Unintended pregnancy is a major women's health problem. In the United States, about 50% of all pregnancies are unplanned. This article covers female contraceptive methods, sterilization, and emergency contraception approved for use in the United States

Prescribing contraceptives

The choice of contraceptive method is determined by the woman's health, frequency of sexual activity, number of sexual partners, and desire for permanence, as well as the efficacy of the contraceptive method (Table 1).¹ There are several contraindications for combination hormonal contraceptives. They include previous thromboembolic event or stroke, liver disease, history of estrogen-dependent tumor, undiagnosed abnormal uterine bleeding, hypertriglyceridemia, and smoking in women older than 35 years.²

Women with one or more contraindications should not be prescribed combination hormonal contraceptives. Use of combination contraceptives by diabetic women should be limited to those who do not smoke, are younger than 35 years, and are otherwise healthy. Progesterone injections are safer in women who suffer from migraines, headaches, lupus, sickle cell anemia, hypertension, or diabetes with vascular disease and in those older than 35 years.

Specific screening before prescribing contraceptives is not mandatory. However, patients at risk for high blood pressure should undergo screening before initiating contraception. At the initial visit, a 3-month follow-up is suggested for counseling and reinforcement and then yearly thereafter. Women should be counseled about the efficacy, side effects, and correct methods of use; about the signs and symptoms that require return to the physician; and about protection against sexually transmitted diseases (STDs).

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Mechanism of action of hormonal contraceptives

Hormonal contraceptives include combination estrogen and progestin and progestin only. Estrogen effects include inhibition of ovulation and prevention of follicular maturation through suppression of ovarian steroid production and possibly decreased responsiveness to gonadotropin-releasing hormone. Conversely, progestin leads to changes in the endometrium that make implantation less likely, increased thickness of cervical mucus that makes sperm penetration difficult, and impairment of normal tubal mobility.² Most progestins are derivatives of testosterone and thus have residual androgenic activity. It is this androgenic aspect of progestins that causes many of the side effects and metabolic complications.

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Oral contraceptives

Combination Pills

Regimens

The first hormonal agents contained high doses of estrogen and progestin. Lower doses are as effective and cause fewer side effects, which include headache, breast tenderness, nausea, and hypertension. In particular, lower doses of ethinyl estradiol are associated with less risk of thrombosis. Nowadays, contraceptive pills contain less than 50 µg of ethinyl estradiol; most contain 30 or 35 µg, and the newer ones contain 20 or 25 µg.

Newer progestins with fewer androgenic effects include desogestrel and norgestimate.

In some newer regimens, the patient takes placebo pills for fewer days per month than with older regimens, or the placebo pills have been replaced by low-dose hormone pills. These regimens reduce the number of days of withdrawal bleeding, with the intent of improving contraceptive effectiveness, patient adherence, and patient tolerance and reducing side effects. In other newer regimens, hormonal contraceptives are taken in longer cycles to lengthen the intervals between withdrawal bleeding, or continuously, so that the patient has no bleeding at all.

Ethinyl estradiol/norethindrone (Femcon Fe) has the same active ingredients as Ovcon 35. The difference is that Ovcon 35 pill must be swallowed, whereas Femcon Fe is a spearmint-flavored, chewable tablet. In addition, the placebo pill contains iron.

Ethinyl estradiol/drospirenone (Yasmin) is a combined oral contraceptive containing drospirenone and ethinyl estradiol. Yaz has the same dose of drosperinone as Yasmin but a lower dose of ethinyl estradiol. It contains 24 days of active medication and 4 days of placebo. Drospirenone is a spironolactone analogue with antiandrogenic and antimineralocorticoid properties. The antimineralocorticoid effect of drospirenone reduces water retention and bloating. These agents should not be used in women with hepatic failure, renal insufficiency, or adrenal insufficiency. Women taking nonsteroidal anti-inflammatory agents, potassium-sparing diuretics, angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, or potassium supplements should have their serum potassium levels checked during the first treatment cycle. Yaz is the first and only hormonal contraceptive that has been shown to be effective for the treatment of premenstrual dysphoric disorder.

Loestrin 24 Fe provides 3 more days of active hormonal pills than Loestrin for a total 24 days of active medication followed by 4 days of iron-containing placebo pills.

