New Contraceptive Options EMILY J. HERNDON, M.D., and MIRIAM ZIEMAN, M.D. Emory University School of Medicine, Atlanta, Georgia Almost one half of pregnancies in the United States are unintended. Primary reasons for the high rate of unplanned pregnancy include dissatisfaction with or underuse of effective contraceptive methods and poor compliance with contraceptive methods that require daily adherence. Several effective forms of contraception have become available in the United States within the past four years. The combined hormonal vaginal ring is inserted into the vagina for three weeks and then removed; after one ring-free week, a new ring is inserted. The contraceptive patch works in much the same way as oral contraceptive pills but requires only once-weekly application by the patient. A new intrauterine system that releases levonorgestrel provides the same contraception as traditional intrauterine devices but is associated with less menorrhagia and dysmenorrhea. The intrauterine system is highly effective and carries minimal risk of pelvic inflammatory disease. In providing counseling about contraception, the physician should consider the woman's preference and determine the likelihood of adherence to the regimen. In case of contraceptive failure, emergency contraception is effective. (Am Fam Physician 2004;69:853-60. Copyright 2004© American Academy of Family Physicians.)

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Approximately 49 percent of pregnancies in the United States are unintended.¹ One cost analysis² found that compared with pregnancy and abortion, contraception saves an estimated $9,000 to $14,000 per woman of childbearing age over a five-year period. Although some methods of contraception have side effects, morbidity and mortality rates are significantly higher for pregnancy and childbirth than for the use of any contraceptive method alone.³

See page 922 for definitions of level-of-evidence labels. See editorial on page 811.

Oral contraceptive pills (OCPs), male condoms, and female sterilization are the contraceptive methods most commonly used in the United States.⁴ However, approximately 3 million U.S. women at risk for unintended pregnancy are using no form of contraception.⁵ Frequently cited reasons for discontinuing a method when contraception is still desired include side effects, difficulty of use, safety concerns, and lack of access to health care.⁵ Furthermore, personal beliefs and preferences influence a woman's willingness to use a contraceptive method correctly.

Family physicians provide contraceptive counseling to a significant number of patients each year. Knowledge of the wide variety of contraceptive methods and barriers to the use of some of these methods is important in helping each patient make an appropriate choice.

Traditional Methods of Contraception

The benefits, side effects, and potential complications of traditional methods of contraception are reviewed in detail elsewhere.^6-8 A summary of these methods is provided in Table 1.^8-11

It is important to note certain changes that have occurred in the past several years. For example, no contraceptive sponges currently are available in the United States, although a new vaginal sponge (Protectaid) is under investigation. Likewise, the levonorgestrel implant system marketed as Norplant is no longer being manufactured; however, a single-rod implant (Implanon), presently used outside the United States, may become available in the future.

A combination OCP that contains the new progestogen drospirenone (Yasmin) has been available for several years. Drospirenone has some antimineralocorticoid activity and has been shown to decrease the water retention, negative affect, and appetite changes that commonly are associated with menstrual cycle changes.¹² [Strength of Recommendation (SOR) B, descriptive studies and lower quality clinical trials] Serum potassium levels should be monitored when women use this OCP in conjunction with other medicines that also raise potassium levels, because hyperkalemia is a potential side effect.

Finally, studies on the length of time that active pills are given have provided more options and flexibility for OCP users.¹³ The U.S. Food and Drug Administration (FDA) recently approved the use of levonorgestrel­ ethinyl estradiol (Seasonale) in an extended OCP regimen consisting of 84 days of active pills and seven days of nonhormonal pills.

