The most effective reversible birth control methods are the IUD and implant, with a failure rate of less than 1%. But these obviously couldn't live right there on aisle six since they need to be inserted by a doctor. Ditto for the contraceptive shot (which has a failure rate of between 1–6%), which involves an injection by your doctor every three months.
So, when we talk about prescription-free birth control, we're really talking about the pill, the patch, and the ring. While still very effective methods, they're susceptible to more user error. With typical use, these methods can have up to a 9% failure rate.
So it's possible that OTC birth control could affect which methods some women use. "The whole point of the Affordable Care Act contraceptive coverage piece is that if you take the cost barrier away, then women can choose from the full range of methods and find whats perfect for them," Rachel Fey, director of public policy at the National Campaign, told BuzzFeed Health.