The Importance of Contraception
Andrew M. Kaunitz
Table Of Contents
Andrew M. Kaunitz, MD
BENEFITS OF EFFECTIVE CONTRACEPTION|
MAJOR EVENTS IN BIRTH CONTROL IN THE UNITED STATES
CURRENT CONTRACEPTIVE USE AND UNINTENDED PREGNANCIES IN THE UNITED STATES
COMPARISON OF CONTRACEPTIVE EFFICACY, COSTS, AND BENEFITS
|BENEFITS OF EFFECTIVE CONTRACEPTION|
With the chapters in this volume that address specific contraceptive methods and issues, this introductory chapter provides an overview of the overall benefits of birth control, details contraceptive practices (particularly among US women), and concludes by comparing the efficacy, costs, and benefits of existing as well as emerging reversible contraceptives.
By reducing unintended pregnancies and abortions, and facilitating family planning/spacing of births, effective contraception provides both health and social benefits to mothers and their children. According to worldwide estimates, some 600,000 women die each year of pregnancy-related causes, and 75,000 die following unsafe abortions.1 At least 200,000 of these maternal deaths are attributable to the failure or lack of contraceptive services.2 In addition to preventing mortality, effective contraception improves maternal health. Data from the well-controlled Intergenerational Panel Study of Mothers and Children, a 31-year longitudinal survey of 1113 mother-child pairs, indicate that unwanted births can lead to nonpsychotic major depression (postpartum depression), feelings of powerlessness, increased time pressures, and a reduction in overall physical health.3 Finally, effective contraception improves the social and economic role of women and enables them to participate in society fully.4,5
Infants and children also derive benefits from effective contraception. As modern contraceptive methods have become more widely available throughout the world, infant mortality has decreased from approximately 150 deaths per 1000 live births in the 1950s to 80 deaths per 1000 live births in the 1990s.4 In developing countries, 53% of married women plan family size, and 90% of them use modern birth control methods such as female sterilization, oral contraceptives (OCs), and intrauterine devices (IUDs).4 According to Population Action International, infant mortality in developing countries could be decreased by one third by increasing the spacing between births to 2 to 4 years.1 The health status of infants and children is also improved as the result of effective contraception. In the 31-year mother-child survey, unwanted children had more health problems, such as lower birth weight and higher mortality, than those who had been wanted.3 Mothers who had an unwanted birth also had a poorer quality relationship with all their children, tending to spank them more and spend less leisure time with them.3 In addition, evidence indicates that children from large families generally receive less education.1
|MAJOR EVENTS IN BIRTH CONTROL IN THE UNITED STATES|
Key events in the availability of modern contraceptive in the United States are summarized in Table 1.4,6 Although many refer to these events as the contraceptive revolution, Diczfalusy recently observed that “many scientists wonder whether or not contraception is still a revolution or rather a normal way of life—with significantly improved quality of life-for a billion couples.”7 Condoms have been available for hundreds of years, yet most major advances in contraception have occurred since the 1960s and 1970s.6 OCs and IUDs were introduced in the early 1960s, and both had become highly popular methods of contraception by the 1970s, as use of the diaphragm and male condom waned.6,8 However, the 1980s saw a dramatic decrease in IUD use as the result of concerns about intrauterine infections.4,8 Today, only 0.8% of US women use IUDs compared with nearly 100 million women worldwide.6 Major changes occurred during the 1990s as condom use among adolescents increased, probably because of public health efforts to increase awareness about the risks of human immunodeficiency virus infection and other sexually transmitted diseases (STDs), and OC use decreased slightly.4,9 Additionally, approval of levonorgestrel implants and the depot medroxyprogesterone acetate (DMPA) contraceptive injection provided methods that offered excellent protection in less user-dependent forms.6 In fact, the decline in teen pregnancies seen in the last decade has been attributed largely to increased use of DMPA.10
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|CURRENT CONTRACEPTIVE USE AND UNINTENDED PREGNANCIES IN THE UNITED STATES|
The 1995 National Survey of Family Growth (NSFG) provides the most current definitive data on the contraceptive methods used by US women aged 15 to 44 years. As shown in Figure 1, female and male sterilization and OCs account for 65% of contraceptive usage.9 DMPA, levonorgestrel (Norplant), and IUDs account for another 5% of contraceptive use. Therefore, 30% of US women are not using effective contraceptive methods.
