Birth control, or contraception, is the use of any method, medicine, or device to prevent pregnancy. While there is no perfect method of birth control other than abstinence, there are several methods available today which include non-hormonal (read here) and hormonal (read here) options. Plan B (known as “morning-after pills”) and oral contraceptives (known as “the pill”), are both short-acting hormonal methods of contraception, therefore, both under the same drug classification. What are the differences between the two?
Plan B is for emergencies: when the primary method of birth control fails, or after unprotected intercourse. It is single-use and readily available for purchase over-the-counter, whereas the pill is usually accessible through a prescription from a physician and recommended for continuous use - following a 21 or 28 day cycle.
There are two types of Plan Bs available: levonorgestrel (LNG) and Ulipristal acetate (UPA). They differ in hormones, dosage, function, and effectiveness after a certain period of time. Since UPA is a recent innovation, and only approved by the European Medicines Agency and the US Food and Drug Administration, LNG is commonly used.
LNG is a synthetic progestogen that is used in a single dose of 1.5mg taken within 72 hours of unprotected intercourse or a two-dose regimen of 0.75mg within the first 72 hours and a second 0.75mg tablet 12 hours afterwards [1]. When taken before ovulation, the luteinizing hormone (LH) will become suppressed, preventing the release of the egg, ovulation, and fertilization. However, taking it after ovulation also prevents pregnancy by thickening the cervix (interfering with sperm migration) and thinning the uterine mucus (making implantation more difficult) [2-4].
For birth control pills, there are progestin-only and a combination of both progestin and estrogen. In terms of dosage, none exceeds 0.125mg, which is one twelfth of a Plan B dosage. Furthermore, the combination pill works similarly when taken before ovulation, while progestin-only works alike when taken after ovulation [5,6].
In sum, even though Plan B and birth control pills are similar in their goal and function, they differ in hormones, dosage, and usage - they are not interchangeable! After discussing in length about women’s contraceptives, stay tuned for our next text on new research for men’s!
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Written by: Phaedra
Edited by: Natasha
BioDecoded is aware that Birth Control has generated much controversy and litigation, but we believe accurate information about the mechanisms of action and safety can allow our readers, especially women, to make more informed decisions. We cannot offer any specific health advice. If you have any doubts about your personal health, please speak with your healthcare professional or family physician. Your doctor can revise your medical history and advise you on the best path to follow. If you have any questions about this topic or would like to learn more, please comment below or send us your questions.
References:
Mikolajczyk, R. and Stanford, J. (2007) "Levonorgestrel emergency contraception: a joint analysis of effectiveness and mechanism of action", Fertility and Sterility, 88(3), pp. 565-571. Available at: https://www.fertstert.org/article/S0015-0282(06)04732-7/fulltext
Gemzell-Danielsson, K. (2010) "Mechanism of action of emergency contraception", Contraception, 82(5), pp. 404-409. Available at: https://www.contraceptionjournal.org/article/S0010-7824(10)00321-5/fulltext
NDavidoff, F. and Trussell, J. (2006) "Plan B and the Politics of Doubt", JAMA, 296(14), p. 1775. Available at: https://jamanetwork.com/journals/jama/article-abstract/203551
Shohel, M. et al. (2014) "A systematic review of effectiveness and safety of different regimens of levonorgestrel oral tablets for emergency contraception", BMC Women's Health, 14(1). Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3977662/
Your Hormones and Hormonal Birth Control: What You Should Know (2023). ADYN. Available at: https://adyn.com/blog/your-hormones-and-hormonal-birth-control-what-you-should-know/ (Accessed: 9 April 2023).
Schrager S. et al (2023). "Beyond Birth Control: Noncontraceptive Benefits of Hormonal Methods and Their Key Role in the General Medical Care of Women”. Journal of Women's Health, 29(7). Available at: https://www.liebertpub.com/doi/10.1089/jwh.2019.7731?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed
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