Analyzing the Effects of State Legislation on the Incidence of Abortion During the 1990s
by Michael J. New, Ph.D.
Center for Data Analysis Report #04-01
January 21, 2004
The 1990s saw both the election and re-election of a "pro-choice" President.1 However, the "pro-life" movement made considerable gains at the state and local levels.
Survey data indicate that by the end of the decade, more people supported restrictions on abortion and fewer supported discretionary abortion.2
Meanwhile, the actual number of abortions declined during the decade.
For the 46 states reporting data to the Centers for Disease Control and Prevention in both 1990 and 1999,3 the number of abortions fell from 1,035,5734 to 854,416,5 a decline of 17.4 percent. This decline translates into a reduction in the abortion rate from 20.61 to 16.62 abortions per 1,000 women between the
ages of 15 and 44.6
What is the reason for this decline in the number of abortions? The economy, which grew at a brisk rate during the mid- to late 1990s, might be partly responsible.
Studies indicate that abortion rates decline during periods of strong economic growth.7
However, an even more directly related factor might be the impact of legislation intended to reduce the number of abortions.
This study used data from the Centers for Disease Control and Prevention (CDC) and the Alan Guttmacher Institute (AGI) to estimate how state-level "pro-life" legislation affected abortion rates and ratios.8
This paper reports a number of findings based on these data.
Among them:
Those states that adopted pro-life legislation during the 1990s experienced larger reductions in abortion rates and ratios than those states that did not adopt
such legislation.
State laws restricting the use of Medicaid funds in paying for abortions reduced the abortion rate by 29.66 and the abortion ratio by 2.08.
The CDC data indicate that states that adopted informed consent laws saw the abortion ratio drop by 11.69 and the abortion rate by 0.92.
When AGI data are used, statistical analysis indicates that informed consent laws have an even greater effect, reducing the abortion ratio by 22.46 and the abortion rate by 1.57.
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…
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…
Data Sources
The following states did not report data to
the Centers for Disease Control and
Prevention in 1998 and 1999: Alaska,
California, New Hampshire, and Oregon.
Data from Alaska are omitted because of
data collection problems. Data from
Kansas are omitted as well. According to
the 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 in neighboring
states. Instead, it appears that a large
number of women seeking abortions
choose to travel to Kansas. Indeed, for
every year between 1992 and 1999, the
CDC reports that over 40 percent of the
abortions in Kansas are performed on
out-of-state residents. This is by far the
highest figure for an
y state.
Nearly all states reported abortion data to
the CDC through their central health
agency. However some state data were
obtained from hospitals and other medical
facilities. Since these differences in
reporting may bias the results, data from
the following states and years are omitted
from CDC models:
Alabama 1981-1990
Iowa 1981-1997
New Hampshire 1981-1997
West Virginia 1981-1998
Illinois 1984-1987
Kentucky 1984-1986
Oklahoma 1984-1997
The Alan Guttmacher Institute released
state abortion data in the following eight
years: 1985, 1987, 1988, 1991, 1992,
1995, 1996, and 2000. Data from Alaska
are omitted because of data collection
problems. Data from Kansas are omitted
because of the same outlier problems
described above.
1. Legislation intended to reduce legal
barriers to abortion and those who support
such legislation are often referred to as
"pro-choice," while legislation intended to
reduce the number of abortions and those
who support such legislation are often
called "pro-life." These widely accepted
terms are used throughout this study.
2. Lydia Saad, "Public Opinion About
Abortion, An In-Depth Review," Gallup Poll
Special Report, at
www.gallup.com/poll/specialreports/pollS
ummaries/sr020122.asp.
3. Alaska, California, New Hampshire, and
Oregon did not report data in 1999.
4. Centers for Disease Control and
Prevention, Morbidity and Mortality Weekly
Report, December 17, 1993, Vol. 42, pp.
34-35. Calculations by author.
5. Laurie D. 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,
November 29, 2002, at
www.cdc.gov/mmwr/preview/mmwrhtml
/ss5109a1.htm. Calculation by author.
6. The abortion rate is the number of
abortions per 1,000 women between the
ages of 15 and 44.
7. See Rebecca Blank, Christine George,
and Rebecca London, "State Abortion
Rates: The Impact of Policies Providers,
Politics, Demographics, and Economic
Environment," Journal of Health Economics,
Vol. 15 (1996), pp. 513-553.
8. The abortion ratio is the number of
abortions per 1,000 live births.
9. Prior to 1992, courts struck down most
informed consent laws; however, a few
fairly weak laws remained in effect.
10. NARAL Foundation, Who Decides?
1992, p. 9.
11. NARAL Foundation, Who Decides?
2000, p. 125.
12. Ibid.
13. NARAL Foundation, Who Decides?
1992, p. 125.
14. NARAL Foundation, Who Decides?
2000, p. 125.
15. Bureau of the Census, Statistical
Abstract of the United States: 2001
(Washington, D.C.: U.S. Government
Printing Office, 2000), p. 249.
16. Ibid.
17. NARAL Foundation, Who Decides?
2001, pp. 262-263.