In both Canada and the United States, a substantial percentage of those desiring contraception rely on male or female sterilization, whereas in France, only 3% of women use female sterilization and male sterilization is virtually nonexistent (Table 2).9,11,12 The percentage of US women who rely on the male condom as their contraceptive method is twice that in either Canada or France. Fewer than 30% of US women and fewer than 20% of Canadian women use OCs as their contraceptive method. France is unique among these developed countries, with its fairly high level of OC use, even among older women, and of IUD use, and its low use of female sterilization. Access to female sterilization is limited in France and in many developing nations.12 In less developed countries, the IUD is the most popular modern reversible contraceptive method, followed by the male condom.2 However, in more developed regions, the OC is the most popular method of birth control, followed by the male condom and then by the IUD.2
Despite the many advances made in contraception, access to a wide range of method choices is limited, even in developed countries. When nations were ranked according to the availability of six contraceptive methods (male sterilization, female sterilization, OCs, IUDs, injectables, and condoms) in 1996, the United States ranked sixth as a result of low availability of the IUD (Fig. 2).1
Likewise, Italy and France ranked tenth and eleventh because of limited access to sterilization, and Japan ranked last because at that time OCs were not available. Lack of an adequate variety of contraceptive choices has a direct impact on the percentage of couples who use any method. Data from 36 developing countries indicate that when only one or two methods are available, the prevalence of contraceptive use is lower than 30%, whereas when five or six methods are available, use increases to more than 60%.2
High Rates of Sterilization in US Women
In the United States, couples have compensated for the lack of contraceptive choices by increased reliance on voluntary sterilization.13 According to estimates for women from the 1995 NSFG and for men from the 1987–1988 National Survey of Family Households (NSFH), three quarters of all intact marriages rely on sterilization as the contraceptive method.14 Based on data from the National Hospital Discharge Survey for the period from 1970 to 1995, Westhoff and Davis estimate that 11 million US women aged 15 to 44 years rely on tubal sterilization for contraception.15 Each year in the United States, 700,000 sterilization procedures are performed; half these are done as outpatient procedures.15
Those who opt for surgical sterilization to prevent pregnancy believe that the method is “foolproof” when, in fact, failure rates across all types of procedures have been underestimated at 0% to 0.4%.16 The US Collaborative Review of Sterilization (CREST), a multicenter, prospective cohort study that included a total of 10,685 women who underwent tubal sterilization between 1978 and 1986 at 16 US medical centers, found 10-year cumulative rates ranging from 7.5 to 1000 for unipolar coagulation and postpartum partial salpingectomy to 36.5 to 1000 with spring clip application17 (Table 3). The risk of pregnancy was highest among women who were sterilized at younger ages (28 to 33 years) compared with those sterilized at age 34 years and older.
n, number of women sterilized.
(Adapted from Peterson, HB et al: The risk of pregnancy after tubal sterilization: Findings from the U.S. Collaborative Review of Sterilization. Am J Obstet Gynecol 174:1161---1170, 1996.)
Several factors contribute to the high prevalence of sterilization among US couples. Coverage of costs by health care providers has a major impact on contraceptive choice. A recent survey by the Alan Guttmacher Institute found that 85% to 90% of all managed care plans routinely covered tubal sterilization and vasectomy and at least two thirds covered abortions performed by dilatation and curettage or suction aspiration (Fig. 3).18
None of the reversible contraceptive methods is routinely covered by 49% of typical indemnity plans, and only 15% cover provider costs for all five of the most commonly used methods: IUD, diaphragm, contraceptive implant, injection, and OC. Moreover, although most traditional indemnity plans and preferred provider organizations provide coverage for prescription drugs in general, only about 40% routinely cover the cost of OCs.18 In contrast, coverage for OCs is provided by 84% of health maintenance organizations.
