Progestin-only pills came into medical use in 1968 in France.[1] There are currently a number of progestin-only formulations.[3] One, norgestrel, was approved for over the counter sale in 2023, in the United States.[7][3] No testing is required before starting.[4] In the United States they cost between 25 USD and 200 USD per month as of 2023.[3]
The theoretical efficacy is similar to that of the combined birth control pill (CBCP). However, this pill is taken continuously without any breaks between packets, and traditional progestogen-only pills must be taken to a much stricter time every day (within 3 hours vs. a CBCP's 12 hours). However, in some countries, the POP desogestrel has an approved window of 12 hours. The effectiveness is, therefore, dependent upon compliance.
Lacking the estrogen of combined pills, they are not associated with increased risks of deep vein thrombosis or heart disease. With the decreased clotting risk, they are not contraindicated in the setting of sickle-cell disease. The progestin-only pill is recommended over regular birth control pills for women who are breastfeeding because the mini-pill does not affect milk production (estrogen reduces the amount of breast milk). Like combined pills, the minipill decreases the likelihood of pelvic inflammatory disease.[8]
It is unclear whether POPs provide protection against ovarian cancer to the extent that CBCPs do.
There are fewer serious complications than with CBCPs.[9]
With no break in the dosage, menstrual flow does not initially occur at a predictable time. Most women tend to establish, over a few months, light to heavy spotting at irregular intervals.
May cause mastalgia (breast tenderness, pain) and mood swings, as well as panic attacks, anxiety and depression.
Some women may experience abdominal cramps and heavy bleeding.
Epidemiological evidence on POPs and breast cancer risk is based on much smaller populations of users and so is less conclusive than that for COCPs.
In the largest (1996) reanalysis of previous studies of hormonal contraceptives and breast cancer risk, less than 1% were POP users. Current or recent POP users had a slightly increased relative risk (RR 1.17) of breast cancer diagnosis that just missed being statistically significant. The relative risk was similar to that found for current or recent COCP users (RR 1.16), and, as with COCPs, the increased relative risk decreased over time after stopping, vanished after 10 years, and was consistent with being due to earlier diagnosis or promoting the growth of a preexisting cancer.[17][18]
The most recent (1999) IARC evaluation of progestogen-only hormonal contraceptives reviewed the 1996 reanalysis as well as 4 case-control studies of POP users included in the reanalysis. They concluded that: "Overall, there was no evidence of an increased risk of breast cancer".[19]
Recent anxieties about the contribution of progestogens to the increased risk of breast cancer associated with HRT in postmenopausal women such as found in the WHI trials[20] have not spread to progestogen-only contraceptive use in premenopausal women.[21]
Association of use with depression is unclear as of 2021, with some studies finding lower risks and other studies higher risks.[22] A Danish study of one million women reported that the use of hormonal contraception, particularly amongst adolescents, was associated with a increased risk of subsequent depression.[23] The authors found that women on the progestogen-only pill in particular, were 34% more likely to subsequently take anti-depressants or be given a diagnosis of depression, in comparison with those not on hormonal contraception.[23] A similarly large nationwide cohort study in Sweden amongst women aged 12–30 (n=815,662) found an association, particularly amongst young adolescents (aged 12–19), between hormonal contraception and subsequent use of psychotropic drugs.[24]
The mechanism of action of progestogen-only contraceptives depends on the progestogen activity and dose.[21]
Very-low-dose progestogen-only contraceptives, such as traditional progestogen-only pills (and subdermal implants Norplant and Jadelle and intrauterine systems Progestasert and Mirena), inconsistently inhibit ovulation in ~50% of cycles and rely mainly on their progestogenic effect of thickening the cervical mucus, thereby reducing sperm viability and penetration.
Intermediate-dose progestogen-only contraceptives, such as the progestogen-only pill Cerazette (or the subdermal implant Nexplanon), allow some follicular development (part of the steps of ovulation) but much more consistently inhibit ovulation in 97–99% of cycles.[26] The same cervical mucus changes occur as with very-low-dose progestogens.
High-dose progestogen-only contraceptives, such as the injectables Depo-Provera and Noristerat, completely inhibit follicular development and ovulation. The same cervical mucus changes occur as with very-low-dose and intermediate-dose progestogens.
In anovulatory cycles using progestogen-only contraceptives, the endometrium is thin and atrophic. If the endometrium were also thin and atrophic during an ovulatory cycle, this could, in theory, interfere with implantation of a blastocyst (embryo).
