Friday, July 20, 2018

Pro-life laws prevent abortion primarily by preventing unplanned pregnancy.

Today's guest post is by Conner Alford.

Women and their partners are generally forward-thinking and rational in their fertility behavior.

Within our society’s broader debate on abortion, two particular pro-choice arguments have occupied a great deal of attention among political activists and leaders alike. The first and stronger of these arguments postulates that legal restrictions make abortion more dangerous but that they do not make it any less common. The underlying logic here is that pro-life policies simply replace safe, legal terminations with an equal number of dangerous, illegal and self-induced or ‘back-alley’ abortions (AGI 1999, 2009). In other words, if a woman is pregnant and does not want to be, she will not consider the legality of her actions or the risks to her own health when deciding whether or not to abort. Any woman willing to get a safe, legal abortion is also willing to get an unsafe, illegal one. When the former is harder to obtain, she will trade it in for the latter. When the latter is no longer necessary because laws have been liberalized, she will trade it for the former. This is the argument articulated by the Alan Guttmacher Institute[1] (AGI) and its affiliated researchers (Tietze 1973; Juarez et al 2005; Sedgh et al 2007b; Singh et al 2010).

The second argument makes a somewhat contradictory claim. According to this narrative, pro-life policies do in fact mitigate abortions. However, they only do so by replacing those abortions with unwanted births. Women trade abortions for babies. As a result, the story goes, these undesired offspring either wind up in state custody or eventually wash out to become criminals (Levitt and Donahue 2001). Either way, the conclusion that we are supposed to draw is that pro-life policies are generally ill-advised. However, both of these arguments are deeply inconsistent with the empirical record and based on a fundamental misconception about the primary way in which abortion laws actually work and operate.

First, studies have shown that while legal restrictions on abortion do reduce the rate at which it occurs, they do not necessarily result in an increase in the birth rate (Trussel et al. 1980; Matthews et al. 1997). Second, the claim that pro-life policies simply lead to an increase in maternal deaths by driving pregnant women to seek unsafe abortions is directly challenged by the empirical record. The lowest maternal mortality rates (MMR) in Europe, for example, occur in Poland, Malta and Ireland—all of which have extremely restrictive policies (Mundial 2010; Hogan et al. 2010). Further, a plethora of systematic analyses examining countries from around the world continuously challenge the idea that legal restrictions on abortion increase MMRs or hospitalizations.[2]  This, then, undermines a key assumption in the AGI narrative about illegal abortions. Third, it is important to note that within the academic community the debate is, generally speaking, no longer about whether legal restrictions reduce abortions so much as how they manage to do so. That pro-life policies mitigate abortion is a point that has been repeatedly illustrated by literally dozens of independent, peer-reviewed studies over the course of several decades.[3]

There has, however, been some disagreement about the exact causal mechanism responsible for this relationship. Herein we find the chief problem with the two perspectives introduced at the beginning of this essay. Not only are their key assertions inconsistent with the empirical record, their entire arguments are fundamentally oblivious to recent academic insights on how abortion laws actually operate. Traditionally, scholars have tended to assume that such policies function to minimize abortions by acting on the posterior “…decision of a woman who is pregnant not to have the child” (Medoff 1988, p. 354). In other words, the law was presumed to affect a woman’s behavior only after she had already become pregnant. The AGI and other pro-choice advocates have adopted this outdated presupposition.