TABLE 1 Traditional Contraceptive Methods Method Side effects Noncontraceptive benefits Potential complications Oral contraceptive pills Nausea, headaches, dizziness, spotting, weight gain, breast tenderness, chloasma Decreases menstrual pain, premenstrual syndrome, and blood loss; protects against symptomatic PID,8 some cancers (ovarian, endometrial), some benign tumors (leiomyomata, benign breast masses), and ovarian cysts; reduces acne. Cardiovascular complications (stroke, heart attack, blood clots, high blood pressure), depression, hepatic adenomas; possible increased risk of breast and cervical cancers IUD Menstrual cramping, spotting, increased bleeding Copper-containing IUDs may provide protection against endometrial cancer9; progesterone-releasing IUDs decrease menstrual blood loss and pain. PID (following insertion), uterine perforation, anemia Male condom Decreased sensation, allergy to latex, loss of spontaneity Protects against STDs, including HIV infection; delays premature ejaculation. Anaphylactic reaction to latex Female condom Aesthetically unappealing; for some women, awkward to use Protects against STDs. None known Hormonal implant Tenderness at implant site, menstrual changes, hair loss, weight gain Does not disturb lactation; may decrease menstrual cramps, pain, and blood loss. Infection at implant site, complicated removal, depression Progestin-only injections Menstrual changes, weight gain, headaches, adverse effects on cholesterol levels (i.e., decreases high-density lipoprotein cholesterol level) Does not disturb lactation; reduces risk of seizures; may have protective effects against PID, as well as ovarian and endometrial cancers. Depression, allergic reactions, pathologic weight gain; possible bone loss Female sterilization Pain at surgical site; psychologic reactions, including regret that procedure was performed Reduces risk of ovarian cancer; may protect against PID.10 Infection, anesthetic complications; if pregnancy occurs after tubal ligation, high risk of ectopic pregnancy Abstinence Psychologic reactions Prevents STDs, including HIV infection. None known Barrier contraceptives: diaphragm, cervical cap, vaginal sponge Pelvic pressure, vaginal irritation, allergy; vaginal discharge if left in too long Provides modest protection against some STDs. Vaginal and urinary tract infections, toxic shock syndrome Spermicides Vaginal irritation, allergy Provides modest protection against some STDs; potential increased risk of HIV infection with use of nonoxynol-911 Vaginal and urinary tract infections Lactational amenorrhea Mastitis from staphylococcal infection Breastfeeding has nutritional benefits for infant. Increased risk of HIV transmission to infant if mother is HIV positive PID = pelvic inflammatory disease; IUD = intrauterine device; STD = sexually transmitted disease; HIV = human immunodeficiency virus. Information from references 8 through 11.

Newer Methods of Contraception

Traditional methods of contraception have some drawbacks (Table 1).^8-11 Consequently, patient dissatisfaction and inconsistent or incorrect use may result in unintended pregnancy. For example, the success of OCPs, the most widely used reversible contraceptive method, is highly dependent on daily adherence. In one study,¹⁴ approximately 47 percent of OCP users failed to take one or more pills per cycle, and 22 percent failed to take two or more pills.

In designing the newer contraceptives, attention has been given to improving the side effect profiles of older methods and to developing delivery systems that do not require daily patient adherence.

VAGINAL CONTRACEPTIVE RING

The vaginal contraceptive ring, which releases 15 mcg of ethinyl estradiol and 120 mcg of etonogestrel per day, remains in the vagina for three weeks and then is removed. After one ring-free week, a new ring is inserted.

The combined hormonal vaginal ring (NuvaRing) has a unique delivery system. The ring works in a similar manner as OCPs, but daily action by the patient is not required. The ring (Figure 1), which releases ethinyl estradiol at a rate of 15 mcg per day and etonogestrel at a rate of 120 mcg per day, is placed in the vagina for three weeks. If for some reason the ring is out of the vagina for more than three hours, back-up contraception should be used until the ring has been back in place for seven days. After three weeks, the ring is removed for one week, and a new ring is inserted. Withdrawal bleeding occurs during the ring-free week.

In a one-year study,¹⁵ the overall failure rate for the vaginal ring was 0.65 pregnancies per 100 women-years. The majority of women in the study considered insertion and removal of the vaginal ring to be easy, and 90 percent used the device correctly. Adverse effects that led to discontinuation of vaginal ring use most often were related to foreign body sensation, coital problems, and expulsion of the device. However, only 3.6 percent of women in the study stopped using the device for these reasons.

FIGURE 1. Vaginal ring (NuvaRing). The circular ring is flexible and easily inserted into the vagina. Unlike the diaphragm, the vaginal ring does not have to be in a specific position, because absorption of the hormones can occur anywhere in the vagina. Photograph used with permission of Organon Inc., West Orange, N.J.

