Contraception
Lisa Memmel
Melissa Gilliam
Reproductive rights embrace certain human rights that are already recognized in national laws, international human rights documents, and other relevant consensus documents. These rights rest on the recognition of the basic right of all couples and individuals to decide freely and responsibly the number and spacing and timing of their children and to have the information and means to do so, and the right to attain the highest standard of sexual and reproductive health.
—Beijing Platform for Action, 1995
All women have a basic human right to determine whether and when they will become pregnant. Sexually active women and men have a wide variety of contraceptive choices for implementing this right, ranging from temporary to permanent methods. Most women have the potential to become pregnant over at least 3 decades of their lives, and most men are fertile for virtually their entire adulthood. Thus, a series of different contraceptive decisions may be made over a person’s reproductive life span. Since 2000, the range of contraceptive choices in the United States has increased with a wide range of new contraceptive methods, including a vaginal ring, a contraceptive patch, a progestin-releasing intrauterine device (IUD), an implantable contraceptive device, and a transcervical method of tubal occlusion. This chapter focuses on information with which the health professional can counsel women and men to make the contraceptive choices that best address their needs and circumstances.
Contraceptive Use in the United States and around the World
Data from the U.S. National Survey of Family Growth indicate that in 2002, 61.9% of women between the ages of 15 and 44 used some method of contraception. Among women who used contraception, permanent methods were the most popular; 16.7% had undergone tubal sterilization, and 6.3% had partners who had undergone vasectomy. Oral contraceptives were the most popular temporary method, but the proportion of pill users decreased from 27% of contraceptive users in 1995 to 19% in 2002. In addition, the proportion of condom users decreased from 20.0% in 1995 to 11.1% in 2002. Only 3.3% and 1.0%, respectively, used the injectable depot medroxyprogesterone acetate (DMPA) and the IUD. Despite this level of reported contraceptive use, 49% of pregnancies concluding in 2002 were unintended, with 42% of those ending in elective abortion.
Globally, according to the Demographic and Health Surveys, tubal sterilization is the most common method of contraception (in 1997, 20% of couples in which the woman was of reproductive age and who used a contraceptive method used tubal sterilization), followed by IUDs (15%), oral contraceptives (8%), and condoms (5%).
Choosing a Method of Contraception
Although sterilization is the most widely used method of contraception in the United States and in much of the rest of the world, it is appropriate only for women and couples who have made a decision to permanently prevent pregnancy. Thus, many couples will choose reversible contraceptive methods. Factors that influence the appropriateness of any contraceptive choice include the relative safety and effectiveness of the method for that individual, the frequency and acceptability of side effects, the willingness and ability to use the method consistently and correctly, cost, and the importance of personal factors such as societal attitudes as well as religious or cultural beliefs regarding method acceptability. Other factors include the frequency of coitus, the length of time that intended pregnancy is to be delayed, the impact on lactation and the breast-fed infant, and any potential impact of the method on future
fecundity. In addition, many women are at risk for sexually transmitted infections, including HIV infection, and must consider dual goals of protection against pregnancy and prevention of sexually transmitted infections. Doing both entails the correct and consistent use of condoms or use of another contraceptive method in conjunction with condoms. The need for such dual protection produces special challenges, as there is some evidence that the use of a highly effective method of contraception other than condoms may affect a person’s willingness or ability to use condoms for disease prevention.
fecundity. In addition, many women are at risk for sexually transmitted infections, including HIV infection, and must consider dual goals of protection against pregnancy and prevention of sexually transmitted infections. Doing both entails the correct and consistent use of condoms or use of another contraceptive method in conjunction with condoms. The need for such dual protection produces special challenges, as there is some evidence that the use of a highly effective method of contraception other than condoms may affect a person’s willingness or ability to use condoms for disease prevention.
Contraceptive Effectiveness
Contraceptive effectiveness is measured as reduction in the probability of conception with use of a contraceptive method over a defined period; it cannot be measured directly, largely because studies cannot determine the proportion of women in a given population who would have become pregnant during that time had they not been using contraception. By contrast, contraceptive failure rates can be directly determined and are the most clinically useful measures of effectiveness. Yet, it is important to note the limitations of the widely used Pearl Index method in which contraceptive failures occur per 100 woman-years of use, which limits the comparability of the new method being studied to an older regimen. Instead, the life-table method, which considers failures over time, may be preferable.
