Conventional, monophasic, combined oral contraceptives are traditionally administered daily for 21 days, followed by a seven-day hormone-free interval. Oral contraceptives contain estrogen and progestogen in different doses and formulations. By extending the days on the active pill, bleeding can be delayed and fewer periods per year can occur. In addition to being convenient and thus improving the quality of life of women in need of contraception, long-cycle oral contraceptive regimens have been used to treat gynecological conditions, particularly those causing cyclical pelvic pain such as dysmenorrhoeic conditions and endometriosis. Oral contraceptives used in a long cycle, i.e. by extending the intervals between pill-free periods to more than 21 days, or completely without a hormone-free interval, offer important benefits. The number of bleeding days and menstrual problems are reduced. The pain associated with endometriosis and the risk of disease recurrence after surgical treatment are reduced by oral contraceptives taken continuously. The risk of endometrial hyperplasia has not been shown to increase. Traditionally, oral contraceptives are designed to deliver a low dose of female sex hormones, either estrogen and progesterone in combination, or progesterone alone, for 21 days, with a fourth week without any hormones. This allows time for the endometrium to shed, called withdrawal bleeding. In the typical 28-day pill cycle, the active hormones are taken for 21 days, during which time progesterone action is observed on the endometrium. During the next 7 days, the placebo allows unimpeded estrogenic action. Since there is no inhibition of follicle-stimulating hormone, estradiol is produced by the ovaries. This leads to the growth of the endometrium, which is quickly suppressed by the active pills. The purpose of prolonged or prolonged use is thus to eliminate endometrial growth, thereby preventing withdrawal bleeding. Breakthrough bleeding is due to endometrial atrophy rather than endometrial shedding because there is no thickened decidualized endometrium to shed. Delaying periods for a long time can lead to a higher incidence of breakthrough bleeding or spotting—bleeding between periods—which can be uncomfortable. This happens more often during the first few months of continuous use. As the physiology adapts to the continuous low-dose regimen, these phenomena usually diminish over time. Breakthrough bleeding is more likely if a woman fails to take a pill on time or also uses drugs that speed up the metabolism of the hormones in birth control pills. The herbal supplement St. John’s wort also has the same effect. In case of vomiting or diarrhea, the pill is absorbed less efficiently,which can cause breakthrough bleeding due to lower hormonal effects on the endometrium. In the case of uncontrollable breakthrough bleeding, it may be better to switch to the typical 21-day cycle with one week of inactive pills before the next course of active hormone pills. Sometimes it may be possible to stop for three days after at least 21 consecutive days on the active pills to allow bleeding to occur. This should be followed by a tablet of active ingredients for 21 or more days, starting on the fourth day after stopping. Long-term use of contraceptives can hide an existing pregnancy, in case of contraceptive failure. For this reason, women taking long-term oral contraceptives should monitor for symptoms of unexplained nausea and vomiting, new breast tenderness, or unusual fatigue. References: https://www.mayoclinic.org/healthy-lifestyle/birth-control/in-depth/womens-health/art-20044044. Tobah, YB (2020). How Long Can I Safely Take Birth Control Pills? https://www.mayoclinic.org/healthy-lifestyle/birth-control/expert-answers/birth-control-pills/faq-20058110. Burnett, T. (2020). Is Breakthrough Bleeding More Common with Extended-Cycle Birth Control Pills, Such as Seasonale and Others? https://www.mayoclinic.org/healthy-lifestyle/birth-control/expert-answers/seasonale-side-effects/faq-20058109.