Randomized Controlled Trial (RCT) of...

Subsidized Contraception for Low-Income U.S. Women to Prevent Unintended Pregnancies

Reviewed

Unplanned Pregnancy Prevention
Not accurately reported

NBER (October 2025) posted findings from the M-CARES study – a large, high-quality RCT evaluating the impact of providing low-income women with vouchers making the full spectrum of available contraception highly discounted or free. Despite the study abstract’s claimed findings of fewer pregnancies and abortions, the study found no impact on pregnancies or abortions over two years in its preregistered primary analysis. 

We use a randomized controlled trial to examine how the costs of contraception affect method choice, pregnancy, abortion, and childbirth among U.S. women. The study recruited women seeking care through Title X—a national family planning program subsidizing reproductive health services for low-income Americans—and randomized vouchers making the full spectrum of available contraception highly discounted or free.  We find that subsidizing contraception has large and persistent effects on the choice of contraceptive method, resulting in significantly fewer pregnancies and abortions within two years. Subsidizing contraception negatively affected births, but the effect was not significant at two years.

Full Study Report

We use a randomized controlled trial to examine how the costs of contraception affect method choice, pregnancy, abortion, and childbirth among U.S. women. The study recruited women seeking care through Title X—a national family planning program subsidizing reproductive health services for low-income Americans—and randomized vouchers making the full spectrum of available contraception highly discounted or free. We find that subsidizing contraception has large and persistent effects on the choice of contraceptive method.  However, our primary analysis finds no effects on key fertility outcomes—including pregnancies, abortions, and births—within two years. In supplementary analyses accounting for heterogeneity of effects across subgroups and phases of the trial, we find suggestive evidence of reductions in pregnancies and abortions that may warrant examination in future research.  resulting in significantly fewer pregnancies and abortions within two years. Subsidizing contraception negatively affected births, but the effect was not significant at two years.

No-Spin’s Study Overview

Large, high-quality RCT of subsidized contraception for low-income women finds large effects on women’s choice of contraceptive method – including increased use of Long-Acting Reversible Contraception (LARCs) – but no effects on the number of pregnancies, abortions, or births over two years in the study's preregistered primary analysis.

Program and Study Design:

  • The Michigan Contraceptive Access, Research, and Evaluation Study (M-CARES) randomly assigned 4,192 women seeking care through Title X – a national family planning program for low-income Americans – to (i) a treatment group that received vouchers making the full spectrum of available contraception highly discounted or free; or (ii) a control group that did not receive vouchers.
  • The women were 18-35 years old and were not pregnant or wishing to become pregnant in the next 12 months. Most had incomes between 100% and 250% of the federal poverty line. 51% of the women assigned to the treatment group used their vouchers.
  • Based on our careful review, this was a high-quality RCT (e.g., large sample, baseline balance, low sample attrition).

Findings:

  • The study found large, statistically significant effects on contraception choice during the first 100 days (when vouchers were valid) – including, for example:
    • An increase in the purchase of any contraception from 37% (control group) to 53% (treatment group); and
    • An increase in LARC insertion from 5% (control group) to 14% (treatment group).
  • However, the study found no impact on fertility outcomes over the two years after study entry, including women’s average number of pregnancies (0.27 treatment vs. 0.27 control); abortions (0.20 treatment vs. 0.21 control); and births (0.042 treatment vs. 0.035 control).

Comment:

  • This is one of numerous examples in the history of RCTs in which a program affects intermediate outcomes (in this case, contraceptive methods) but not the ultimate targeted outcomes (in this case, unplanned pregnancies).
  • The study's inaccurate claim of a 12% reduction in abortions was cited in a New York Times opinion column.
  • Disclosure: Arnold Ventures, which funds No-Spin Evidence Review, helped fund the M-CARES study.

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