Widely used estimates of contraceptive failure rates are shown in Table 32.1. These rates are provided in two categories: “typical use” and “perfect use.” The former is similar to “use effectiveness” and is characteristic of a typical couple starting to use a method (some use the method properly and others do not); the latter is similar to “method effectiveness,” which is the result of consistent and correct use of the method. For some methods, the typical and perfect use rates are substantially different, which indicates that the user’s willingness and ability to use these methods consistently and correctly are more important than they are for those methods that have similar typical and perfect use rates. For example, according to Trussell and colleagues (Table 32.1), although women who take a combined oral contraceptive (COC) pill each day should have a near-zero probability of pregnancy, 8% of couples in which the woman initiates use of oral contraceptives experience an unintended pregnancy during the first year if they do not discontinue pill use for any other reason. By contrast, the typical and perfect use failure rates are virtually the same for IUD users and for users of etonorgestrel implants. Published estimates of contraceptive failure rates apply to groups and may vary substantially among individuals within those groups, particularly among those who use methods with major differences in estimates between typical and perfect use. Most failure rates address the risk of pregnancy within 12 months of starting to use the method. The risk of pregnancy for some methods, particularly those that depend on proper use, is likely to decline over time.
Oral Contraception
Combined Oral Contraceptives
COCs, which contain both estrogen and a progestin, have been available in the United States since 1960, have been used by millions of women worldwide, and have been extensively studied. Formulations for oral contraceptives have changed over time from higher to lower doses of the synthetic components. Today, COCs prescribed in the United States contain between 20 and 35 mcg of ethinyl estradiol. The progestin component of COCs varies and may include a first-generation progestin (estranes) such as norethindrone, norethindrone acetate, ethynodiol diacetate, and norethynodrel; a second-generation progesti, (gonanes), including levonorgestrel and norgestrel; or a third-generation progestin such as desogestrel, norgestimate, and gestodene (gestodene is not available in the United States). A recently developed contraceptive uses drospirenone, a spironolactone derivative, as its progestin. Monophasic pills have constant doses of estrogen and progestin, whereas multiphasic pills vary the doses of estrogen, progestin, or both throughout the cycle.
The primary mechanism of progestins is inhibition of ovulation by suppressing follicle-stimulating hormone and luteinizing hormone. In addition, the pharmaceutical progestin thickens the cervical mucus, impeding the ascent of sperm into the upper genital tract, lowers embryo receptivity of the endometrium, and may also act by altering tubal transport. Although COCs are highly effective in preventing pregnancy when used consistently and correctly, 29% of COC users reported missing one or more pills or not starting on time in the last 3 months in the 1995 National Survey of Family Growth. COCs are substantially less effective when used inconsistently (i.e., as seen with many typical users) (Table 32.1).
Metabolic Effects
The estrogen and progestin components of COCs induce some metabolic changes, but for most healthy women, the changes associated with the current low-dose COCs have little or no clinical significance.
Estrogens generally alter lipid metabolism in a fashion that is considered beneficial, including slightly increasing levels of high-density lipoprotein (HDL) and decreasing low-density lipoprotein (LDL). Depending on their level of androgenicity, progestins can counteract these effects, decreasing HDL and increasing LDL. Therefore, the net effect depends on the doses of both estrogen and progestin as well as the type of progestin; however, most changes are within the normal range and not clinically relevant.
TABLE 32.1 Percentage of Women Experiencing an Unintended Pregnancy during the First Year of Typical Use and the First Year of Perfect Use of Contraception and the Percentage Continuing Use at the End of the First Year in the United States | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Although some studies of older formulations of high-dose COCs reported progestin-associated elevated glucose and insulin levels and higher rates of relative peripheral insulin resistance, clinical studies of low-dose COCs have not found clinically significant effects on glucose metabolism. A large, cross-sectional study of U.S. women found no elevation in hemoglobin A1C, fasting glucose, insulin, and C-peptide levels among current COC users compared with those who never used COCs. Large, prospective studies have not found increased risks of diabetes mellitus among COC users with either high-dose or low-dose pills.