Since the mid 1990s, however, the academic understanding has evolved in light of new evidence. A substantial number of independent, peer reviewed studies have consistently shown that legal restrictions on abortion work primarily by reducing the rate at which unplanned pregnancies occur in the first place (Kane and Staiger 1996) and only secondarily by influencing the behaviors of women who are already pregnant (Levine 2004a)! In other words, pro-life policies address both the symptom and the cause! To be more specific, research has shown that women and their partners are generally forward-thinking and rational in their fertility behavior. They do not wait until after a pregnancy has already occurred before deciding whether they should take steps to preempt parenthood. As a result, pro-life policies actually help to reduce the unplanned pregnancy rate by incentivizing couples to take additional precautions prior to a potential pregnancy rather than waiting to obtain an abortion after the pregnancy has already occurred. Conversely, the opposite is also true. When abortion is readily accessible, this very availability reduces the incentive to avoid becoming pregnant by offering a sort of ‘insurance policy,’ should you or your partner happen to do so. For example, studies have persistently shown that more permissive policies are causally connected to an increase in unprotected sex whereas more restrictive policies lead to an increase in contraceptive usage (Levine 2004b; Medoff 2008a, b; Felkey and Lybecker 2011, 2014, 2015). There is also some evidence to indicate that legally restricting abortion leads to a change in the overall amount of sexual activity (Alford 2016).

Of course, many readers are likely to find this logic somewhat counterintuitive or even offensive. Despite this, it has been overwhelmingly supported by the empirical record (Kane and Staiger 1996; Levine et al. 1996; Levine 1999, 2002, 2003, 2004; Levine and Staiger 2004; McNabb 2007; Medoff 2008a, b; Felkey and Lybecker 2011). It also helps to explain the previously puzzling findings of several studies which suggested  that abortion laws were able to reduce the number of abortions without an increase in births (Trussel et al. 1980; Matthews et al. 1997) or harming maternal health outcomes (see footnote 3). Furthermore, it is consistent with previous findings that the legalization of abortion is associated with an increase in the spread of sexually transmitted diseases whereas pro-life policies have the opposite impact (Kick and Stratmann 2003; Klick and Neelsen 2012). Studies examining the impact of abortion policies on the number of infants available for adoption have, similarly, supported the hypothesis (Gennetian 1999; Bitler and Zavodny 2002; Medoff 2008b).

In conclusion then, it is important to understand that the primary interaction between pro-life policies and individual fertility decisions happens before a potential pregnancy. Men and women are generally rational, free and forward-thinking when it comes to their sex lives. They consider the risks and potential costs of an unwanted pregnancy before making decisions about whether to engage in sexual activity or to utilize contraception. When those costs are subverted by liberalized abortion laws, this provides a sort of ‘insurance policy,’ which encourages uninhibited sexual activity. When those costs are reinforced by pro-life policies, however, the opposite occurs. Contraceptive usage goes up and unplanned pregnancies go down. As a result, legal limitations on abortion are capable of reducing abortion rates without actually impacting the overall number of births. Where pro-life policies do lead to an increase in births, this change is secondary and relatively modest as compared to the decline in unplanned pregnancy. As a result of this, restrictions on abortion are also able to operate without a concomitant risk of unsafe abortions. After all, you cannot illegally terminate a pregnancy that never occurred. This helps to explain why there does not seem to be any positive relationship between legalized abortion and maternal health outcomes.[4] The arguments introduced at the opening of this essay must, therefore, be dismissed in light of new academic evidence and empirical data. The science simply does not support them. It does, however, indicate that pro-life laws do not merely address abortion as a symptom but that they attack the underlying cause of abortion—unplanned pregnancy—at its source. 

