Does Expanding Access to Affordable Birth Control Reduce Unintended Pregnancies?
Bailey et al. (2026) examine whether making contraception more affordable reduces unintended pregnancies among uninsured American women. They conducted a randomized controlled trial involving 4,192 women receiving reproductive health services at 13 Michigan clinics, using medical records and follow-up surveys to track outcomes over 26 months. They found that contraceptive subsidies increased purchases of long-acting contraceptives by 11 percentage points (213%) and encouraged women to choose more effective methods. Subsidies reduced pregnancies by 17% (3.5 percentage points) and abortions by 12% (2.1 percentage points). Approximately 86% of prevented pregnancies would have been unintended. Effects on childbirth were statistically inconclusive.
Why This Article Was Selected for The Policy Scientist
Access to affordable contraception has important implications for reproductive health, family formation, economic security, and public expenditures. Understanding whether financial barriers influence pregnancy outcomes is particularly timely amid continuing debates over federal funding for family planning services and reproductive health policy. Martha Bailey has contributed extensively to research on contraception and its economic consequences. This study makes an important contribution by establishing whether reducing contraceptive costs changes behavior and pregnancy outcomes. Its randomized controlled trial provides unusually strong evidence of causality, supported by detailed medical records and longitudinal surveys.
Full Citation and Link to Article
Bailey, M. J., Brito, E., Gorgulu, D., Figone, K., Lang, V. W., Prettyman, A., & Dalton, V. K. (2026). "Does increasing financial access to contraception in the U.S. reduce unintended pregnancies? Evidence from the M-CARES randomized controlled trial at two years". American Economic Review: Insights. Advance online publication (forthcoming).
Central Research Question
Does making contraception more affordable reduce unintended pregnancies among uninsured women in the United States? This study examines whether out-of-pocket costs prevent women from obtaining their preferred contraceptive methods and whether eliminating these financial barriers reduces pregnancies, abortions, and childbirth. The central question concerns the causal relationship between contraceptive affordability and reproductive outcomes, rather than simply whether women who use more effective contraception experience fewer pregnancies.
The researchers investigate whether temporarily subsidizing the full range of contraceptive methods produces lasting changes in contraceptive choices and pregnancy outcomes. Their analysis focuses on uninsured women seeking reproductive health services through clinics participating in the federal Title X family planning program. Although Title X subsidizes contraception for lower-income Americans, substantial out-of-pocket expenses can remain, particularly for highly effective methods such as intrauterine devices (IUDs) and contraceptive implants. The study evaluates whether eliminating these costs changes contraceptive purchases, increases the use of more effective methods, and reduces unintended pregnancies over a 26-month period.
Previous Literature
Research examining the relationship between contraceptive access and reproductive outcomes extends across several decades. Early contributions by Blake (1969), Ryder and Westoff (1971), and Becker (1981) examined how family planning, contraceptive availability, and individual preferences influence fertility. Subsequent research investigated whether government interventions could meaningfully change reproductive behavior or whether fertility primarily reflected underlying preferences concerning childbearing.
More recent studies have examined specific contraceptive policies in the United States. Kearney and Levine (2009) found that Medicaid family planning expansions reduced birth rates, particularly among teenagers. Lindo and Packham (2017) and Kelly et al. (2020) examined Colorado's Family Planning Initiative, which expanded access to long-acting reversible contraceptives and contributed to reductions in teenage births. However, other interventions produced less consistent results. Buckles and Hungerman (2018) found that distributing condoms in high schools sometimes increased teenage births when distribution was not accompanied by counseling. Research on Delaware's contraceptive access initiative also identified increased contraceptive use without correspondingly large reductions in pregnancy outcomes.
Experimental evidence remains comparatively limited. Dupas et al. (2025), using a randomized controlled trial in Burkina Faso, found that providing free contraception had negligible effects on contraceptive use and fertility. These contrasting findings highlight the importance of population characteristics, existing healthcare systems, and intervention design. The present study extends this literature by using random assignment to isolate the effects of contraceptive subsidies among American women actively seeking reproductive healthcare.
Data
The researchers use data from the Michigan Contraceptive Access, Research, and Evaluation Study (M-CARES), a randomized controlled trial conducted between August 2018 and February 2023. Participants were recruited from 13 Planned Parenthood health centers in Michigan. The study enrolled 4,192 women between ages 18 and 35 who were physically capable of becoming pregnant, were not currently pregnant, did not intend to become pregnant within the following year, and faced out-of-pocket contraceptive expenses.
Of these participants, 2,063 were randomly assigned to receive contraceptive vouchers, while 2,129 were assigned to the control group. The vouchers made contraceptive methods free or substantially discounted for 100 days. Approximately 76% of randomized participants completed the two-year follow-up survey, producing a final analytical sample of 3,172 women.