In terms of cycle control, the vaginal ring is associated with a lower incidence of breakthrough bleeding than levonorgestrel­ethinyl estradiol OCPs, and with a higher rate of normal withdrawal bleeding.¹⁶

COMBINED HORMONAL INJECTION

The combined hormonal injection, which contains 25 mg of medroxyprogesterone acetate and 5 mg of estradiol cypionate, is another method of contraception that does not require daily adherence. Unlike progestin-only preparations, this injection is given monthly. The combined hormonal injection is available outside the United States. Although approved by the FDA, the combined hormonal injection currently is not being manufactured in this country, and its future availability is unknown.

Clinical trials have shown this contraceptive method to be highly effective, with life-table failure rates of zero to 0.2 pregnancies per 100 women-years.¹⁷ Because of the added estrogen, bleeding patterns usually are regular and comparable with the bleeding patterns occurring with combination OCPs.¹⁸

CONTRACEPTIVE PATCH

In 2002, the FDA approved the use of a combination contraceptive patch (Ortho Evra) that releases 20 mcg of ethinyl estradiol and 150 mcg of norelgestromin per day. It inhibits ovulation in much the same way as OCPs. The patch is applied weekly for three weeks, followed by a patch-free week during which withdrawal bleeding occurs. Recommended application sites include the upper arm, buttocks, lower abdomen, and upper torso (excluding the breasts).

The overall failure rate for the contraceptive patch has been reported to be only 0.88 pregnancies per 100 women-years, with a method failure rate of 0.7 pregnancies per 100 women-years. However, this form of contraception may be less effective in women weighing more than 90 kg (198 lb).¹⁹

Compliance with combination contraceptive patch use has been shown to be significantly greater than compliance with oral contraceptive pill use.

In a study²⁰ comparing the contraceptive patch and OCPs, spotting occurred at a higher rate in the first two months of patch use. However, spotting rates for the two contraceptive methods were similar in subsequent cycles. A key finding in this study was that compliance was significantly greater with patch use than with OCP use. Although adverse event rates were similar with both contraceptive methods, application site reactions were unique to the patch, and breast discomfort was more common in the first two months of patch use. Finally, the study showed that patch adhesion appears to be reliable, with only 2.8 percent of the patches partially detaching and 1.8 percent completely detaching.

LEVONOGESTREL INTRAUTERINE SYSTEM

FIGURE 2. Intrauterine system (Mirena). This system differs from the traditional copper-containing intrauterine device in appearance and mechanism of action. The arms fold up rather than down, and the insertion technique is slightly different. Photograph used with permission of Berlex Laboratories, Wayne, N.J.

The FDA recently approved the use of an intrauterine system (Mirena) that releases 20 mcg of levonorgestrel per day and provides effective contraception for at least five years (Figure 2). This intrauterine system has been shown to be as effective as copper-containing intrauterine devices (IUDs).²¹ [SOR A, systematic review of randomized controlled trials (RCTs)] Pregnancy rates are comparable with those occurring with surgical sterilization.²²

Although copper-containing IUDs can increase bleeding and dysmenorrhea, the levonorgestrel system actually lessens these symptoms.²¹ The typical bleeding profile with the new intrauterine system is irregular bleeding or spotting for the first six months of use, followed by very light menses, with 20 percent of women having amenorrhea at one year of use. The amenorrhea results from the local action of levonorgestrel, which creates an atrophic endometrium. Because estradiol levels are maintained, osteopenia is not associated with this contraceptive method.

Because of the safety profile of the new intrauterine system and the high rates of oligomenorrhea and amenorrhea, the system currently is being evaluated for use in conditions such as dysfunctional uterine bleeding.⁹

Only minimal side effects have been found with the intrauterine system.²³ As with copper-containing IUDs, there is a risk of expulsion and ectopic pregnancy. Side effects unique to the levonorgestrel system have been related to the hormonal component and include a slight increase in the rates of headaches and acne.²¹

The levonorgestrel intrauterine system appears to be associated with an even lower rate of pelvic inflammatory disease than the copper-containing intrauterine device.