Alan Guttmacher Institute (AGI). 1999. “Sharing Responsibility: Women, Society & Abortion Worldwide.” New York.
__________. 2009. “Abortion Worldwide: A Decade of Uneven Progress.” New York.
Alford, Conner. 2016. "The Economics of Abortion: A Comparative Analysis of Mexico and the United States." Proquest Dissertations. Available at:
Bitler, Marianne and Madeline. Zavodny. 2002. "Did Abortion Legalization Reduce the Number of Unwanted Children? Evidence from Adoptions." Perspectives on Sexual and Reproductive Health. 34(1) 25-33.
Donohue III, John J and Steven D. Levitt. "The Impact of Legalized Abortion on Crime." The Quarterly Journal of Economics. 116(2): 379-420.
Felkey, Amanda J. and Lybecker, Kristina M. 2011. "Variation in Pill Use: Do Abortion Laws Matter?" International Journal of Business and Social Science. 2(16): 1-12.
_____. 2014. “Utilization of Oral Contraception: The Impact of Direct and Indirect Restrictions on Access to Abortion." The Social Science Journal.  51: 44-56.
 _____. 2015. “The Role of Restrictive Abortion Legislation in Explaining Variation in Oral Contraceptive Use.” Clinics in Mother and Child Health. 12(4): 1-10.
Gennetian, Lisa A. 1999.  "The Supply of Infants relinquished for Adoption: Did Access to Abortion Make a Difference?" Economic Inquiry. 37(3): 412-431.
Gober, Patricia. 1994. "Why Abortion Rates Vary: A Geographical Examination of the Supply of and Demand for Abortion Services in the United States in 1988." Annals of the Association of American Geographers. 84: 230-250.
Guldi, Melanie. 2008. "Fertility Effects of Abortion and Birth Control Pill Access for Minors." Demography. 45(4): 817-827.
Haas-Wilson, Deborah. 1993."The Economic Impact of State Restrictions on Abortion: Parental Consent and Notification Laws and Medicaid Funding Restrictions." Journal of Policy Analysis and Management. 12(3): 498-511.
Hansen, Susan B. 1980. “State Implementation of Supreme Court Decisions: Abortion Rates since Roe v. Wade.” The Journal of Politics. 42: pp. 372-395.
Hogan MC, Foreman KJ, Naghavi M, Ahn SY, Wang M, et al. 2010. "Maternal mortality for 181 countries, 1980-2008: a systematic analysis of progress towards Millennium Development Goal 5." Lancet 375(9726): 1609–1623.
Kane, Thomas J. and Douglas Staiger. 1996. "Teen Motherhood and Abortion Access." The Quarterly Journal of Economics. 111(2): 467-506
Koch, Elard Miguel Bravo, Sebastián Gatica, Juan F. Stecher, Paula Aracena, Sergio Valenzuela, IvonneAhlers. 2012A. “Sobrestimacióndel Aborto Inducido en Colombia y otros Países Latino Americanos. [Overestimation of induced abortion in Colombia and other Latin American countries].” Ginecol Obstet Mex. 80(5): 360-372.
Koch, Elard, John Thorp, Miguel Bravo, Sebastian Gatica, Camila X. Romero, Hernan Aguilera, IvonneAhlers. 2012b. "Women's Education Level, Maternal Health Facilities, Abortion Legislation and Maternal Deaths: A Natural Experiment in Chile from 1957 to 2007." PLoS One. 7(5): 1-16.
Koch, Elard, Calhoun, Paula. Aracena, Sebastian Gatica, and Miguel Bravo. 2014. "Women's education level, contraceptive use and maternal mortality estimates." Public Health, 128(4): 384-7.
Koch, Elard, Monique Chireau, Fernando Pliego, Joseph Stanford, Sebastián Haddad, Byron Calhoun, Paula Aracena, Miguel Bravo, SebastiánGatica, and John Thorp. 2015. “Abortion legislation, maternal healthcare, fertility, female literacy, sanitation, violence against women, and maternal deaths: a natural experiment in 32 Mexican states."BMJ. 5(2): e006013–e006013.
Levine, Phillip B., Amy B. Trainor, and David J. Zimmerman. 1996. “The effect of Medicaid abortion funding restrictions on abortions, pregnancies and births.” Journal of  Health Economics. 15: 555-578.
Levine Phillip B., Douglas Staiger, Thomas J. Kane and David J. Zimmerman. 1999. "Roe v. Wade and American Fertility." American Journal of Public Health. 89(2): pp. 199-203.
Levine, Phillip B. 2002. The Impact of Social Policy and Economic Activity throughout the Fertility Decision Tree.” in Risky Behavior among Youths: An Economic Analysis. E.D. Jonathan Gruber. National Bureau of Economic Research, pp. 167-218.
 _____. 2003. “Parental Involvement Laws and Fertility Behavior.” Journal of Health Economics. 22(5): 861–878
_____. 2004a. "Abortion Policy and the Economics of Fertility." Society, 41(4): 79-85.
_____. 2004b. Sex and Consequences: Abortion, Public Policy, and the Economics of Fertility. Princeton, N.J: Princeton University Press.
 Levine, Phillip B. and Douglas Staiger. 2004. "Abortion Policy and Fertility Outcomes: The Eastern European Experience." Journal of Law and Economics. XLVII (April): 223-243.
Matthews, Stephens David Ribar and Mark Wilhelm. 1997."The Effects of Economic Conditions and Access to Reproductive Health Services On State Abortion rates and Birthrates." Family Planning Perspectives. 29(2): 52-60.
McNabb, Leland. 2007. “Public Policies and Private Decisions: An Analysis of the Effects of Abortion Restrictions on Minors’ Contraceptive Behavior.” Available at:
Medoff, H. Marshall. 1988. "An Economic Analysis of the Demand for Abortion." Economic Inquiry. 26: 353-359.
 _____. 2008a. "Abortion costs, sexual behavior, and pregnancy rates." The Social Science Journal. 45: 156-172
. _____. 2008b. “The Effect of Abortion Costs on Adoption.” International Journal of Social Economics. 35(3): 188-201.
Mundial, Banco. 2010. "Trends in Maternal Mortality: 1990 to 2008." Available at:
New, Michael. 2004. "Analyzing the Effects of State Legislation on the Incidence of Abortion During the 1990s."
_____. 2007. “Analyzing the Effect of State Legislation on the Incidence of Abortion Among Minors.”
_____. 2011. “Analyzing the Effect of Anti-Abortion U.S. State Legislation in the Post Casey Era”. State Politics & Policy Quarterly. 11: pp. 28-47.
_____. 2014. “Analyzing the Impact of U.S. Antiabortion Legislation in the Post-Casey Era A Reassessment.” State Politics & Policy Quarterly. 11: pp. 28-47.
Trussell, J., J. Menken, B.L, Lindheimand B. Vaughan. 1980. “The impact of restricting Medicaid financing for abortion.” Family Planning Perspectives 12, 120-130.