The attention given by the news media to negative reports regarding reversible methods of contraception has also contributed to high use of female sterilization in the United States. According to Philip D. Darney in a conversation in April 2000:
Education also affects contraceptive practices. Data from the 1995 NSFG showed that among non-Hispanic white and non-Hispanic black women aged 22 to 44, use of female sterilization decreased as the woman's years of education increased.9 Among those with less than 11 years of schooling, 50% used female sterilization and 11% used male sterilization. By contrast, among those with at least 13 years' education, 16% used female sterilization and 14% used male sterilization as the contraceptive method. Combined data from the 1995 NSFG and the 1987–1988 NSFH indicate that among couples who chose sterilization, the likelihood of female sterilization relative to vasectomy decreases as the wife's education increases, which is consistent with the expectation that better-educated husbands are more likely to undergo vasectomy.14
Frank provides further insight into the impact that education can have in improving use of reversible contraceptive methods.19 A comparison of data on contraceptive use from the 1993–1994 Women Physicians' Health Study, which included female physicians aged 30 to 44 and the general population of women aged 15 to 44 (1990 NSFG) showed that overall, female physicians were more likely to use contraception than higher income nonphysicians (73% versus 64%).
As shown in Figure 5, compared with the general population of higher income women, female physicians were five times more likely to use IUDs (5% versus 1%), more likely to use diaphragms (18% versus 4%) and condoms (20% versus 17%), and less likely to use tubal sterilization (12% versus 25%) or vasectomy (10% versus 16%). Compared with other female physicians, obstetrician/gynecologists were more likely to use OCs, diaphragms, and IUDs and less likely to rely on male or female sterilization. However, Frank notes that the comparisons may have been biased by the lower fecundity and higher rates of marriage of these female physicians. Sterilization is not an appropriate contraceptive method until careful consideration has been given to irrevocably ending childbearing potential.
Unintended Pregnancy and Abortion
Numerator for rates includes women aged 40 and older; denominator includes women aged 40---44.
(Adapted from Henshaw SK: Unintended pregnancy in the United States. Fam Plan. Perspect 30:24---29 & 46, 1998.)
The highest rates of unintended pregnancies and births occurred in teens (ages 15 to 19) and young women (ages 20 to 24), followed by older reproductive-age women at least 40 years of age (Fig. 6). However, compared with 1987, the rate of unintended pregnancies in 15- to 19-year-olds declined from 79.3 in 1000 women to 71.1 to 1000 women.21 This decline is attributable primarily to increased use of long-acting hormonal contraception by teenagers.4,9
The rate of unintended births in the United States is similar to those in Canada, which has comparable contraceptive access, and higher than that in Sweden where a greater number and variety of contraceptive methods are available (see Fig. 2).1,4,21,22 However, the abortion rate in the United States is higher than that of other developed countries as well as many less-developed nations (Fig. 7).21,22 For example, according to recent statistics, the abortion rate per 1000 women aged 14 to 44 years was 6.5 in the Netherlands and 20 to 22.9 in the United States.23 With its heavy reliance on abortion and sterilization to limit family size, the United States resembles a less developed country more than it does other industrialized nations, such as Germany or Canada.
|COMPARISON OF CONTRACEPTIVE EFFICACY, COSTS, AND BENEFITS|
As shown in Figure 8, contraceptive methods with high first-year failure rates during typical use are periodic abstinence, withdrawal, male condoms, diaphragms, and spermicides.24,25 Highly effective methods with low first-year failure rates during typical use include copper or progesterone-bearing IUDs, OCs, implants, injectables, and sterilization.
The results of a recent 60-week, US multicenter, controlled, nonrandomized, parallel study in which 1103 women used either a monthly contraceptive injection containing MPA and estradiol cypionate (E2) (Lunelle, n = 782) or an OC-containing triphasic norethindrone (NET) and ethinyl estradiol (Ortho-Novum 7/7/7, n = 321) demonstrate the high effectiveness that can be achieved with reversible contraceptives.26 In this trial, one unintended pregnancy was reported at the third visit in a patient receiving the OC and no pregnancies occurred during 13 cycles of 28 days in study subjects receiving monthly injections. Pregnancy rate estimates using Pearl index and life-table methods were 0.0 and 0.0, respectively, with the monthly injection and 0.3 and 0.4, respectively, with the OC. Thus, both the monthly injections and the OC provided a high degree of contraceptive efficacy. Because this was a clinical trial, participants were highly motivated (and monitored). Accordingly, higher failure rates are observed in routine clinical practice. Increased use of these and other highly effective methods of contraception by US women would decrease rates of unintended pregnancy and induced abortion.
