Modeling the Potential Benefit of an Over-the-Counter Progestin-Only Pill in Preventing Unintended Pregnancies in the U.S.
Authors: Guillard Hélène , Laurora Irene , Sober Stephanie , Karapet Artin , Brass Eric P. , Glasier Anna 
Published: May 2023

Almost half of the 6.1 million annual pregnancies are unintended. Barriers to accessing contraception including prescription requirements contribute to inconsistent use or nonuse. This has led to a call from major medical organizations for effective over-the-counter (OTC) contraceptives such as progestin-only pills (POPs). Studies have modeled the potential impact on an OTC POPs; however, they are based on women expressing interest versus actual use.

The objective of this model was to utilize data from an actual-use clinical trial to calculate the potential impact of a POP, when they are available over the counter, on the number of unintended pregnancies in the United States. Data were obtained from a recent actual-use clinical trial that simulated OTC use of a norgestrel POP over a 6-month period. In this study, 883 women chose to pay out of pocket and use the norgestrel POP. This model compared the number of expected pregnancies among 2 cohorts of 100,000 women, one of which was based on the contraceptive mix of volunteers entering the actual-use trial, and the second was women exclusively using an OTC POP. The primary analysis set the failure rate of the OTC POP to 7%, the reported failure rate for oral contraceptive pills, and that of “no method” as 85%. The failure rate of the non-OTC POP cohort was that from the actual-use trial. A “tipping point” analysis was conducted to determine the failure rate of the OTC POP beyond which no unintended pregnancies would be prevented by OTC POP compared with the mixed-method cohort. At the 6-month time point in the actual-use trial, only 51.1% of subjects were continuing OTC POP use. A continuation-in-use analysis was conducted to determine what effect discontinuation might have on unintended pregnancy rate.

According to the model, a total of 37,624 unintended pregnancies would occur if 100,000 women continued their current contraceptive method over the course of 1 year. If those 100,000 women had used the OTC POP exclusively for 1 year, 7000 unintended pregnancies would be expected. Thus, an estimated 30,624 fewer unintended pregnancies, a reduction of 80%, would be expected over 1 year by use of an OTC POP. The results of a sensitivity analysis that decreased the OTC POP failure rate from 7% to 3.5% resulted in an estimated 34,124 fewer unintended pregnancies and an increase in OTC POP failure rate to 10.5%, and reduction of “no method” failure rate to 46% resulted in an estimated 1461 fewer unintended pregnancies. The tipping point analysis identified an OTC POP typical use failure rate of 38% at the point which using the OTC actual-use trial method mix profile and a “no method” failure rate of 85% would result in equivalent unintended pregnancy rate to the OTC POP cohort. When revising estimates according to the continuation-in-use analysis, a reduction in unintended pregnancies of 59% over 6 months compared with the actual-use trial method mix profile (11,009 pregnancies prevented) was calculated.

The results of this study suggest that the use of a POP when available over the counter will result in a significant reduction of unintended pregnancies in the United States.