Cardiovascular Diseases
Epidemiologic research confirms that the overall risk of serious cardiovascular complications attributable to COC use is extremely low for the vast majority of users of the current low-dose ethinyl estradiol preparations (≤35 mcg). However, individual user characteristics and the type of COC modify the risk. Cardiovascular complications associated with COC use occur while the pill is being used; once pills are discontinued, risk levels return to baseline.
Hypertension
COC use may slightly increase blood pressure among normotensive women, but studies suggest that this increase is reversible when COC use is discontinued. Among women with mild hypertension, COC use also has been associated with increased blood pressure. In a cross-sectional study of 94 women with mild hypertension, COC users had significantly increased daytime and nighttime ambulatory systolic blood pressure values (mean 8.3 mm Hg increase for daytime and mean 6.1 mm Hg increase for nighttime). No significant differences in diastolic blood pressure values were found.
Venous Thromboembolism
The incidence rate of venous thromboembolism (VTE) in healthy nonpregnant white women is estimated to be between 10 and 30 per 100,000 woman-years. When such women use COCs, the incidence increases to between 30 and 120 per 100,000 woman-years, or three to four times higher than non-COC users, depending on personal characteristics and the type of pill. By comparison, the risk of thrombosis associated with pregnancy is about 200 per 100,000 pregnant women. The case fatality rate of VTE is 1 to 2 per 100 and the risk of death from thromboembolism attributable to COC use is extremely low, at 1 to 5 per million per year of use. The most important risk factor for thromboembolism is family history of the disease, which often is related to genetic thrombophilia. The most common genetic cause of thrombophilia is resistance to activated protein C (factor V Leiden mutation), which occurs in about 5% of whites but is rare in non-whites. The presence of the factor V Leiden mutation substantially increases the risk of COC-associated venous thrombosis; screening for the condition before starting pill use has been considered. However, cost–benefit considerations lead most authorities to recommend against screening before starting COCs unless women have a family history of thrombosis.
The third-generation low-dose pills with the progestins desogestrel or gestodene have been associated with a nearly two-fold increased risk of thrombosis relative to second- generation or first-generation pills, which contain levonorgestrel or norethindrone. Although these elevated risks are noteworthy, they are nonetheless very low in absolute terms—an estimated excess of 4 deaths per 1 million woman-years of use.
Stroke and Myocardial Infarction
Older age, smoking, diabetes, and hypertension are major risk factors for arterial diseases such as stroke and myocardial infarction. For women with these risk factors, COC use increases their already elevated baseline risk; thus, women with multiple major risk factors for cardiovascular disease generally should not use COCs.
The annual incidence rates of hemorrhagic and ischemic stroke in healthy, nonsmoking women between 20 and 24 years of age are estimated to be 2.0 and 0.5 per 100,000, respectively. In women between 40 and 44 years of age, these annual rates are 5 and 1 per 100,000, respectively. Non-smoking women younger than 35 years with normal blood pressure who use COCs have no extra risk of hemorrhagic stroke and only a marginally increased risk of ischemic stroke. Among such women 35 years or older, the risk of hemorrhagic or ischemic stroke is increased 1.5- to 2-fold during use of COCs. Smoking and hypertension increase the COC-associated risk of hemorrhagic and ischemic stroke. Use of COCs by women with classic migraine further elevates their moderately increased risk of ischemic stroke.
In healthy, non-smoking women of reproductive age with normal blood pressure, the risk of myocardial infarction is extremely low, and the use of COCs causes little if any increase in risk. On the other hand, women who smoke, have hypertension, or have hyperlipidemia elevate their baseline risk of myocardial substantially by COC use. Myocardial infarction is rare in women younger than 35 years, even if they have risk factors; for women 30 to 34 years old who use COCs and smoke, the risk is estimated to be 2 per 100,000 woman-years. By contrast, women 40 to 44 years old who use COCs and smoke have an estimated risk of 25 per 100,000 woman-years. Some studies suggest that women who take pills containing the progestins desogestrel or gestodene may have an even lower risk of myocardial infarction than that associated with the very low risk of pills containing levonorgestrel or norethindrone, but findings are inconsistent.
Malignant Neoplasia
COCs clearly reduce the risk of some cancers and may increase the risk of some others. Most data are based on COCs with higher doses of estrogens and progestins than in
the currently available pills; studies suggest that lower-dose preparations are likely to have similar effects on cancer risk.
the currently available pills; studies suggest that lower-dose preparations are likely to have similar effects on cancer risk.
