Does emergency contraception affect fertility?

Emergency contraception, better known by its brand name, Plan B, can be taken after unprotected sex to prevent pregnancy. It can be purchased over the counter at your local pharmacy. However, on social media, there is some sense of worry that emergency contraception will affect future fertility, especially if taken repeatedly. Let’s think twice: does emergency contraception affect fertility?

Emergency contraception typically consists of the hormone levonorgestrel, which is a synthetic form of the hormone progesterone (1). Progesterone is a natural hormone in the body that helps regulate the menstrual cycle and increases during pregnancy (2). Levonorgestrel delays ovulation to prevent pregnancy (3).

A 2022 systematic review of levonorgestrel emergency contraception analyzed 33 studies and found that it did not affect fallopian tube mobility, ectopic pregnancy, miscarriage, stillbirth, or subsequent menstruations (3). Another systematic review of 47 studies found that adverse outcomes like ectopic pregnancy and miscarriage were not significantly associated with taking levonorgestrel emergency contraception (4). Researchers reported that “the most common adverse effects of levonorgestrel were not serious.” Temporary side effects reported after emergency contraception use include nausea and vomiting, vaginal bleeding, and fatigue (7). In one observational study of 232 participants reported transient changes in their menstruation (6).

A 2014 systematic review of 22 studies evaluated the repeated use of emergency contraception as the primary source of contraception and reported that the most common side effect was menstrual irregularities (5). The researchers concluded that more investigation is required since the existing studies on repeated usage were not methodologically sound. Also, many menstrual cycles are irregular and pregnancy alone might alter them, making objective measurement of the cycle for several months before and after important, which is difficult and perhaps impossible.

Emergency contraception can reduce the probability of conception after unprotected sex (8) and is a safe and effective medication that does not impact future fertility.

Sources

Gillson, George. “Clarifying hormone terminology.” Canadian family physician Medecin de famille canadien vol. 53,1 (2007): 29-30.

Cable JK, Grider MH. Physiology, Progesterone. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK558960/

Endler, M et al. “Effect of levonorgestrel emergency contraception on implantation and fertility: A review.” Contraception vol. 109 (2022): 8-18. doi:10.1016/j.contraception.2022.01.006

Leelakanok, Nattawut, and Janthima Methaneethorn. “A Systematic Review and Meta-analysis of the Adverse Effects of Levonorgestrel Emergency Oral Contraceptive.” Clinical drug investigation vol. 40,5 (2020): 395-420. doi:10.1007/s40261-020-00901-x

Halpern, Vera et al. “Repeated use of pre- and postcoital hormonal contraception for prevention of pregnancy.” The Cochrane database of systematic reviews vol. 2014,9 CD007595. 26 Sep. 2014, doi:10.1002/14651858.CD007595.pub3

Gainer, Erin et al. “Menstrual bleeding patterns following levonorgestrel emergency contraception.” Contraception vol. 74,2 (2006): 118-24. doi:10.1016/j.contraception.2006.02.009

World Health Organization. “Emergency Contraception.” (2021). https://www.who.int/news-room/fact-sheets/detail/emergency-contraception#:~:text=Emergency%20contraception%20(EC)%20can%20prevent,assault%20if%20without%20contraception%20coverage.

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