[1] The AGI is a pro-choice lobbying organization and the semi-official research division of Planned Parenthood. Its statement of purpose is to promote the liberalization of worldwide abortion laws.
[2] Similarly, in South and Central America, Koch et al (2014) finds no relationship between the restrictiveness of state policies on abortion in Mexico and maternal mortality, while a time series analysis of Chile failed to show any relationship between historical changes in abortion policy and either maternal mortality or abortion related hospitalizations (Koch et al. 2012a). Systematic analyses in Eastern Europe and studies examining the impact of legalized abortion in Mexico City also undermine the AGI narrative (Levine and Staiger 2004; Klick and Neelsen 2012; Koch et al 2012b).
[3] Hansen 1980; Medoff 1988, 2008a, 2008b; Haas-Wilson 1993; Gober 1994; New 2004, 2007, 2011a, b; Guildi 2008; Koch et al. 2012a, b, 2014…the list goes on. 
[4]  In fact, some research indicates the opposite: that more liberal abortion laws may actually lead to an increase in maternal mortality and morbidity (Alford 2016). Although these findings have yet to be fully explained, one possibility is that women who obtain abortions are able to become pregnant again more quickly and/or are more likely to return to former levels of sexual activity. As a result, this leads to an increase in the overall number of pregnancies a woman experiences and therefore her overall risk of experiencing a potentially life threatening complication. This may also help to explain why countries with more restrictive abortion policies in both Latin America and Europe tend to have maternal mortality rates that are lower than the regional average (see above) and why the abortion mortality ratio decrease by almost 96% subsequent to an abortion ban in Chile (Koch 2013).