Breast Cancer
A pooled analysis of 54 studies found a small increased risk of breast cancer (relative risk = 1.24) while COCs were being used or recently discontinued. The excess risk was among women with localized disease, and there was a corresponding decrease in metastatic disease. These findings argue that women who use COCs are:
Simply more likely to have existing breast cancers diagnosed because they are more likely to have clinical exams or mammograms
More likely to have late-stage promotion of tumors that subsequently are more likely to remain localized to the breast.
The observation that the duration of COC use does not increase breast cancer risk argues for the former explanation. The excess risk of breast cancer disappears 10 years after cessation of pill use. Thus, women who use the pill from age 15 to age 35 years have the same breast cancer risk at age 50 as comparable women who never took COCs. Because the incidence of breast cancer is low at ages when COC use is most common, any effect would affect a relatively small number of women. For example, among women who stop using COCs at 25 years of age, the cumulative risk from ages 25 through 34 years is estimated to be 1 excess cancer diagnosed per 10,000 women. In women who stop COC use at age 40, when incidence rates are higher, an estimated 19 excess cancers will be diagnosed from ages 40 through 49 years. As noted, even these excess cancers may represent only an earlier detection of existing disease; at worst, they represent a small absolute excess occurrence of localized disease.
Cervical Cancer
In the past, several studies suggested that COC use of 5 years or longer increased the risk of cervical cancer 1.3- to 1.8-fold, but the causality of this association was uncertain. Persistence of genital human papillomavirus (HPV), particularly HPV 16 and 18, cause cervical cancer, and oral contraceptive users may be more likely to have sexual intercourse and less likely to use a barrier method of contraception. Exposure to COCs does cause eversion of the columnar epithelial cells of the cervix exposing these metaplastic cells to sexually transmitted HPV virus. A meta-analysis has shown that the relative risk of cervical cancer with COC use is 1.1 after 5 years and 2.2 for women who have used COCs for 10 or more years. Available data suggest that the increased risk decreases over time after stopping pill use. Questions remain about whether the risk is related to pill use per se; to other characteristics of pill users, such as sexual behavior; or to other factors associated with pill use, such as cytologic screening. Regardless, where screening services are available, COC users should avail themselves of these services as advised for other women. COC users do not require special screening procedures or recommendations.
Ovarian Cancer
Use of COCs reduces the risk of epithelial ovarian cancer, the most common type of cancer of the ovary. Risk reduction is positively correlated with the duration of use. Using COCs for 5 years or longer confers at least a 50% reduced risk that persists for up to 15 years after cessation of use.
Endometrial Cancer
COC use reduces the risk of cancer of the endometrium. As with ovarian cancer, the risk reduction is related to duration of use. After 5 years of use, the risk of endometrial cancer is at least 50% lower than in women who never used COCs. Furthermore, the risk reduction persists for 15 to 20 years after stopping pill use.
Liver Tumors
Long-term use of high-dose oral contraceptives has been associated with the development of benign liver tumors such as focal nodular hyperplasia and adenomas. Though benign, adenomas of the liver can lead to significant problems related to rupture of the liver capsule. In COC users who have an enlarged liver or tenderness to palpation on physical examination, the COC should be stopped and evaluation is warranted.
Primary cancer of the liver is rare in populations where hepatitis B or C is not endemic. Some studies in the 1980s pointed to a substantially increased risk of primary liver cancer after long-term use of COCs. In populations where chronic hepatitis is common, pill use has not been associated with primary liver cancer. Liver cancer is rare and usually fatal within 1 year of diagnosis; thus, the fact that there has been no increase in liver cancer deaths in the United States in the 4 decades that COCs have been in widespread use argues against any substantial risk.
Other Cancers
Some studies have found a lower incidence of colon cancer among women who have used COCs, but it is unclear whether the association is causal. Previous speculation of an increased risk of tumors of the pituitary and the skin in users of COCs have not been confirmed.