Effective methods of contraception are also highly cost-effective (Fig. 9).27 In an analysis in the managed care payment model, 5-year costs associated with reversible methods increase as the effectiveness of the method decreases; nearly all cost with less effective methods is related to unintended pregnancy rather than method acquisition.27 With the highest cost-effective reversible methods—copper-T IUD, implants, and injectables—method acquisition accounts for most of the cost. Costs of barrier methods are increased by unintended pregnancy. Among permanent methods of contraception, female sterilization is less cost effective than vasectomy as the result of the greater cost of tubal sterilization, including operating room and anesthesia requirements.
Characteristics of highly effective, reversible contraceptive methods are compared in Table 5. Several comments are warranted with regard to differences in benefits and risks associated with these methods. In terms of major risks, OCs are known to have procoagulant effects related to the estrogen component. Such procoagulant changes increase users' risk of deep vein thrombosis. Although procoagulant effects were most pronounced with high estrogen-dose OC formulations, mild procoagulant effects within the normal range have been reported with formulations containing 35 μg or less of estrogen.13 Unlike OCs, DMPA does not increase globulin production in the liver and is not associated with increases in procoagulant factors.28 No procoagulant changes are seen with either levonorgestrel implants or the copper IUD.28
OC, oral contraceptives; DMPA, depot medroxyprogesterone acetate.
(Adapted from Kaunitz AM: Injectable contraception: New and existing options. Obstet Gynecol Clin North Am 27:741---780, 2000.)
Another concern with hormonal methods of contraception is their impact on bone mineral density (BMD). Several studies of OCs, DMPA, and levonorgestrel implants have examined changes in BMD. A history of OC use was found to be protective against low BMD in a US cross-sectional study.29 In a large Swedish case-control study, OC use by women age 40 and older was associated with a 25% reduction in postmenopausal hip fracture risk.30 Studies have found the OC use has a protective effect against osteopenia in young, reproductive-age women with hypoestrogenic conditions (e.g., hypothalamic amenorrhea or anorexia nervosa), and helps maintain BMD in older reproductive-age women with declining ovarian function.31 Available data suggest that use of levonorgestrel implants may have a neutral or beneficial effect on BMD.32
The impact of current or past use of DMPA on BMD has been the addressed by 13 studies.28 Overall, current use of DMPA appears to be associated with a decrease in BMD that is reversible following cessation of use and therefore unlikely to have clinical importance. A New Zealand study found that postmenopausal bone mineral density in former DMPA users was not significantly different from that of never-users at any site.33 In this regard, the impact of DMPA on bone density resembles that of lactation in that both lower ovarian production of estradiol, leading to reversible declines in BMD.28
In contrast to implants and the copper IUD, both OCs and DMPA have many well-established noncontraceptive benefits. Both OCs and DMPA prevent iron-deficiency anemia, ectopic pregnancy, pelvic inflammatory disease, and endometrial cancer.34,35 Additional noncontraceptive benefits of OCs include protection from dysmenorrhea and menorrhagia, ovarian cysts, benign breast disease, and ovarian cancers, emerging benefits such as the treatment of acne and dysfunctional uterine bleeding, and the prevention of osteopenia and osteoporotic fractures.30,34,36 An additional noncontraceptive benefit of DMPA is a reduced need for hysterectomy in women with uterine leiomyomata.35
Protection against STDs represents a critical issue for reproductive-age women. Because the trend toward initiating sexual activity at a younger age and postponing marriage until an older age places women at increased risk for both unintended pregnancy and STDs, clinicians should try to encourage use of contraceptive options that achieve both goals. However, as shown in Table 6, the most effective reversible contraceptive methods (DMPA, implants, IUDs and OCs) do not protect users against STDs, whereas a method with relatively low contraceptive efficacy—the male condom—provides the greatest STD protection.37
HPV, human papillomavirus; HIV, human immune deficiency virus; IUD, intrauterine device. HSV, herpes simplex virus; DMPA, depot medroxyprogesterone acetate.