Tuesday, July 17, 2018

Highlights from Justice4Life webcast

Last night, Students for Life of America hosted a webcast on the topic of its Justice4Life campaign, a grassroots effort to confirm Judge Kavanaugh to the Supreme Court. A recording will be available soon, but in the meantime, here are my notes.

Emcee David Bereit
  • David uses the word "opportunity" constantly. An historic opportunity, an opportunity to restore the right to life as established in the Constitution, an opportunity we've waited for for decades... 
  • He emphasizes Justice Kennedy's swing role; he was "not a vote we could ever count on," although he did vote the right way in NIFLA v. Becerra
Former U.S. Attorney General Ed Meese
  • "For too long, we have had people on the Supreme Court who have ignored what the Constitution actually says." 
  • Religious minorities flocked to the early United States because of our protections for freedom of conscience; preserving that freedom is critical
  • "Throughout his career, [Kavanaugh] has demonstrated his fidelity to the Constitution." 
  • Notes that Federalist Society has vetted nominees, including Gorsuch and Kavanaugh
  • Communicate with your Senators with the goal of seating Kavanaugh before the next term begins on October 1st. True, every Senator won't read every letter/email, but staffers compile reports about the numbers of letters sent. Write letters to the editor of your local paper too! 
  • The effort starts now, as Senators have one-on-one meetings with Kavanaugh.
Ken Klukowski, First Liberty Institute
  • His critical concern is what replacing Kennedy means for First Amendment rights
  • Underlying judicial philosophy matters; result-driven decisions may go your way, but set bad precedents for you next time. We want a Justice who will "embrace democracy" and allow legislators who are accountable to the people to decide most policy questions. 
  • Klukowski takes on criticisms of Kavanaugh's past decisions from non-lawyers. Kavanaugh has been "faithful to his role as a subordinate judge on an inferior court," where he must apply Supreme Court precedent; that doesn't necessarily mean that he agrees with those precedents.
(I missed a significant portion of the webcast here, which I gather was focused on Judge Kavanaugh's qualifications, because I got a phone call. So sorry!)

Marjorie Dannenfelser, SBA List
  • Individual people have ALL the power in America. "We can either use it, or we can let it go by the wayside... This moment is decades in the making. There is no overstating, in my opinion, the moment we are in right now."
  • Recounts President Trump's promise to nominate Scalia-like Justices and submission of a list to the American people before the election
  • Breakdown of the Senate: we have 49 solid pro-life votes, but Sen. McCain is . The two pro-choice Republicans could derail everything, but we can offset them with pro-life Democrats who previously voted for Gorsuch. The pressure on Sens. Donnelly, Heitkamp, and Manchin (and to a lesser extent Sen. Doug Jones of Alabama) is intense. The abortion industry knows what's at stake. "Tier 2" Senators (harder to get, but possble) are McCaskill and Nelson. 
  • "No matter where you live, the most important thing you can do is ensure that the Senate understands the intensity of this moment. ... It has an echo effect, even if you're not in those [swing] states."
  • Students for Life and Susan B. Anthony List have rallies planned for Senators' district offices.
  • Older Senators care about phone calls; younger ones care about tweets; everybody cares about email. 
  • Millions of children can be saved by just a handful of votes.
Kristan Hawkins, Students for Life of America
  • Go to; students can sign up for the national tour happening the first week of August! Anyone, student or not, can download an action kit with information on how to contact your Senator, advice to write/submit a letter to the editor, sample tweets, etc.
  • On Saturday, August 11, there will be rallies throughout the nation. Sign up to be a rally captain (again, at to bring a rally to your community!
  • David chimes in: you don't have to have special skills to be a rally captain. Ordinary people are the agents of change.