Medical Eligibility Criteria for Combined Oral Contraceptive Use
Most women can safely use COCs. There are, however, some conditions under which COCs should not be used. These conditions include the following:
Age >35 years and smoking >15 cigarettes per day
Multiple risk factors for arterial cardiovascular disease (e.g., older age, smoking, diabetes, hypertension)
Elevated blood pressure of 160 mm Hg systolic or 100 mm Hg diastolic hypertension with vascular disease
Current or history of deep vein thrombosis or pulmonary embolism
Major surgery with prolonged immobilization
Current or history of ischemic heart disease
Stroke
Complicated valvular heart disease
Migraine with focal neurologic symptoms (migraine with aura)
Migraine without focal neurologic symptoms and age >35 years
Current breast cancer
Diabetes with nephropathy, retinopathy, neuropathy, vascular disease, or diabetes of >20 years duration
Severe cirrhosis
Liver tumors.
In addition, there are several other conditions in which women generally should not use COCs (Table 32.2).
Noncontraceptive Benefits of Combined Oral Contraceptive Use
In addition to protecting against pregnancy, including ectopic pregnancy, and the noted protection against endometrial and ovarian cancers, COC use provides other health benefits including preventing and treating menstrual abnormalities (bleeding problems and pelvic pain), reduced risk of symptomatic pelvic inflammatory disease (PID) (although there is no protection against lower genital tract infections and HIV infection), reduced risk of benign breast cysts, reduced risk of iron deficiency anemia, and treatment of acne. While low-dose contraceptives have not been shown to affect the size of preexisting leiomyomata or lead to new ones, they can be effective in controlling menstrual bleeding due to leiomyomata. The protection against ovarian cysts, seen with higher dose COCs, is reduced in low-dose monophasic COCs and may not be present for triphasic COCs.
Return to Fertility after Discontinuing Combined Oral Contraceptives
Women who discontinue COCs have no overall reduction in fertility. There may be a very short delay in time to conception compared with women not using COCs based on the time required to begin ovulating. This delay is temporary, and by 3 to 12 months after discontinuation, there are no differences in fertility rates.
Side Effects
Nausea and breakthrough bleeding are the most common side effects of COC use, although they often diminish or disappear after the first few months of use. Breakthrough bleeding may relate to the specific pill formulation, but it also may be caused by missed pills. If breakthrough bleeding lasts beyond the first 3 months of use, is a problem for the woman, and other gynecologic causes have been ruled out, it may be beneficial to switch to a different COC formulation, typically containing a higher ethinyl estradiol dose. Other approaches to managing breakthrough bleeding include adding concurrent oral estrogen (1.25 mg conjugated equine estrogen or its equivalent, daily for 1 week at the time the breakthrough bleeding occurs), doubling up on active pills for 2 or 3 days until the breakthrough bleeding stops, doubling up on active pills through the end of the cycle, or using active pills in a continuous regimen. Nonsteroidal anti-inflammatory drugs (NSAIDs) may also help alleviate breakthrough bleeding. Other common side effects associated with COCs are breast tenderness and headaches. Weight changes are reported frequently, but most recent studies suggest that little, if any, weight gain can be attributed to COC use.
Choices for Pill Initiation
Standard regimens for pill initiation include the following:
Sunday Start: In this commonly used regimen, the woman is counseled to begin the active pills on the first Sunday after her menses begins. If her menses begins on a Sunday, she should start her pills that day. The advantage to this approach is that the woman will likely not be on her menses over the weekend. Alternatively, disadvantages include not being able to get prescriptions filled on weekends.
Thursday Start: With the newly approved 24-day active pill/4-day placebo regimens, a Thursday start will accomplish the same goal of no menses on the weekend.
First-day Start: This approach has the woman start her active pills on the first day of her menses, as long as she has a normal cycle and has no concern of being pregnant.
Quick Start: With the quick-start method, the patient begins taking the pills on the first day of her office visit, as long as she is not pregnant. She should be counseled to use a back-up method for the first 7 days and be informed that her menses will be delayed until she completes the active pills in the pack. This method does not lead to increased spotting or bleeding. In addition, this method helps women to start and continue the pill as they avoid complex counseling regarding pill initiation. In one study, 25% of women counseled for Sunday or menstrual start did not initiate their COCs as prescribed for reasons such as an interim pregnancy, failing to fill the prescription, or misunderstanding instructions.
TABLE 32.2 World Health Organization Medical eligibility Criteria for Contraceptive Use | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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