↑ 1.01.11.21.3Annetine Gelijns (1991). Innovation in Clinical Practice: The Dynamics of Medical Technology Development. National Academies. pp. 172–. NAP:13513. Archived from the original on 2023-07-15. Retrieved 2023-07-11. Syntex was the first to introduce a 0.5 milligram chlormadinone acetate minipill in 1968 in France, although this pill was withdrawn from the market in 1970 when long-term animal toxicity tests for the FDA revealed the occurrence of breast nodules in beagles. Nevertheless, other manufacturers began to pursue minipill development using their own progestogens, and since 1970 a variety of compounds have been introduced.
↑ 15.015.115.2Population Reports: Oral contraceptives. Department of Medical and Public Affairs, George Washington Univ. Medical Center. 1975. p. A-64. Archived from the original on 2023-07-15. Retrieved 2023-07-11. Distribution and Use of the Minipill. [...] Progestogen & Dose in mg: d-Norgestrel 0.03. Manufacturer: Schering AG. Brand Names: Microlut, Nordrogest. Where & When First Marketed: Federal Republic of Germany 1971.
↑Collaborative Group on Hormonal Factors in Breast Cancer (1996). "Breast cancer and hormonal contraceptives: further results". Contraception. 54 (3 Suppl): 1S–106S. doi:10.1016/s0010-7824(15)30002-0. PMID8899264.
↑IARC Working Group on the Evaluation of Carcinogenic Risks to Humans (1999). "Hormonal contraceptives, progestogens only". Hormonal contraception and post-menopausal hormonal therapy; IARC monographs on the evaluation of carcinogenic risks to humans, Volume 72. Lyon: IARC Press. pp. 339–397. ISBN92-832-1272-X. Archived from the original on 2006-09-28. Retrieved 2023-07-11.
↑ 21.021.1Glasier, Anna (March 20, 2015). "Chapter 134. Contraception". In Jameson, J. Larry; De Groot, Leslie J.; de Krester, David; Giudice, Linda C.; Grossman, Ashley; Melmed, Shlomo; Potts, John T., Jr.; Weir, Gordon C. (eds.). Endocrinology: Adult and Pediatric (7th ed.). Philadelphia: Saunders Elsevier. p. 2306. ISBN978-0-323-18907-1.
↑McCloskey, Leanne R.; Wisner, Katherine L.; Cattan, Minaz Kolia; Betcher, Hannah K.; Stika, Catherine S.; Kiley, Jessica W. (1 March 2021). "Contraception for Women With Psychiatric Disorders". American Journal of Psychiatry. 178 (3): 247–255. doi:10.1176/appi.ajp.2020.20020154.
↑Lopez, LM; Ramesh, S; Chen, M; Edelman, A; Otterness, C; Trussell, J; Helmerhorst, FM (28 August 2016). "Progestin-only contraceptives: effects on weight". The Cochrane Database of Systematic Reviews. 2016 (8): CD008815. doi:10.1002/14651858.CD008815.pub4. PMC5034734. PMID27567593. We found little evidence of weight gain when using POCs. Mean weight gain at 6 or 12 months was less than 2 kg (4.4 lb) for most studies. The groups using other birth control methods had about the same weight gain.
↑Pattman, Richard; Sankar, K. Nathan; Elewad, Babiker; Handy, Pauline; Price, David Ashley, eds. (November 19, 2010). "Chapter 33. Contraception including contraception in HIV infection and infection reduction". Oxford Handbook of Genitourinary Medicine, HIV, and Sexual Health (2nd ed.). Oxford: Oxford University Press. p. 360. ISBN978-0-19-957166-6. Ovulation may be suppressed in 15–40% of cycles by POPs containg levonorgestrel, norethisterone, or etynodiol diacetate, but in 97–99% by those containing desogestrel.360&rft.edition=2nd&rft.pub=Oxford+University+Press&rft.date=2010-11-19&rft.isbn=978-0-19-957166-6&rft_id=https://books.google.com/books?id=sTWXAwAAQBAJ&pg=PA353&rfr_id=info:sid/mdwiki.org:Progestogen-only+pill" class="Z3988">
↑ 27.027.1Bennett, John P. (1974). "The Second Generation of Hormonal Contraceptives". Chemical Contraception. pp. 39–62. doi:10.1007/978-1-349-02287-8_4. ISBN978-1-349-02289-2. Chlormadinone acetate was the first minipill contraceptive to be marketed, in Mexico during July 1968. This compound was removed from clinical use in February 1970 because it produced nodules in the breast tissues of beagle dogs [...]
↑ 31.031.1J. Larry Jameson; Leslie J. De Groot (18 May 2010). Endocrinology - E-Book: Adult and Pediatric. Elsevier Health Sciences. pp. 2424–. ISBN978-1-4557-1126-0. Archived from the original on 15 July 2023. Retrieved 11 July 2023. In 2002, a POP containing desogestrel 75 ug/day, a dose sufficient to inhibit ovulation in almost every cycle, was introduced in Europe.51