Recent data indicate that copper-containing IUDs are associated with lower rates of pelvic inflammatory disease (PID) and infertility than was previously thought.^24,25 Evidence suggests that the risk of PID is even lower with the levonorgestrel system.²³ [Strength of recommendation: A,RCT]

The new intrauterine system and the standard copper-containing IUD are inserted using different devices. Hence, attention to technique is important. The levonorgestrel system costs significantly more than the standard IUD. Note that the copper-containing IUD has been shown to be the most cost-effective method of birth control at two years.²

Contraceptive Counseling

A brief overview of current contraceptive options is provided in Table 2.^8,11,26,27 When counseling a patient about contraceptive methods, the family physician should be aware that the only effective contraceptive for any patient is the one that the patient is willing to use consistently and correctly. Ultimately, the patient is the one who must decide on the method of contraception; this decision often will be based on the patient's personal beliefs, preferences, and specific needs at the time. If needs change, a patient may want to switch to a different method of contraception. The physician's role is to educate the patient about the advantages and disadvantages of each contraceptive method that is medically appropriate for that patient and then allow the patient to choose the most desirable method.

TABLE 2 Overview of Contraceptive Options Currently Available in the United States Unintended pregnancies within first year of use (%)26           Method Typical use* Perfect use† Women continuing use at one year (%)26 Frequency of use Protection against STDs8 Use while breastfeeding8 Cost‡ None 85 85 -- -- -- -- -- Spermicide 29 15 42 Each time No§ Yes $ 0.35 to 12 Withdrawal 27 4 43 Each time No Yes None Periodic abstinence                  Calendar method 25 9 ~ 50 Each time No Yes None    Ovulation method 25 3 ~ 50 Each time No Yes None    Symptothermal method || 25 2 ~ 50 Each time No Yes None    Postovulation method 25 1 ~ 50 Each time No Yes None Cervical cap: parous women¶ 32 26 46 Each time No Yes 30 to 40 Cervical cap: nulliparous women¶ 16 9 57 Each time No Yes 30 to 40 Diaphragm¶ 16 6 57 Each time Yes# Yes 30 to 40 Female condom 21 5 49 Each time Yes Yes 2 to 3 each Male condom 15 2 53 Each time Yes Yes 0.50 to 2 each OCPs 8 0.3 68 Taken daily No **†† 20 to 50 per cycle Contraceptive patch Unknown 0.3 68 Applied weekly No ** 36 per month Vaginal ring Unknown 0.3 68 Inserted every 4 weeks No ** 43 per month Progestin-only OCPs 3 0.3 56 Given every 12 weeks No Yes 30 to 35 every 3 months‡‡ Copper-containing IUD 0.8 0.6 78 Inserted every 10 years No Yes 250 to 300 every 10 years§§ Levonorgestrel intrauterine system 0.1 0.1 81 Inserted every 5 years No Yes 300 to 400 every 5 years§§ Female sterilization 0.5 0.5 100 Done once No Yes 1,200 to 2,500|||| Male sterilization 0.15 0.10 100 Done once No Yes 250 to 1,000 STD = sexually transmitted disease; OCP = oral contraceptive pill; IUD = intrauterine device; HIV = human immunodeficiency virus. *--Among typical couples who initiate use of a method (not necessarily for the first time), the percentage who experience an accidental pregnancy during the first year if they do not stop use for any other reason. †--Among couples who initiate use of a method (not necessarily for the first time) and who use it perfectly (both consistently and correctly), the percentage who experience accidental pregnancy during the first year if they do not stop use for any other reason. ‡--Cost information for spermicide, cervical cap, diaphragm, progestin-only injections, female and male sterilization, condoms, OCPs, IUD, and levonorgestrel intrauterine system from reference 8; cost information for contraceptive patch, vaginal ring, and combined hormonal injection based on average prices in a survey conducted in the authors' area (prices may vary according to region). §--Possible decrease in human papillomavirus transmission but no protection against HIV infection, gonorrhea, and chlamydial infection; potential increase in HIV transmission with use of nonoxynol-9.11 ||--Cervical mucus (ovulation) method supplemented by calendar method in preovulatory phase and by basal body temperature method in postovulatory phase. ¶--Method used with spermicide. #--May protect against gonorrhea, chlamydial infection, cervical dysplasia, and pelvic inflammatory disease; protection against HIV infection cannot be assumed. **--At less than six weeks postpartum, all estrogen-containing contraceptives should be avoided; although use between six weeks and six months postpartum is not contraindicated, there is concern that estrogen-containing contraceptives may decrease the quantity of breast milk.27 ††--Can breastfeed if taking progestin-only OCPs. ‡‡--Excludes cost of office visit for injection (cost may vary according to region). §§--Excludes cost of office visit for insertion (cost may vary according to region). ||||--Estimate for sterilization by minilaporatomy. Adapted from Hatcher RA. A pocket guide to managing contraception. 5th ed. Tiger, Ga.: Bridging the Gap Foundation, 2000-2003:36,44-141, with additional information from references 8, 11, 26, and 27.

