the abortion
ratio were obtained from the Centers for Disease Control and
A variety of
economic and demographic factors were held constant. To capture the
impact of the economy, each state's annual per capita personal
income growth was included in the regression model. Three separate
variables measured the percentage of women of childbearing
age between the ages of 15 to 19,
20 to 25, and 25 to 29. Younger women facing unexpected pregnancies
were hypothesized to be more likely to seek abortions than their
older counterparts. As a result, holding other factors constant,
relatively higher percentages of younger women would be likely to
lead to increases in both abortion rates and abortion ratios. In
addition, a series of variables measuring the racial composition of
women between the ages of 15 and 44 in each state were also
included in the model.
Finally, a fertility
variable measuring the number of births per thousand women between
the ages of 15 and 44 was included in the model. This variable
served as a proxy for the number of pregnancies that occurred.
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
To examine the impact of
different types of state policies that deal directly with access to
abortion, four separate variables were included in the
regression analysis to indicate the presence or absence of
each of four policies.
First is the presence of a
parental involvement requirement. Parental
involvement requirements require minors to notify or receive
consent from one or both parents before receiving an
Second is whether or not a state
restricts Medicaid funding of therapeutic abortions. 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 abortions that are therapeutic in
Third is whether or not a state
has an informed consent statute. Informed consent statutes differ
from state to state, but they all require women seeking
abortions to receive information about the abortion procedure. This
can include information about fetal development, any health risks
involved with obtaining an abortion, or public and private support
for single mothers.
Fourth is whether a state has a
ban on partial-birth abortions. The Supreme Court struck down all
partial-birth abortion bans in Stenberg v. Carhart in 2000.
However, partial-birth abortion bans were upheld in 12 states
between 1996 and 2000.
Table 3 gives a list of
the data sources used.
Finally, to examine the
impact of nullified legislation, two additional independent
variables were added. The first independent variable indicated
states where the judiciary nullified a parental involvement law.
The second independent variable indicated states where the
judiciary nullified an informed consent law. By comparing
enacted-legislation states to the nullified-legislation
states, better insights can be obtained into the impact of pro-life
The regression analysis
uses a fixed effects model in which separate
indicator variables are included for every state and year. The
complete regression results are in Appendix A. The comparisons
between the nullified and the enacted legislation are in Table 4
and Table 5.
Overall, the findings
indicate that enacted legislation has a much larger impact than
value shifts correlated with the passage of legislation.
Furthermore, the difference between enacted-legislation states and
nullified-legislation states achieves statistical significance in
each of the two regressions. This provides solid evidence that
legislation, not factors correlated with the passage of the
legislation, caused the decreases in the incidence of
In, particular, Table 4
and Chart 1 show that, when an informed consent law takes effect,
the regression model predicts that the abortion ratio
decreases by 10.34 abortions for every thousand live births and the
abortion rate decreases by 0.86 abortions per thousand women
between the ages of 15 and 44. Nullified-legislation states
experience increases in both the abortion rate and ratio. More
important, the difference between nullified-legislation states
and enacted-legislation states achieves statistical
Similarly, Table 5 and
Chart 1 indicate that when a parental involvement law is enacted,
the abortion rate decreases by 16.37 abortions for every
thousand live births and the abortion rate decreases by 1.15
abortions for every thousand women between the ages of 15 to 44.
Parental involvement laws that are passed by a legislature and then
later nullified by the judiciary result in modest increases in the
abortion rate and a modest decline in the abortion ratio. Once
again, the difference reaches conventional standards of
The full regression
results (see Appendix A) indicate that other types of
legislation, including Medicaid funding restrictions and
partial-birth abortion bans, also result in reductions in the
incidence of abortion. However, in these cases, comparisons between
enacted-legislation states and nullified-legislation states cannot
be drawn because no instance of judicial nullifications of Medicaid
funding restrictions could be identified. Furthermore, since
the judicial nullifications of partial-birth abortion bans took
place in the late 1990s, there are insufficient data to draw proper
However, the results
clearly indicate that value shifts correlated with the passage
of legislation affect the incidence of abortion only marginally.
This means that any outside factors that are correlated with the
passage of pro-life legislation have only a marginal impact on the
number of abortions that occur. It therefore seems likely that the
abortion declines associated with partial-birth abortion bans
and Medicaid funding restrictions were caused by the legislation
itself and not by any outside factors correlated with the passage
of the legislation.
The number of abortions
that were performed increased throughout the 1970s and the 1980s. However, that trend reversed
itself during the 1990s as the number of legal abortions declined
by 18.4 percent between 1990 and 1999.
There are a number of
different reasons for this decline. However, one factor that cannot
be overlooked is the impact of state pro-life legislation. By
the end of the decade, more states had adopted parental involvement
requirements, informed consent requirements, and partial-birth
A number of academic and policy studies find
that there is a correlation between the passage of pro-life
legislation and a reduction in the incidence of abortion. However,
some have argued that changes in values or mores in states that
have passed such legislation may be responsible for these declines.
By comparing the impact in states that enacted legislation to the
impact in states that nullified legislation, this study is able to
resolve some of these endogeneity problems.