Monday, July 16, 2018

Abortion and Disability Rights

Every life has equal worth. However, not all lives are treated with dignity. For instance, society commonly favors the lives of non-disabled people over disabled people. This preference even appears in the debate about the legality of abortions. A common argument pro-choicers pose is that a woman should get an abortion if she is not comfortable bearing and/or raising a child with disabilities. An abortion would be better than birthing an unwanted child into this world, correct? I would argue otherwise.

Financial issues are still prevalent in today’s economy. Admittedly, raising a disabled child does require additional expenses than it would raising a non disabled child. However, abortion should not be posed as the best answer to a parent’s financial troubles. Abortions are a band aid solution to poverty. A better alternative would be improving the safety net for guardians. Perhaps then fewer people would feel it is financially obligatory to terminate pregnancies.

The most discussed disability in the debate is Down Syndrome (DS). Iceland recently announced they have an extremely low percentage of citizens with DS. In the article What kind of society do you want to live in?: Inside the country where Down Syndrome is disappearing, Julian Quinones and Arijeta Lajka from CBS News reported the cause. Icelandic mothers get prenatal screenings and get abortions after finding the child has DS. This is upsetting for various reasons. One justification for abortion is that kids with DS are likelier to get put in and stay in the foster care system; Abortion would end any chance of possible emotional suffering. However, ableism is the underlying issue. People with DS and other disabilities are as valuable as people without disabilities, and should be viewed as such.

The rights of disabled people is close to my heart. I personally have a speaking impediment, which has led to me sometimes being treated differently. I do not want sympathy, but my past has influenced my political beliefs. The existence of disabled people should not be used to justify abortion; our lives have meaning too.

[Today's guest post by Angelica Del Pilar is part of our paid blogging program.]

Friday, July 13, 2018

Happening Sunday...

This Sunday, July 15, is a big day for two reasons:

1. It's the submission deadline for Create|Encounter! The second annual Create|Encounter contest, organized by our friends at Rehumanize International, is home to creative works of all kinds—poetry, narrative fiction, paintings, scripts, music, photography, sculpture, video, you name it—that relate to human rights and freedom from violence. That naturally includes abortion, but since Rehumanize International is a multi-issue group, you can also submit pieces that address war, human trafficking, the death penalty, racism, poverty, and other social ills.

Full submission guidelines can be found here. Winners get free admission to the Rehumanize conference October 12-14 in Pittsburgh, and may be published in the Life Matters Journal! Need inspiration? Check out last year's winners and honorable mentions here.

2. It's my 30th birthday! Yes, birthdays are arbitrary. But I love an excuse to celebrate, and 30 is a nice round number. It also makes me reflect on how I'm a "real adult" in the eyes of all the student pro-life activists who I was one of just a blink of an eye ago, I swear...

If you'd like to do something nice for me on my birthday, I'd love nothing more than a $30 donation to Secular Pro-Life. Help me start a new decade of advocacy on the right foot. Thanks!

Wednesday, July 11, 2018

SBA List Poll: Voters in Key States Want Kavanaugh Confirmed to SCOTUS

In case you've been living under a rock, President Trump nominated Judge Brett Kavanaugh to fill the Supreme Court seat made empty by Justice Kennedy's retirement. Speculation is rampant that Kavanaugh could be the fifth vote necessary to repeal Roe v. Wade—or at the very least, allow states to regulate abortion businesses like the medical facilities they purport to be, which the Court rejected in Whole Woman's Health v. Hellerstedt.

The confirmation process is bound to be nasty and partisan. The GOP currently holds the slimmest of majorities in the Senate. Possible surprises could come from Republican abortion supporters Sen. Murkowski of Alaska and Sen. Collins of Maine, and/or from any of the several Democratic Senators who are up for re-election in red states.

