Plan B emergency contraception serves as a backup method to prevent pregnancy after unprotected sexual intercourse or contraceptive failure. It is designed to quickly reduce the chance of an unintended pregnancy. This medication is not intended for routine use as a primary birth control method. Plan B is a single-dose oral tablet for use within a specific timeframe following an unprotected sexual encounter.
Scientific Foundations of Emergency Contraception
The concept of post-coital contraception has roots in early scientific understanding of reproductive hormones. In 1966, Drs. John M. Morris and Gertrude van Wagenen at Yale School of Medicine published research demonstrating that certain estrogenic compounds could prevent pregnancy if administered within a few days after intercourse. Their studies, conducted with rhesus macaque monkeys, explored the idea of “interceptives” that would prevent implantation of a fertilized egg. Their research inspired further investigation into hormonal emergency contraception.
Building on this foundational knowledge, researchers continued to explore hormonal methods. In 1977, Drs. A. Albert Yuzpe and Lance developed an emergency contraception regimen for humans. This approach, known as the Yuzpe method, involved using a combination of ethinylestradiol and levonorgestrel at higher doses. This combination regimen was widely used as an emergency contraceptive until newer, more focused treatments became available.
Developing the Plan B Product
The specific product known as Plan B was developed by Barr Laboratories, which was later acquired by Teva Pharmaceutical Industries. Barr Laboratories pursued the development of a levonorgestrel-based emergency contraceptive pill to offer a more effective option with fewer side effects than the existing Yuzpe method. The company’s efforts culminated in the first progestin-only morning-after pill, Plan B, which received approval from the U.S. Food and Drug Administration (FDA) in July 1999.
Initially, Plan B was available by prescription only and consisted of two tablets, with the first taken within 72 hours of unprotected sex and the second 12 hours later. Barr Laboratories later sought over-the-counter (OTC) status for Plan B, submitting an application to the FDA in April 2003. This application initiated a regulatory and public debate regarding access to emergency contraception. The FDA eventually approved Plan B One-Step, a single 1.5 mg levonorgestrel dose, for unrestricted OTC sale in 2013.
How Plan B Works
Plan B primarily works by preventing or delaying ovulation, the release of an egg from the ovary. The synthetic hormone levonorgestrel, present in Plan B, achieves this by disrupting the midcycle hormonal changes necessary for egg release. By delaying ovulation, the medication ensures no egg is available for fertilization by sperm, thus preventing pregnancy.
Plan B does not work if a person is already pregnant. It does not affect an existing pregnancy and is not an abortion pill. Scientific evidence supports that Plan B has no direct effect on the implantation of a fertilized egg in the uterine lining or on post-fertilization processes. The medication is most effective when taken as soon as possible after unprotected sex, ideally within 72 hours, although it can be used up to five days later with decreasing effectiveness.
Societal Impact and Availability
The introduction of Plan B and its subsequent journey to wider availability impacted reproductive health and family planning discussions. When Barr Laboratories first sought over-the-counter status in 2003, it sparked public debate, with women’s health advocates arguing for improved access to reduce unintended pregnancies and conservative groups raising concerns about its use.
Despite recommendations from FDA expert panels to approve OTC status, the agency initially declined in 2004, citing concerns about use by younger teenagers. This decision led to further legal challenges and political pressure. After years of regulatory changes and legal actions, Plan B One-Step was eventually approved for unrestricted over-the-counter sale in 2013, meaning it could be purchased without age restrictions or identification requirements. Challenges related to misinformation and varying pharmacy practices still affect its availability.