Levonorgestrel/ethinyl estradiol (Seasonale) is a 91-day oral contraceptive regimen that contains levonorgestrel (progestin) and ethinyl estradiol for 12 weeks (84 days), followed by 1 week of placebo. Women have only four menses per year. Seasonique is the same formulation as Seasonale but with the addition of ethinyl estradiol in a lower dose during the 13th week, without levonorgestrel. This addition may reduce the hormonal withdrawal symptoms such as menstrual migraine and dysmenorrhea that can occur during the placebo week with long-cycle hormonal contraceptives. Women on continuous long-cycle hormonal contraception tend to have more unscheduled bleeding than do women on shorter-cycle regimens.

Ethinyl estradiol/levonorgestrel (Lybrel) is taken in a continuous, noncyclic, 365-day regimen. There is no hormone-free period with this regimen. Therefore, hormone levels remain constant, ovulation is suppressed, and women have no menstrual bleeding. It was recently approved by the U.S. Food and Drug Administration (FDA).

Side Effects, Advantages, and Precautions

Dizziness, weight gain, nausea, spotting, amenorrhea, and breast tenderness are among the most common side effects. There is no inhibition of spontaneity, and the contraceptive effects end after 3 months of stopping the pill. Pills must be taken the same time each day, require a prescription, provide no protection against STDs, and need a barrier method for the first 7 days of use. Certain drugs such as rifampin, amoxicillin, metronidazole, tetracyclines, and cephalexin can decrease the effectiveness of the pills.

Progestin-Only Pills

Progestin-only pills (or minipills) are associated with more breakthrough bleeding than combination pills and have slightly higher failure rates. Irregular bleeding, weight gain, and breast tenderness are the most common side effects. Progestin-only pills are a good option for patients who need to avoid estrogen (Fig. 1). Precautions are similar to those for combined oral contraceptives. Minipills offer less protection against ectopic pregnancy.

Figure 1: Click to Enlarge

Noncontraceptive Benefits of Oral Contraceptives

Oral contraceptives have been successfully used in the treatment of hyperandrogenism, including idiopathic hirsutism and polycystic ovary syndrome. Levonorgestrel-containing preparations can aggravate these problems and should, therefore, be avoided in these cases. Oral contraceptives are also used in the treatment of dysmenorrhea, menorrhagia, hypothalamic amenorrhea, hormone replacement in women with primary hypogonadism, and premenstrual syndrome. They lead to lower risk of iron deficiency anemia caused by increased menstrual flow; ectopic pregnancy in the case of combination contraceptives; ovarian cysts; postmenopausal hip fractures in women who used combined contraceptives in their 30s; benign breast disease; ovarian cancer; and endometrial cancer. Preparations containing low doses of estrogen (20 µg) are often used in perimenopausal women. They help to relieve vasomotor flushing, but symptoms recur during the placebo period.

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Injectable contraception

Depot Medroxyprogesterone Acetate

Depot medroxyprogesterone acetate (DMPA; Depo-Provera) is a progesterone that prevents ovulation in addition to causing changes in cervical mucus and the endometrium. It is given as an injection in the buttocks or upper arm within 5 days after the beginning of the normal menstrual cycle and is repeated every 3 months. It is more effective than oral contraceptives.

Side effects include irregular bleeding, weight gain, headache, mood change, abdominal pain, dizziness, weakness or fatigue, and breast tenderness. After 1 year of use, 50% of women have amenorrhea.³ This is not harmful,³ and periods return shortly after the drug is stopped. Studies released in 2004 show that DMPA is associated with a loss of bone density, resulting in an increased risk of osteoporosis. The bone loss appears not to be reversed when the woman stops taking DMPA. DMPA is not recommended for long-term use and is especially not recommended when patients are still growing.

DMPA is safe, is reversible, maintains spontaneity, and has noncontraceptive benefits similar to those of oral contraceptives. Ovulation is suppressed for at least 14 weeks, so delay of up to 2 weeks in the next injection is acceptable. Women with a lapse of more than 14 weeks should have pregnancy ruled out. There is reduced menstrual cramping and pain, fewer periods, and lower chance of anemia.

Precautions include spotting, especially during the first 3 months, and lack of protection against STDs. Fertility usually returns within 6 to 9 months after stopping but can take up to 18 months.³ Patients on DMPA are advised to exercise and take adequate amounts of calcium. A bone density test may be prudent if DMPA is used for more than 2 years.

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Implantable contraception

As of 2002, Norplant is no longer being manufactured. Women should be encouraged to contact their physician near the end of the 5-year expiration date of their Norplant system.

