Usage
When a woman takes COCP, the hormones in the pills prevent both ovulation and shedding of the endometrium (menstruation). Traditionally, COCPs are packaged with 21 active (hormone-containing) pills and 7 placebo pills. During the week of placebo pills, withdrawal bleeding occurs and simulates an average 28-day menstrual cycle. The placebo pills are not required for pregnancy protection, and with any monophasic COCP the placebo pills may be discarded, and the next pack of active pills may be started to prevent the withdrawal bleeding. With bi- and tri-phasic pills, skipping the placebo week results in a sudden change in hormone levels, which may cause irregular spotting or flow. (Monophasic pills offer the same dose of estrogen and progestogen whereas multiphasic pills have varying doses from day to day; see formulations for details.) Recently, several pharmaceutical companies have gained FDA approval to package COCPs for the intended use of reducing the frequency of or eliminating withdrawal bleeding. Clinical indications
Extended or continuous use of COCPs has been used for many years to treat endometriosis, dysmenorrhea, and menstruation-associated symptoms. Some studies have suggested that women who experience premenstrual-type symptoms during the placebo (hormone-free) week of traditionally packaged COCPs may experience significantly fewer symptoms when placed on extended cycle COCP regimens.More recently, personal preference to avoid menstruation has also become a common reason for use. Personal preference is the most common reason extended cycle or continuous use COCPs are prescribed to adolescents.
Extended or continuous cycle combined oral contraceptive pills are a packaging of combined oral contraceptive pills (COCPs) that reduce or eliminate the withdrawal bleeding that would occur once every 28 days in traditionally packaged COCPs. It works by reducing the frequency of the pill-free or placebo days. Extended cycle use of COCPs may also be called menstrual suppression,  although other hormonal medications or medication delivery systems (hormonal intrauterine devices—IUDs) may also be used to suppress menses. Any brand of combined oral contraceptive pills can be used in an extended or continuous manner by simply discarding the placebo pills; this is most commonly done with monophasic pills in which all of the pills in a package contain the same fixed dosing of a synthetic estrogen and a progestin in each active pill.Other combined hormonal contraceptives (those containing both an estrogen and a progestin) may also be used in an extended or continuous cycle. For example, the NuvaRing vaginal ring and the contraceptive patch have been studied for extended cycle use, and the monthly combined injectable contraceptive may similarly eliminate bleeding. History
Before the advent of modern contraceptives, reproductive age women spent most of their time either pregnant or nursing. In modern Western society, women typically have about 450 periods during their lives, as compared to about 160 formerly.Although it was evident that the pill could be used to suppress menstruation for arbitrary lengths of time, the original regimen was designed to produce withdrawal bleeding every four weeks to mimic the menstrual cycle.