Definition and Epidemiology

In the United States, 99% of sexually active women have used contraception at some time in their lives. From 2006 to 2010, 62% of women aged 15 to 44 years reported that they were currently using contraception. The most common types of contraception are oral contraception, female sterilization, and condoms. Unfortunately, 47% of the women who have used more than one method of contraception have chosen to change or stop owing to dissatisfaction.¹

From 2006 to 2010, 37% of all births were unintended.² Given the high frequency of unplanned pregnancy, it is essential that health care providers educate and counsel women and their partners on the variety of feasible contraception options. It is imperative that the woman (and her partner, if desired) be involved in the care plan rather than be merely a recipient of the provider’s expertise and advice. Discussion of contraceptive options should include information about the risks and benefits, potential side effects, rate of efficacy, and effects on future fertility.

When possible emotional and health care costs are factored in, all methods of contraception have been shown to be more cost-effective than unintended pregnancy.³ Current methods of contraception are continuously improved and new contraceptives are constantly being developed, resulting in an ever-evolving variety of patient-centered, cost-effective choices.

Estrogen is one of the two major hormonal components in combined oral contraceptives. The role of estrogen in combined oral contraceptives is to promote bleeding regularity and to suppress the release of follicle-stimulating hormone.^4,5 The basic chemical structure of estrogen has been modified by pharmaceutical manufacturers to increase effectiveness, leading to the development of the two synthetic estrogens (ethinyl estradiol and less commonly mestranol) that are used in combined oral contraceptives today. The doses of ethinyl estradiol used in the first oral contraceptives were often in excess of 100 µg, resulting in side effects that decreased the safety profile of the medication. Subsequent research and experience have proved that doses of 50 µg or less are sufficient to aid in the suppression of ovulation while minimizing side effects.

These estrogen compounds are delivered with a synthetic progestin, the second active hormonal compound. The progestin component provides the majority of the contraceptive effect by suppressing follicle-stimulating hormone and luteinizing hormone. This altered hormonal environment prevents ovulation, thickens cervical mucus, and promotes a uterine atmosphere that is hostile to implantation.^4,5 Several different formulations of synthetic progestins are commonly used in combined oral contraceptives in the United States. Newer third- and fourth-generation progestins are less adrenergic, limiting such side effects as acne, hirsutism, and hyperlipidemia.⁴

Several different types of OCPs are available and vary according to the dose of hormones and the formulations within each cycle pack. Monophasic OCPs have a constant dose of estrogen and progestin in each of the active tablets of the cycle pack. Phasic OCPs have alternating doses of progestin and, in some cases, estrogen throughout the cycle. The aim of manufacturers in lowering the total monthly exogenous hormone dose while trying to simulate a woman’s normal menstrual cycle is to reduce the metabolic side effects associated with OCP use.

The first oral contraceptive regimens provided 21 days of active hormone followed by 7 days of inert pills, resulting in a withdrawal bleed. The 21/7 regimen was initially adopted because the creators of the OCP believed that women would appreciate the reassurance of a monthly period. Alternating regimens offer additional benefits of decreasing unpleasant symptoms and inconvenience associated with withdrawal bleeding. The FDA has approved the use of several extended OCP regimens consisting of 84 days of active pills and 7 days of nonhormonal pills. Other preparations provide a regimen of 24 active days followed by 4 days of inert pills, resulting in decreased side effects caused by estrogen withdrawal, lighter menses, and decreased likelihood of ovulation.^6,7

With perfect use, OCPs are 99.7% effective in preventing pregnancy. However, with typical use in the United States, the rate of efficacy drops to 91%.⁸ At the time of prescription, the absence of pregnancy should be verified via standard laboratory tests. Traditionally, women have been instructed to begin the regimen of OCPs on either the first day of menses or on the first Sunday after menses begin, a method known as the conventional start. This approach ensures that the patient is not pregnant and in the case of a Sunday start aligns the days on the packaging with the actual day of the week. Another approach, known as the quick start, has the patient begin the regimen on the day of the visit, as the hormones in the contraceptive do not harm the fetus if the woman is pregnant at that time. Studies have shown that both methods have similar rates of effectiveness and side effects, leaving opportunity for provider and patient choice.⁹

Women should be encouraged to take OCPs at the same time every day and to associate pill taking with a certain daily habit or ritual if that facilitates compliance. Daily compliance is essential to ensuring efficacy. Women who miss one or two tablets should take two tablets for each of the missed days. Women who miss more than 2 days should continue taking the pills as prescribed but use an additional form of birth control for the remainder of the cycle. Women who often miss doses of OCPs should be encouraged to consider a form of fertility control that does not depend on daily compliance.

Secondary analysis of National Survey for Family Growth data suggests that 29% of women discontinued oral contraceptives because of dissatisfaction. Of those women, 64.6% discontinued because of side effects, and 13.1% of women discontinued OCPs because they were worried about side effects.² The extent and type of side effects differ slightly among individual OCPs because of variations in the amount and kind of estrogen and progestin contained within each product.

Nausea, breast tenderness, and mild fluid retention resulting from the estrogen component of OCPs are common side effects. Menstrual changes, including intermenstrual (breakthrough) spotting or bleeding, occur in 25% of women during the first 3 months of OCP use and decrease significantly during subsequent prolonged use. Other estrogen-related side effects include increased breast size (ductal and fatty tissue), cervical hyperplasia, benign hepatocellular adenomas, increased skin pigmentation, and cholelithiasis.¹⁰

Women with persistent intermenstrual bleeding after 3 months of OCP use should be evaluated for possible causes of bleeding unrelated to OCP use. Amenorrhea may also occur, especially in women who have been using OCPs for a prolonged period. Other possible side effects include a decreased libido (decreased interest in sex or the decreased ability to have an orgasm), fluid retention, leukorrhea, pruritus, and headaches.