Yesterday, the Susan B. Anthony List released a poll from some of those states. Respondents in Florida (Sen. Nelson), Indiana (Sen. Donnelly), Missouri (Sen. McCaskill), North Dakota (Sen. Heitkamp), and West Virginia (Sen. Manchin) were asked if they wanted their Senators to confirm Trump's then-unnamed nominee. Even without knowing it would be Kavanaugh, who is widely considered a safe pick, strong majorities supported confirmation:
  • 56% in Florida
  • 56% in Indiana
  • 57% in Missouri
  • 68% in North Dakota
  • 59% in West Virginia
The numbers highlight the bind those five Democratic Senators face. Will they follow the will of their constituents by confirming Kavanaugh, and risk displeasing their base? Or will they vote against Kavanaugh and have that vote become the subject of attack ads which will resonate with a majority of voters? Neither is ideal heading into November. 

The pollsters followed up with a fascinating second question: “Do you think that the U.S. Supreme Court should decide abortion policy for [Name of State], or do you think abortion policy should be decided by the people of [Name of State] through their elected officials?” 

This is a great way to ask the question. As many have pointed out, polls that ask whether a person supports or opposes Roe v. Wade are highly problematic. Roe is a complex case that legal scholars have written volumes about; it's unfair to assume that the average person understands it. And when pollsters try to explain Roe's holding as part of the question, they invariably do a bad job. Framing the question in terms of who makes abortion policy is much less confusing. It's not perfect—for one thing, it doesn't account for subsequent cases like Planned Parenthood v. Casey and Gonzalez v. Carhart that gave states a bit more room to legislate—but it beats the alternatives. 

And the answers are quite illuminating. In all five states surveyed, voters much preferred that abortion policy be set by legislatures instead of the Supreme Court: 
  • 54% in Florida
  • 65% in Indiana
  • 57% in Missouri
  • 67% in North Dakota
  • 57% in West Virginia
Those results are great news for the right to life, but we should not take anything for granted. Remember to contact your Senators, especially if you live in one of those key states!

Monday, July 2, 2018

Which decreases abortion rates more: contraception access or abortion restrictions?

Pro-choicers frequently claim that making abortion illegal won't decrease the number of abortions; it will only decrease the number of safe, legal abortions. They suggest that there is no practical use to restricting abortion legally and that if pro-lifers really cared about decreasing abortion rates, they would focus on decreasing unplanned pregnancies (through better access to contraception, better sex education, etc.)

So pro-choicers claim.

But there's a lot of research to show that abortion law affects abortion rates--and not just legal abortion rates, but total abortion rates. Studies often measure the changes in fertility in areas where abortion access recently changed. Secular Pro-Life has compiled a list of such studies if you're interested.

I've now had a few conversations where I point out this reality, and the pro-choice person's response is to claim that even if abortion restrictions have some nonzero effect on abortion rates, that effect is dwarfed by the decrease in abortions thanks to contraception access. It's easy for me to believe that both more access to contraception and less access to abortion will decrease abortion rates, and personally I'm for taking both approaches. But the claim that the effect of contraception access trounces the effect of abortion access sounds like just a slightly watered down version of the false claim that abortion access doesn't affect abortion rates at all. That is, it's an ad hoc, ill-founded claim to justify our country's incredibly liberal abortion laws, but the evidence (at least what I've seen so far) doesn't bear it out.

For example, in late 2017 the Daily Mail published "Abortion rate plummets to an historic low, CDC figures reveal." Specifically the article claims
While the drop mirrors the closure of abortion clinics nationwide, experts say the figure is likely down to more effective use of contraception and the falling pregnancy rate.
The article references this CDC report, which has found a net decrease in the abortion rate (number of abortions per 1,000 women age 15-44) of 22% (from 15.6 to 12.1). This is great news, but it's not clear from the CDC report the extent to which different factors contributed to the decrease. The CDC authors explain
One factor that might have contributed to this decrease is the increase that occurred during the same period in the use of the most effective forms of reversible contraception, specifically intrauterine devices and hormonal implants, which are as effective as sterilization at preventing unintended pregnancy (102–105). Although use of intrauterine devices and implants has increased in recent years, use of these methods remains low in comparison with use of oral contraceptives and condoms, both of which are less effective at preventing pregnancy (102,104).
So contraception likely played a role, but the CDC can't quantify it, and they still find that the most effective forms of contraception are not used much compared to the less effective forms. They certainly aren't asserting that the entire 22% decrease is due solely to contraception access, and their report doesn't attempt to compare the effects of contraception access to the effects of abortion access. 