(Adapted from Cates W Jr, Sulak PJ: Contraceptives and STDs: Alternative approaches to providing dual protection. Dialog Contracept 6:1---4, 9, 2000.)
Providing the dual benefits of protection against pregnancy and STDs is a particularly vexing challenge among adolescents. Clinicians have noted that long-acting hormonal preparations such as DMPA or levonorgestrel represent better options than OCs for pregnancy prevention in this age-group because they remove need for daily compliance.38 However, a recent study in urban teens found that those using levonorgestrel were less likely to report condom use at last sexual contact or consistent condom use at follow-up 1 or 2 years later than users of OCs or condoms.39 These findings suggest that both the sexual behavior and motivation to use condoms in teens who use implants differ from those of teens who use OCs and condoms. In addition, teens often fail to use OCs or condoms in a fashion sufficiently consistent to prevent either unintended pregnancy or STDs.
Contraceptive methods that may be available in the United States in the near future are described in Table 7. These include a monthly injection containing medroxyprogesterone acetate/estradiol cypionate (MPA/E2C, Lunelle, a two-rod levonorgestrel subdermal implant (Norplant-II), a one-rod etonorgestrel implant (Implanon), an IUD that releases levonorgestrel 20 μg/day for up to 7 years (LNG-20 IUD, Mirena), a vaginal ring that releases etonorgestrel and ethinyl estradiol (NuvaRing) and is discarded after 3 weeks to allow menses, and a 1-week transdermal patch that releases 17-desacetylnorgestimate and ethinyl estradiol (EVRA). A US company has also announced its intentions to reintroduce the Today contraceptive sponge impregnated with 1-g nonoxynol-9. Data from clinical trials indicate that the monthly combination injection, the new implants, and the levonorgestrel IUD are highly effective contraceptive methods.1,26 In an open-label, nonrandomized, parallel, controlled study of the MPA/E2C contraceptive injection, no pregnancies occurred among 782 women during the first year of use (13 cycles of 28 days).26 With the two-rod implant, 5-year failure rates of 0.7% were reported in a large clinical trial,40 and the one-rod implant has been shown to be effective for 3 years with no pregnancies in a large number of women.41 A 7-year cumulative failure rate of 1.1% has been reported with the LNG-20 IUD.1 The vaginal ring appears to have contraceptive effectiveness considerably higher than the diaphragm, approaching that of OCs.42 However, no published data addressing the contraceptive efficacy of the estrogen-progestin vaginal ring or the transdermal patch are currently available.
LNG, levonorgestrel; IUD, intrauterine device, STD, sexually transmitted disease.
(Adapted from Mishell DR, Arias RD, Darney PD et al: Contraception in the US: New methods = wider choices. Contemp Obstet Gynecol Suppl:1---26, 2000.)
These new contraceptive options will be valuable additions to the menu of contraceptive choices that clinicians can offer their patients. With the monthly combination injection, US women will have a shorter-acting alternative to DMPA. Although monthly injections are required, menstrual cycles are regular and there is a rapid return to fertility following cessation of use. Moreover, because estradiol cypionate does not increase hepatic globulin synthesis, no significant procoagulant effects have been seen in users of the monthly combination injection.28 The new second generation implants are much simpler to insert and remove than the first generation six-rod system, and their initial acceptance by patients and clinicians in many European countries has been excellent.42 Amenorrhea rather than irregular bleeding is generally seen with these products, which is acceptable to an increasing number of US women.42 These improvements may lead to a renaissance of interest in contraceptive implants among US clinicians and patients.