Some of the “short-lived” side effects associated with OCPs tend to dissipate by the third or fourth cycle. Once the responsible hormonal component has been identified, the provider can determine whether the side effect is caused by an excess or deficiency and can present potential alternative contraceptive options that may lead to increased satisfaction.

Benefits of oral contraceptives extend beyond that of preventing pregnancy. There is a reduced risk of formation of ovarian cysts. Lighter menses may result in a decrease in the incidence or severity of iron deficiency anemia. Some women may notice a decrease in premenstrual mood symptoms and premenstrual cramping. OCPs are known to decrease the incidence of fibrocysts in the breasts. Most combined oral contraceptives—in particular some triphasic preparations—are known to help control acne. Other advantages may include increased bone density and decreases in the incidence of pelvic inflammatory disease (PID), endometrial and ovarian cancers, and rheumatoid arthritis.¹¹

OCPs also have significant health risks and disadvantages, including a lack of protection against human immunodeficiency virus (HIV) infection, a greater threat to the health of many sexually active individuals than an unplanned pregnancy. To protect against HIV infection and other sexually transmitted infections, barrier methods (e.g., condoms) must be used in conjunction with OCPs.

The estrogen component in OCPs has been shown to cause mild increases in both systolic and diastolic blood pressure, which may be more pronounced in some patients. Blood pressure returns to baseline after the cessation of OCPs. There is a lack of data demonstrating a link between OCPs and myocardial infarction, although women who have hypertension and smoke may be at risk. Current practice recommendations are that women with a blood pressure lower than 140/90 mm Hg are good candidates for OCPs. Women with well-controlled hypertension who are younger than 35 years and do not smoke, have no comorbidities, and have no end-organ damage are also considered good candidates for combined oral contraceptives. All women should have their blood pressure monitored at each clinic visit.^5,12,13

Potential for thromboembolism is another infrequent but serious adverse effect associated with combined oral contraceptives. Although the risk is quite low, thromboembolism occurs three times more frequently in women who take OCPs than in those who do not. The effect appears to be more pronounced in women who are obese; in women with a history of thromboembolism; and in women who have venous stasis, coagulopathies, and vascular injury.^12–14

There is a questionable relationship between OCPs and stroke. The risk is most likely increased in women who have coagulopathies, women who smoke, and those older than 35 years of age. There may also be an increased risk of ischemic stroke with OCP use in women with a history of migraines with aura. Although the risk is low, morbidity associated with stroke is devastating enough that current recommendations suggest that migraine sufferers use a progestin-only contraceptive or nonhormonal form of contraception.^12–14

The potential impact of OCP use on breast cancer is a concern for a great number of women interested in this form of fertility control. There continues to be debate as to the degree of effect of OCPs on the development of breast cancer. Many of the studies showing an association between OCP use and breast cancer are older and apply to preparations that included a much higher dose of estrogen than is used today. Women should be counseled that there may be a slightly increased risk of breast cancer with OCP use. Studies have not proved an increased risk in OCP users with a first-degree relative who has a history of breast cancer; therefore, current practice guidelines do not treat family history as a contraindication.^12,15,16

The World Health Organization’s medical eligibility criteria for contraceptive use, published in September 2010, provide comprehensive guidance for the safety of use of different contraceptive methods. OCPs should not be prescribed for the following women: those who are breastfeeding and are less than 6 weeks postpartum; smoke more than 15 cigarettes per day; have a systolic blood pressure of 160 mm Hg or higher or a diastolic blood pressure of 100 mm Hg or higher; have a current or past history of deep vein thrombosis or pulmonary embolus; are immobilized for extended periods of time after surgery; have a history of coronary artery disease or stroke; have a genetic disease that predisposes them to clotting; or have systemic lupus erythematosus, diabetes and end-organ damage, or severe liver diseases. Caution should be used in prescribing OCPs to the following women: those who have blood pressure higher than 140/90 mm Hg; have adequately controlled hypertension; are less than 3 weeks postpartum; are breastfeeding and are 6 weeks to 6 months postpartum; smoke fewer than 15 cigarettes per day; have diabetes mellitus; have hyperlipidemia; have migraines without aura and are older than 35 years; or are taking anticonvulsants.¹⁴

The warning signs to teach OCP users can be summarized with the acronym ACHES:

Newer Progestins.

The spironolactone derivative drospi­renone has been combined with ethinyl estradiol (30 µg) to form several newer monophasic oral contraceptives. Drospi­renone is a fourth-generation progestin that is a spironolac­tone analogue with antimineralocorticoid and antiandrogenic properties. A dose of 3 mg/day displays antimineralocorticoid activity similar to that of 25 mg of spironolactone, which may be a good choice in women who experience significant sodium and water retention during their cycle. Drospirenone also is thought to be less likely to exacerbate acne and to mitigate premenstrual symptoms. Hyperkalemia is a potential adverse effect related to the potassium-sparing effects of drospirenone.¹⁸

Dienogest is a relatively new and very potent antiandrogenic progestin that also allows for good cycle control. Dienogest is available in both biphasic and quadriphasic preparations. Although similar to drospirenone, dienogest does not require the monitoring of potassium levels, because it lacks antimineralcorticoid activity.¹⁸

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