There are studies that looked at both factors. For example, this Guttmacher report found that between access to the Pill and access to abortion, abortion was associated with a birth rate decrease twice that for the pill.
Among white minors, having had access to the pill was associated with a 9% drop in the overall birthrate and an 8% drop in the rate of nonmarital first births. In this same group, access to an abortion was correlated with a 17% decline in the nonmarital birthrate and a 16% decline in the rate of nonmarital first births.
Another study found that, for women under age 19, "liberalized abortion policy predicts a 34 percent decline in motherhood" whereas "the results do not provide evidence that pill policies had a substantial effect." The author explains
The birth control pill’s effects on family formation are theoretically ambiguous: The pill was a technological innovation in contraception, but with a failure rate of about 9 percent in the first year of typical use (Trussell, 2004), it still provides an imperfect means of preventing pregnancy. Trends in sexual behavior suggest that any reductions in unintended pregnancies among teens due to safer, pill-protected sex were offset by large increases in sexual activity. Difference-in-difference estimates also provide little evidence to support the view that pill policies had a substantial influence on age at first birth and marriage. Results in Goldin and Katz (2002) and Bailey (2006, 2009) that suggest otherwise are not robust to reasonable perturbations of the authors’ research designs including addressing discrepancies in the legal codings, choosing alternative data sets, and/or adjusting sample selection procedures. Rather, the results robustly point to policies governing abortion, a second, less lauded but more certain means of preventing unwanted births, as the driving force behind delayed family formation in the 1970s. [Emphasiss added]
This study is not a perfect comparison to claims about more modern contraception. The idea is that the most effective forms of contraception (e.g. IUDs instead of the Pill) do a better job of decreasing unintended pregnancy rates because even if users increase their sexual activity as a result, the increase in risk-taking behavior does not offset the decrease in risk these more effective contraceptive methods provide.

Note also that research suggests when abortion is legalized the abortion rate increases more than the birth rate decreases. See Footnote 8 of this report, p8 of the PDF, which explains in part:
Note, however, that the decline in births is far less than the number of abortions, suggesting that the number of conceptions increased substantially --and example of insurance leading to moral hazard. The insurance that abortion provides against unwanted pregnancy induces more sexual conduct or diminished protections against pregnancy in a way that substantially increases the number of pregnancies. [Emphasis added]
People are less cautious about avoiding pregnancy when they know they can get abortions as a back up option. This idea is further substantiated by a study published in the June 2015 edition Perspectives on Sexual and Reproductive Health which concluded:
Women who lived in a state where abortion access was low were more likely than women living in a state with greater access to use highly effective contraceptives rather than no method (relative risk ratio, 1.4). Similarly, women in states characterized by high abortion hostility (i.e., states with four or more types of restrictive policies in place) were more likely to use highly effective methods than were women in states with less hostility (1.3).
This research also suggests that teasing out the effects of abortion access compared to contraception use may prove challenging, since the two appear to be inversely correlated.

So with that brief overview of just a few studies, so far these are the conclusions I'm drawing:
  1. Abortion restrictions decrease abortion rates (and likely also unintended pregnancy rates).
  2. Access to the most effective forms of contraception decrease abortion rates.
  3. Abortion restrictions probably decrease abortion rates more than access to less effective contraception (e.g. the Pill) does, and
  4. It's unclear whether abortion restrictions or access to the most effective forms of contraception (e.g. IUDs) decrease abortion rates more.
I'm open to other suggestions or studies if you have them.

[This article is reposted with permission from Difficult Run.]