With the LNG-20 IUD, progestin is released more slowly and acts locally on the endometrium.42 Thus, there is less bleeding and indeed often amenorrhea occurs, making this a useful contraceptive option to reduce menstrual blood loss in women with menorrhagia, including those with bleeding dyscrasias. This progestin-releasing IUD also provides endometrial protection in menopausal women using estrogen, with few of the side effects related to systemic progestin use. The vaginal ring releases a low dose of hormones continuously when in place. Although designed to be removed for 7 days after 3 weeks of use, it can remain in place for longer periods, enabling a woman to control the timing of menses. The device is smaller than the diaphragm; because it is a one-size-fits-all product, no fitting is required. The ring should be an attractive contraceptive option for a substantial number of women. Like the vaginal ring, the new estrogen/progestin transdermal patch provides efficacy and cycle control similar to that of OCs without the need for daily pill-taking.42
A dedicated formulation became available in the United States in 1998 for emergency contraception. With Preven, the marketed version of the Yuzpe regimen, two tablets of a 50 μg-estrogen/progestin OC are taken 12 hours apart. Recently, a progestin-only method—Plan B—was approved. With Plan B, two 750-mg tablets of levonorgestrel are taken 12 hours apart. Plan B is reported to be 85% effective with a pregnancy rate of less than 2%.42 An advantage of the progestin-only method is that it causes fewer gastrointestinal side effects than the older method. Today, some clinicians provide every patient at risk for pregnancy with an advance prescription for emergency contraception. This strategy increases the likelihood that women will use emergency contraception when they need it and represents an important tool for reducing unintended pregnancies.
Effective contraception benefits both mothers and children by decreasing morbidity and mortality, improving the social and economic status of women, and improving the relationship of the mother with all her children. Despite the availability of effective, reversible methods of contraception, the United States has rates of unintended pregnancy and abortion more resembling those of a developing country than other industrialized nations. Among US couples, 40% choose male or female sterilization as their method of contraception, whereas in developing nations where access to female sterilization is limited, the IUD is the most popular method. In more developed countries, the OC is the most popular method of birth control, followed by the condom and the IUD.
Heavy reliance on sterilization by U.S. couples reflects the lack of contraceptive choices and the mistaken belief that this surgical method is “foolproof.” In fact, failure rates with various methods of tubal sterilization have been underestimated; this method is no more effective than injections, IUDs, or implants. The negative media attention focused on problems with reversible methods has also contributed to overuse of sterilization. An additional factor is that most health-care plans cover sterilization whereas only 49% of typical indemnity plans cover the cost of OCs, IUDs, diaphragms, or contraceptive implants and injections. Plans that provide coverage of prescription drugs often do not cover OCs.
New contraceptive methods likely to become available in the US soon will increase the number of effective, reversible contraceptive choices for US couples. Greater access to a wider variety of methods will increase contraceptive use. Much as a good cafeteria offers a wide selection of foods to accommodate a variety of tastes, so too, must clinicians be able to offer women safe, effective, convenient options that meet their individual needs and preferences. The availability of a greater number of contraceptive choices will increase the use of more effective methods and thus has the potential to reduce unintended pregnancies and abortions in U.S. women of all ages.
26. Kaunitz AM, Garceau RJ, Cromie MA et al: Comparative safety, efficacy, and cycle control of Lunelle monthly contraceptive injection (medroxyprogesterone acetate and estradiol cypionate injectable suspension) and Ortho-Novum 7/7/7 oral contraceptive (norethindrone/ethinyl estradiol triphasic). Contraception 60: 179– 187, 1999
32. Cromer BA, Blair JM, Mahan JD et al: A prospective comparison of bone density in adolescent girls receiving depot medroxyprogesterone acetate (Depo-Provera), levonorgestrel (Norplant), or oral contraceptives. J Pediatr 129: 671– 676, 1996
33. Orr-Walker BJ, Evans MC, Ames RW et al: The effect of past use of the injectable contraceptive depot medroxyprogesterone acetate on bone mineral density in normal post-menopausal women. Clin Endocrinol 49: 615– 618, 1998
36. Davis A, Lippman J, Godwin A et al: Triphasic norgestimate/ethinyl estradiol oral contraceptive for the treatment of dysfunctional uterine bleeding. Obstet Gynecol 95 (Suppl 1): S84, 2000
39. Darney PD, Callegari LS, Swift A et al: Condom practices of urban teens using Norplant contraceptive implants, oral contraceptives, and condoms for contraception. Am J Obstet Gynecol 180: 929– 937, 1999
41. Zheng S-R, Zheng H-M, Qian S-Z et al: A randomized multicenter study comparing the efficacy and bleeding pattern of a single-rod (Implanon) and a six-capsule (Norplant) hormonal contraceptive implant. Contraception 60: 1– 8, 1999