Many patients who use contraception have medical conditions; therefore, it is important to discuss the safety of various contraceptive methods, because some are contraindicated in certain circumstances. The World Health Organization²⁷ has established medical eligibility criteria for contraceptive use. If a patient's first choice for contraception is contraindicated, the physician should help the patient select an appropriate alternative.

One important consideration is the risk of contracting sexually transmitted diseases (STDs). Many of the contraceptives that have the greatest efficacy in preventing pregnancy provide no protection against STDs, and methods (specifically condoms) that protect against STDs have higher contraceptive failure rates in typical users. In patients at risk for STDs, greater emphasis should be placed on use of a barrier method of contraception, either alone or in combination with another contraceptive method.²⁸

Patients also should be made aware of options for emergency contraception. This topic has been reviewed previously^29,30; however, two products (Plan B and Preven) are now available in the United States. The use of emergency contraception has not been shown to decrease compliance with standard contraceptive methods.³¹

The authors indicate that they do not have any conflicts of interest. Sources of funding: Dr. Zieman is on the speakers' bureaus of Ortho-McNeil Pharmaceutical and Berlex Laboratories.

The authors thank series coordinator Timothy Clenney, M.D., for editorial assistance.

Members of various medical faculties develop articles for "Practical Therapeutics." This article is one in a series coordinated by the Department of Family and Preventive Medicine at Emory University School of Medicine, Atlanta. Guest editor of the series is Timothy Clenney, M.D.

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The Authors

EMILY J. HERNDON, M.D., is assistant professor in the Department of Family and Preventive Medicine at Emory University School of Medicine, Atlanta. She received her medical degree from Emory University and completed a family practice residency at Florida Hospital, Orlando. Dr. Herndon is a fellow of the American Academy of Family Physicians.

MIRIAM ZIEMAN, M.D., is associate professor in the Department of Gynecology and Obstetrics at Emory University School of Medicine, where she is also director of family planning. Dr. Zieman received her medical degree from Albert Einstein College of Medicine of Yeshiva University, Bronx, N.Y. She completed an obstetrics and gynecology residency at Columbia University College of Physicians and Surgeons, New York, N.Y., and a family planning fellowship at the University of California, San Francisco, School of Medicine. Dr. Zieman is a fellow of the American College of Obstetrics and Gynecology.

Address correspondence to Emily J. Herndon, M.D., 131 Superior Ave., Decatur, GA 30030. Reprints are not available from the authors.

