Continuous Pill Use; A Review

From a review discussing the impact of menstrual disorders, symptoms and associated conditions on women and the evidence in support of the safe induction of amenorrhea with continuous OC use:

Menstruation has an important impact on quality of life for many women, ranging from a simple inconvenience to a major health concern for those suffering from menstrual disorders and conditions that are aggravated during menstruation. Up to 80% of reproductive-aged women experience physical changes associated with menstruation, and 20% to 40% experience menstrual-cycle-related symptoms. Recognized menstrual-cycle-related disorders affect approximately 2.5 million women between the ages of 18 and 50 years in the United States alone.

...

Menstruation and menstrual disorders have a broader economic impact on women and society, which is a direct result of time lost from work and decreased productivity. Texas Instruments noted a 25% reduction in the productivity of female workers during menses as one example. The total economic cost of menstrual disorders in the United States is estimated to be 8% of total wages, with dysmenorrhea alone estimated at US$2 billion annually and menorrhagia estimated at US$1692.00 annually per woman.

...

While not life-threatening, primary dysmenorrhea [painful period] is the most common reason for absenteeism from work and/or school among women younger than 30 years.

...

There appears to be a relationship between epilepsy and the menstrual cycle. It has been apparent for over 100 years that menstruation can increase the occurrence of epileptic seizures, referred to as catamenial epilepsy....A large retrospective study of 265 women with epilepsy and 142 control subjects recently confirmed previous smaller reports that women with epilepsy have an increased frequency of menstrual disorders.

...

Menstruation has a single biological purpose: to allow the endometrium to be reprogrammed for implantation of a fertilized ovum.

...

Hormonal contraceptives were originally developed, employing a regimen of 21 days of active drug followed by 7 drug-free days, in an effort to mitigate the perception that they would interfere with the normal menstrual cycle and to make the concept of hormonal contraception more acceptable to women, clinicians and the Roman Catholic Church. There were practical reasons for the 21-day/7-day regimen as well. While women today have easy access to accurate and affordable pregnancy tests, the majority of women relied on the occurrence of regular menstrual bleeding to determine if they were not pregnant before the pill was originally designed and marketed. The traditional OC regimen is an artifact of that bygone era, rather than a scientifically established truth. Clinicians realized from the beginning that OCs could prevent bleeding as long as they are taken, producing a cycle or interval of any desired length.

...

Women 100 years ago began menstruating at the age of 16 years, had their first child at 19.5 years of age and gave birth six times between the ages of 20 and 34 years. As a consequence, they only experienced an average of 160 menstrual cycles during their lives. Modern women begin menstruating much earlier, at an average age of 12.5 years, and have fewer children (two children on average in the United States), which translates into more than 450 menstrual cycles over their lifetime.

...

Since the early days of OC use, studies about reducing the number of pill-free periods have shown that it is a safe and effective option for many women.

...

A recent review evaluated the differences between cyclic (21-day) and continuous use (>28 days) of OCs. Due to the significant differences between published studies, the authors were unable to perform a meta-analysis; however, the authors concluded that the available evidence suggests that continuous use of OCs offers comparable contraceptive efficacy and safety to cyclic OC regimens. Bleeding patterns were either similar or improved with continuous OC use. Where evaluated, the incidence of cycle-related symptoms (such as headaches, tiredness and menstrual pain) was reduced with continuous OC regimens.

...

When women are allowed to choose their cycle length and duration of pill-free interval, they clearly prefer extended cycles and shorter pill-free periods. Among women who were permitted to set their own hormone-free intervals (n=220), most (60%) continued using extended cycles for more than 2 years, with 88% choosing a hormone-free interval of ≤4 days, with no serious sequelae or pregnancy.

...

Furthermore, women using continuous OC regimens miss fewer pills, particularly during the first day and first week of the cycle. Current low-dose OCs contain the minimum hormone doses required to prevent ovulation; if the pill-free period is extended by even 1 day, follicular development may occur and the risk of ovulation increases. Similarly, missed or delayed pills affect cycle control, and a single missed pill can result in breakthrough bleeding. A retrospective analysis of data from large multicenter trials found that inconsistent OC use is associated with a 60% to 70% increase in the risk of intermenstrual bleeding. Continuous use of OCs may improve compliance and thereby increase both contraceptive effectiveness and patient satisfaction.

...

Many women derive health and quality-of-life benefits by eliminating their menstrual cycle, which may reduce the occurrence of menstrual-cycle-related disorders such as menorrhagia, dysmenorrhea and anemia.

...

OC use [on a regular, 21/7 regimen] is associated with a reduced incidence of ovarian and endometrial cancers, benign breast disease, pelvic inflammatory disease, ectopic pregnancy and anemia. Links to OC use to increase bone mineral density and decreases in uterine leiomyomas, toxic shock syndrome and colorectal cancer are currently being investigated.

...

Although they are different phenomena, the symptomatology of menstruation is similar to what many women experience during the hormone withdrawal period (Fig. 2). Nausea, breast tenderness, headaches, bloating and cramping occurred significantly more often (p<.001) during the pill-free week than while taking active drug when evaluated over several 28-day cycles in 262 OC users. These symptoms are frequent reasons for discontinuing OCs and may be alleviated by eliminating the pill-free interval. With continuous OC use, the total number of bleeding days is dramatically decreased, as well as other symptoms including headache, cramps and bloating. ... There are many groups of women who may particularly benefit from reduced or eliminated menstrual cycles. Many women in the military (>60%) report that menstrual or premenstrual symptoms have affected their ability to perform physical tasks and have created problems with regard to changing, obtaining and disposing of hygiene products. Female athletes commonly take OCs to protect bone health, to eliminate or postpone bleeding and to control menstrual symptoms. Virtually all perimenopausal women experience cycle irregularity, and OCs regulate menses and suppress other perimenopausal symptoms such as hot flashes, which worsen during the pill-free period. In the United States, tubal sterilization is the most common form of contraception; this large group of sterile women continue to menstruate with no possibility of pregnancy. For all of these women, amenorrhea through continuous OC use could improve their quality of life.

Last, but not least:

The physiological purpose of menstruation is to prepare the uterus for pregnancy; however, monthly hormone withdrawal bleeding in women taking OCs to prevent pregnancy cannot be considered to have a physiological or biological purpose, and it is not a physiological requirement. Current cyclic OC regimens were not designed based on empirical scientific evidence but out of a desire to suit the needs and allay the fears of both women and society. Effective contraception is no longer the radical concept that it once was, and women clearly want more options for both contraception and cycle control. The availability of a continuous use of orally active estrogen and progestin combination used to eliminate or reduce menstruation would offer improved quality of life and provide greater lifestyle convenience for many women. Use of this regimen could be dissociated from the need for contraception and is indicated for alleviating menstrual-cycle-related symptoms.