The researchers combined three sources of information: follow-up surveys, Planned Parenthood administrative and medical records, and Michigan birth records. These data documented contraceptive purchases, method effectiveness, pregnancies, abortions, miscarriages, and childbirth over 26 months. Administrative records were particularly important because survey respondents frequently failed to report abortions. Approximately 46% of abortions documented in clinic records were absent from participants' survey responses. Combining administrative and survey information therefore improved the measurement of pregnancy outcomes and reduced reliance on potentially incomplete self-reported information.
Methods
The study employs a randomized controlled trial to identify the causal effects of contraceptive subsidies. Participants were randomly assigned to receive a voucher or remain in the control group, creating comparable populations that differed primarily in their financial access to contraception. Random assignment reduces the possibility that observed differences in pregnancy outcomes reflect preexisting characteristics such as income, education, contraceptive preferences, or previous childbearing.
The researchers estimate two types of treatment effects. First, intention-to-treat estimates measure the consequences of being offered a contraceptive voucher, regardless of whether participants used it. Second, instrumental variables estimates measure the effects of actually using the voucher, with random assignment serving as the instrument. The instrumental variables analysis employs generalized method of moments estimation and accounts for differences in voucher use across clinics, participant characteristics, and intervention phases. The researchers also examine alternative specifications to assess the robustness of their findings.
This distinction matters because approximately 51% of participants offered vouchers used them. The researchers therefore distinguish between the effects of offering financial assistance and the effects among women whose contraceptive purchases were influenced by that assistance. Their approach provides stronger evidence of causality than conventional observational comparisons, although interpreting voucher-use estimates requires additional statistical assumptions.
Findings/Size Effects
The researchers find that reducing contraceptive costs substantially changes women's contraceptive choices. During the first 100 days, voucher use increased the probability of purchasing contraception by 27 percentage points, representing a 72% increase relative to the control group. Total contraceptive spending increased by $336, or 290%, indicating that subsidies encouraged purchases that otherwise might not have occurred.
Voucher use also increased the effectiveness of contraceptive methods purchased. The failure rate of the most effective method selected declined by 25 percentage points, representing a 74% reduction. Purchases of long-acting reversible contraceptives, including IUDs and implants, increased by 11 percentage points, or 213%. Additionally, women purchased contraceptive methods providing an average of 255 additional days of coverage, a 168% increase. These differences persisted for at least 26 months, despite the vouchers being available for only 100 days.
The generosity of the subsidy substantially influenced contraceptive decisions. When vouchers covered approximately half the cost of expensive contraceptive methods, their effects on long-acting contraceptive use were relatively small and statistically insignificant. When subsidies increased to cover the full cost, the estimated increase in long-acting contraceptive use became substantially larger. This finding suggests that partial subsidies may leave significant financial barriers in place.
Most importantly, increased contraceptive access translated into fewer pregnancies. After 26 months, voucher use reduced pregnancies by 3.5 percentage points, equivalent to a 17% reduction relative to the control group. Abortions declined by 2.1 percentage points, representing a 12% reduction. Based on participants' reported pregnancy intentions, the researchers estimate that approximately 86% of prevented pregnancies and nearly all prevented abortions would have involved unintended pregnancies.
Although childbirth also declined among voucher users, the estimated effect was statistically inconclusive. The confidence interval included both increases and decreases in births, preventing a definitive conclusion about this outcome. Consequently, the strongest evidence concerns changes in contraceptive choices, pregnancies, and abortions rather than childbirth.
Conclusion
The study provides experimental evidence that contraceptive costs influence reproductive decisions and pregnancy outcomes among uninsured American women seeking family planning services. Making contraception substantially less expensive increases the use of effective contraceptive methods and reduces pregnancies and abortions over a period exceeding two years.
The findings demonstrate that financial barriers can persist even when contraceptive services are already subsidized through existing public programs. They also establish that changes in contraceptive purchases can translate into measurable changes in pregnancy outcomes, rather than merely shifting spending from patients to subsidy providers.
The randomized design, combined with longitudinal surveys and administrative medical records, strengthens the causal interpretation of these findings. Nevertheless, the results apply most directly to uninsured women actively seeking reproductive healthcare in Michigan. Their applicability to insured populations, women not seeking contraceptive services, or jurisdictions with different healthcare systems remains uncertain.
The broader contribution is evidence that the price of contraception affects both the methods women select and their subsequent reproductive outcomes. The results provide a basis for evaluating how contraceptive subsidy policies may influence unintended pregnancies, while distinguishing their demonstrated effects on pregnancies and abortions from the less certain consequences for childbirth.
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