REFERENCES

1. Henshaw SK. Unintended pregnancy in the United States. Fam Plann Perspect 1998;30:24-9,46.
2. Trussell J, Leveque JA, Koenig JD, London R, Borden S, Henneberry J, et al. The economic value of contraception: a comparison of 15 methods. Am J Public Health 1995;85:494-503.
3. Kost K, Forrest JD, Harlap S. Comparing the health risks and benefits of contraceptive choices. Fam Plann Perspect 1991;23:54-61.
4. Piccinino LJ, Mosher WD. Trends in contraceptive use in the United States: 1982-1995. Fam Plann Perspect 1998;30:4-10,46.
5. Burkman RT. Compliance and other issues in contraception. Int J Fertil Womens Med 1999;44:234-40.
6. Cerel-Suhl SL, Yeager BF. Update on oral contraceptive pills. Am Fam Physician 1999;60:2073-84.
7. Canavan TP. Appropriate use of the intrauterine device. Am Fam Physician 1998;58:2077-84,2087-8.
8. Hatcher RA. A pocket guide to managing contraception. 5th ed. Tiger, Ga.: Bridging the Gap Foundation, 2002-2003:36,44-141.
9. Hubacher D, Grimes DA. Noncontraceptive health benefits of intrauterine devices: a systematic review. Obstet Gynecol Surv 2002;57:120-8.
10. Pati S, Cullins V. Female sterilization. Evidence. Obstet Gynecol Clin North Am 2000;27:859-99.
11. World Health Organization. WHO/CONRAD technical consultation on nonoxynol-9, World Health Organization, Geneva 9-10 October 2001: summary report. Reprod Health Matters 2002;10:175-81.
12. Parsey KS, Pong A. An open-label, multicenter study to evaluate Yasmin, a low-dose combination oral contraceptive containing drospirenone, a new progestogen. Contraception 2000;61:105-11.
13. Sulak PJ, Kuehl TJ, Ortiz M, Shull BL. Acceptance of altering the standard 21-day/7-day oral contraceptive regimen to delay menses and reduce hormone withdrawal symptoms. Am J Obstet Gynecol 2002;186:1142-9.
14. Rosenberg MJ, Waugh MS, Burnhill MS. Compliance, counseling and satisfaction with oral contraceptives: a prospective evaluation. Fam Plann Perspect 1998;30:89-92,104.
15. Roumen FJ, Apter D, Mulders TM, Dieben TO. Efficacy, tolerability, and acceptability of a novel contraceptive vaginal ring releasing etonogestrel and ethinyl oestradiol. Hum Reprod 2001;16:469-75.
16. Bjarnadottir RI, Tuppurainen M, Killick SR. Comparison of cycle control with a combined contraceptive vaginal ring and oral levonorgestrel/ethinyl estradiol. Am J Obstet Gynecol 2002;186:389-95.
17. Kaunitz AM. Injectable contraception. New and existing options. Obstet Gynecol Clin North Am 2000;27:741-80.
18. Kaunitz AM, Garceau RJ, Cromie MA. 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). Lunelle Study Group. Contraception 1999;60:179-87.
19. Zieman M, Guillebaud J, Weisberg E, Shangold G, Fisher AC, Creasy GW. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Fertil Steril 2002;77(2 suppl 2):S13-8.
20. Audet MC, Moreau M, Koltun WD, Waldbaum AS, Shangold G, Fisher AC, et al. Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive: a randomized controlled trial. JAMA 2001;285:2347-54.
21. French RS, Cowan FM, Mansour D, Higgins JP, Robinson A, Procter T, et al. Levonorgestrel-releasing (20 micrograms/day) intrauterine systems (Mirena) compared with other methods of reversible contraceptives. BJOG 2000;107:1218-25.
22. Fortney JA, Feldblum PJ, Raymond EG. Intrauterine devices. The optimal long-term contraceptive method? J Reprod Med 1999;44:269-74.
23. Andersson K, Odlind V, Rybo G. Levonorgestrel-releasing and copper-releasing (Nova T) IUDs during five years of use: a randomized comparative trial. Contraception 1994;49:56-72.
24. Hubacher D, Lara-Ricalde R, Taylor DJ, Guerra-Infante F, Guzman-Rodriguez R. Use of copper intrauterine devices and the risk of tubal infertility among nulligravid women. N Engl J Med 2001; 345:561-7.
25. Grimes DA. Intrauterine device and upper-genital-tract infection. Lancet 2000;356:1013-9.
26. Hatcher RA. Contraceptive technology. 18th rev. ed. New York: Ardent Media (In press).
27. Improving access to quality care in family planning: medical eligibility criteria for contraceptive use. 2d ed. Geneva: Reproductive Health and Research, World Health Organization, 2000. Accessed January 21, 2004, at: http://www.who.int/reproductive-health/publications/RHR_00_2_medical_eligibility_criteria_second_edition.
28. Cates W Jr, Steiner MJ. Dual protection against unintended pregnancy and sexually transmitted infections: what is the best contraceptive approach? Sex Transm Dis 2002;29:168-74.
29. Wertheimer RE. Emergency postcoital contraception. Am Fam Physician 2000;62:2287-92.
30. Wellbery C. Emergency contraception. Arch Fam Med 2000;9:642-6.
31. Glasier A, Baird D. The effects of self-administering emergency contraception. N Engl J Med 1998;339: 1-4.

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