18. Deborah Haas-Wilson, "The Impact of
State Abortion Restrictions on Minors'
Demand for Abortions," The Journal of
Human Resources, Vol. 31, No. 1 (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 (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 Blank,
Christine George, and Rebecca London,
"State Abortion Rates: The Impact of
Policies Providers, Politics, Demographics,
and Economic Environment," National
Bureau of Economic Research Working
Paper No. 4853, 1994; and Robert
Ohsfeldt and Stephan Gohman, "Do
Parental Involvement Laws Reduce
Adolescent Abortion Rates?"
Contemporary Economic Policy, Vol. 12, No.
2 (1994), pp. 65-76.
19. Charlotte Ellertson, "Mandatory
Parental Involvement in Minors' Abortions:
Effects of the Laws in Minnesota, Missouri,
and Indiana," American Journal of Public
Health, Vol. 87, No. 8 (1997), pp.
1367-1374.
20. Ibid., p. 1373.
21. Ibid.
22. Ibid., pp. 1371-1372.
23. Stanley K. Henshaw, "The Impact of
Requirements for Parental Consent on
Minor's Abortions in Mississippi," Family
Planning Perspectives, Vol. 27, No. 3
(1995), pp. 120-122.
24. Patricia Donovan, "Judging Teenagers:
How Minors Fare When They Seek Court
Authorized Abortions," Family Planning
Perspectives, Vol. 15, No. 6 (1983), pp.
259-267; Robert Blum, Michael Resnick,
and Trisha Stark, "The Impact of a Parental
Notification Law on Adolescent Abortion
Decision Making," American Journal of
Public Health, Vol. 77, No. 5 (1987), pp.
619-620.
25. Rebecca Blank, Christine George, and
Rebecca London, "State Abortion Rates:
The Impact of Policies Providers, Politics,
Demographics, and Economic
Environment," Journal of Health Economics,
Vol. 15 (1996), pp. 513-553; Anita
Prichard and Sharon Kay Parsons, "The
Effects of State Abortion Policies on States'
Abortion Rates," State and Local
Government Review, Vol. 31, No. 1 (1999),
pp. 43-52.
26. The Alan Guttmacher Institute, named
for a former president of Planned
Parenthood, is a nonprofit organization
focused on sexual and reproductive health
research. Its mission includes the
advancement of reproductive rights.
27. Virginia Cartoof and Lorraine Klerman,
"Parental Consent for Abortion: Impact of
the Massachusetts Law," American Journal
of Public Health, Vol. 76, No. 4 (1986), pp.
397-400; Patricia Donovan, "Judging
Teenagers: How Minors Fare When They
Seek Court Authorized Abortions," Family
Planning Perspectives, Vol. 15, No. 6
(1983), pp. 259-267; Robert Blum,
Michael Resnick, and Trisha Stark, "The
Impact of a Parental Notification Law on
Adolescent Abortion Decision Making,"
American Journal of Public Health, Vol. 77,
No. 5 (1987), pp. 619-620; James Rogers,
Robert Boruch, George Storms, and
Dorothy DeMoya, "
Impact of the Minnesota
Parental Notification Law on Abortion and
Birth," American Journal of Public Health,
Vol. 81, No. 3 (1991), pp. 294-298.
28. 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 (1993), pp.
498-511.
29. For the purposes of this study, women
of childbearing age are defined as those
women between the ages of 15 and 44.
30. Both parental consent and parental
notification statutes are considered
parental involvement requirements.
31. A fixed effect model allows examination
of the within-state effects of pro-life
legislation. By holding the individual states
constant, the regression compares the
abortion rate after legislation was passed
to the abortion rate before legislation was
passed and determines whether the
differences are statistically significant.
32. The regression models that use AGI
data predict that partial-birth abortion bans
result in much larger reductions in
abortion rates and ratios than are
predicted by the regression models that
use CDC data. This is likely because the AGI
data consist of only one year (2000) during
which partial-birth abortion bans were in
effect. As a result, it is possible that the
partial-birth abortion ban variable is picking
up reductions caused by unaccounted for
factors or random effects. Conversely, the
CDC dataset includes data from three
years where states had enacted
partial-birth abortion bans (1997, 1998,
1999). Since the CDC dataset contains
more years, it is believed that their
prediction about the impact of partial-birth
abortion bans is more accurate.
33. a variable is statistically significant if
there is at least a 90 percent certainty that
the given variable has a non-zero effect on
abortion rates or abortion ratios
34. NARAL Foundation, Who Decides?
1992, pp. 125-127, and Who Decides?
2000, pp. 125-127.
35. NARAL Foundation, Who Decides?
1991-2000.
36. Elam-Evans et al., "Abortion
Surveillance."
37. Centers for Disease Control and
Prevention, Morbidity and Mortality Weekly
Report, December 17, 1993, pp. 34-35,
and Elam-Evans et al., "Abortion
Surveillance." Calculation by author.
38. NARAL Foundation, Who Decides?
1992, pp. 125-127, and Who Decides?
2000, pp. 125-127.
[by Michael J. New, Ph.D.
Center for Data Analysis Report #04-01
January 21, 2004]