This study analyzes six
states where parental involvement laws were nullified and two
states where informed consent laws were nullified. The regression
findings indicate that enacted legislation results in statistically
significant declines in the incidence of abortion, while value
shifts correlated with the passage of legislation have little
impact. This shows with greater certainty that pro-life
legislation has been effective in reducing the number of
abortions that have taken place.
-Michael J. New, Ph.D.,
is Assistant Professor in the Department of Political Science at
the University of Alabama.
on Abortion Data Received from the CDC
Alaska, California, New
Hampshire, and Oregon did not report data to the Centers for
Disease Control and Prevention in 1998 and 1999.
Data from Alaska are
omitted because of data collection problems. Data from Kansas are
omitted as well.
According to CDC data, the
abortion rate jumped an astounding 69 percent between 1991 and
1999, and this cannot be traced to any shifts in economics, policy,
or demographics in Kansas or neighboring states. Instead, it
appears that the presence of a Dr. Tiller, who is one of the few
doctors in the country specializing in late-term
abortions, may be responsible for this increase. Indeed, for
every year between 1992 and 1999, the CDC reports that over 40
percent of the abortions in Kansas were performed on out-of-state
residents. This is by far the highest figure for any
Nearly all states reported
abortion data to the CDC through their central health agencies.
However, some state data were obtained from hospitals and
other medical facilities. Since these differences in reporting may
bias the results, the data from the following states and years are
omitted from the CDC control:
Hampshire ----- 1981-1997
West Virginia -----
intended to reduce the number of abortions and those who support
such legislation are often called "pro-life." This widely accepted
term is used throughout this study.
Stassen, "Pro-Life? Look at the Fruits," The Courier
Journal, October 11, 2004.
Elam-Evans, Lilo T. Strauss, Joy Herndon, Wilda Y. Parker, Sara
Whitehead, and Cynthia J. Berg, "Abortion Surveillance-United
States, 1999," Centers for Disease Control and Prevention
Morbidity and Mortality Weekly Report, Vol. 51 (November 29,
2002), pp. 1-28, at
www.cdc.gov/mmwr/preview/mmwrhtml/ss5109a1.htm (January 11,
2006). Calculation by author.
Haas-Wilson, "The Impact of State Abortion Restrictions on Minors'
Demand for Abortions," The Journal of Human Resources, Vol.
31, No. 1 (Winter 1996), pp. 140-158; Deborah Haas-Wilson, "The
Economic Impact of State Policy Restrictions on Abortion:
Parental Consent and Notification Laws and Medicaid Funding
Restrictions," Journal of Policy Analysis and
Management, Vol. 12, No. 3 (Summer 1993), pp. 498-511; Patricia
Donovan, "Judging Teenagers: How Minors Fare When They Seek Court
Authorized Abortions," Family Planning Perspectives, Vol.
15, No. 6 (1983), pp. 259- 267; Rebecca M. Blank, Christine C.
George, and Rebecca A. London, "State Abortion Rates: The Impact of
Policies Providers, Politics, Demographics, and Economic
Environment," National Bureau of Economic Research Working
Paper No. 4853, September 1994 (subsequently published in the
Journal of Health Economics, Vol. 15 , pp. 513-553);
and Robert Ohsfeldt and Stephan Gohman, "Do Parental Involvement
Laws Reduce Adolescent Abortion Rates?" Contemporary
Economic Policy, Vol. 12, No. 2 (April 1994), pp.
Prior to 1992,
courts struck down most informed consent laws; however, a few
fairly weak laws remained in effect.
Who Decides? 1992, p. 9.
Who Decides? 2000, p. 125.
Who Decides? 1992, p. 125.
Who Decides? 2000, p. 125.
Impact of State Abortion Restrictions on Minors' Demand for
Abortions," pp. 140-158; Haas-Wilson, "The Economic Impact of State
Policy Restrictions on Abortion," pp. 498-511; Donovan, "Judging
Teenagers," pp. 259- 267; Blank et al., "State Abortion
Rates"; and Ohsfeldt and Gohman, "Do Parental Involvement Laws
Reduce Adolescent Abortion Rates?" pp. 65-76.
Michael J. New,
Ph.D., "Analyzing the Effects of State Legislation on the Incidence
of Abortion During the 1990s," Heritage Foundation Center
for Data Analysis Report No. 04-01, January 21, 2004, at
In the original
Heritage Foundation study, the author also examined the impact of
Medicaid funding restrictions and partial-birth abortion bans.
However, the impact of these laws cannot be tested through natural
experiments. This is because the researcher found no instances in
which a state judiciary nullified a Medicaid funding restriction.
Furthermore, while there are some instances of judges nullifying
partial-birth abortion bans, there exist insufficient data to
examine them properly.
In this paper,
women between the ages of 15 and 44 are considered to be of
consent and parental notification statutes are considered parental
A fixed effect
model allows examination of the intrastate effects of pro-life
legislation. By holding the individual states constant, the
regression compares the abortion rate before legislation was passed
to the abortion rate after legislation was passed and determines
whether the differences are statistically significant.
Disease Control and Prevention, Morbidity and Mortality Weekly
Report, Vol. 42 (December 17, 1993), pp. 34- 35, and Elam-Evans
et al., "Abortion Surveillance." Calculation by
Who Decides? 1992, pp. 125-127, and Who Decides?
2000, pp. 125-127.