Single-rod progestin implant (Implanon) is placed subdermally in the inner arm. Contraception is provided by slow release of 68 mg of the progestin etonogestrel, which is initially released at 60 to 70 µg/day, decreasing to 35 to 45 µg/day at the end of the first year, to 30 to 40 µg/day at the end of the second year, and then to 25 to 30 µg/day at the end of the third year.

Side effects include spotting, irregular bleeding, and amenorrhea. Irregular bleeding is the primary reason for discontinuation. Fluid retention, weight gain, and breast tenderness are less common. Potential complications of insertion include infection, hematoma formation, local irritation or rash, expulsion, and allergic reactions. A single case of injury to the branches of the medial antebrachial cutaneous nerve during insertion has been reported. Nerve injury can result in impaired sensibility, severe localized pain, or the formation of painful neuroma.

Insertion is on office procedure done with or without local anesthesia. The rod can be removed at any time, but it must be removed at the end of 3 years. Ovulation resumes shortly after removal.

Correct insertion technique and timing of insertion play major roles in the effectiveness of Implanon. The FDA has mandated that providers undergo special training to place and remove Implanon. Implanon should be inserted between day 1 and day 5 of the menstrual cycle. If done during other days of the menstrual cycle, a pregnancy test must be done. The patient should be advised to use another method of contraception for at least 1 week after insertion.

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Transdermal contraception

The transdermal patch (Ortho Evra) consists of three layers. The middle layer contains norelgestromin and ethinyl estradiol. The inner layer is an adhesive and the outer is a protective cover. The patch contains 150 µg of norelgestromin and 20 µg of ethinyl estradiol. The first patch should be applied within the first 5 days of the menstrual cycle, and backup contraceptives should be used concomitantly for 7 days. A new patch should be applied every week for 3 weeks, followed by 1 patch-free week.

The patch exposes women to higher levels of estrogen than most oral hormonal contraceptive pills. The FDA has added new warnings that users could have twice the risk of blood clots than users oral hormonal contraceptives due to higher levels of estrogen exposure.

Application sites include the buttocks, abdomen, outer arms, and torso, except the breasts. The patch may be a good option for women who have difficulty adhering to other hormonal contraceptive regimens.

Physicians must balance the higher estrogen exposure against the chance of pregnancy. The patch completely detaches in 2% to 6% of cases. If it is replaced within 48 hours, no backup contraception is needed. If the patch-free interval exceeds 2 days, pregnancy should be ruled out, a new patch should be placed, and a backup contraceptive method should be used for 7 days. In case of skin irritation, the patch should be removed and a new patch applied to another site. Women weighing more than 198 pounds should not use the patch because its effectiveness is reduced. Ortho Evra offers no protection against STDs.

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Hormonal ring

The NuvaRing is a nonbiodegradable, flexible vaginal ring made of a polymer of ethylene vinyl acetate and magnesium stearate. The outer diameter of the ring is 54 mm, and the cross-sectional diameter is 4 mm. It releases 120 µg of etonogestrel and 15 µg of ethinyl estradiol daily. The ring is left in place for 3 weeks, followed by 1 ring-free week.

Vaginal discharge, vaginitis, and irritation can occur. Side effects are otherwise similar to those of oral combination pills.

The ring can be inserted at any time during the first 5 days of the menstrual cycle. A new ring should be inserted each month. The hormonal ring provides good cycle control.

If the ring is expelled during the first 3 weeks of use, it should be washed with lukewarm water and then replaced. If the ring-free interval is longer than 3 hours, a backup contraceptive method should be used concomitantly for 7 days. The ring should never be left in place for more than 4 weeks. If the ring is left in place, pregnancy should be ruled out before a new ring is inserted, and a backup method should be used for 7 days after inserting a new ring. It provides no protection against STDs.

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Intrauterine devices

There are currently two intrauterine devices (IUDs) on the market, the copper ParaGard T 380A and the levonorgestrel system, Mirena. Today's IUDs are safe and slightly more effective than oral contraceptives (see Table 1). The copper IUD is a -shaped device made of soft, flexible plastic with threads on the end that extend from the cervix and into the upper vagina. Copper IUDs induce a foreign-body reaction in the endometrium, leading to inflammation that prevents viable sperm from reaching the fallopian tubes.

The levonorgestrel-releasing IUD is a -shaped polyethylene device. The frame is 32 mm in both horizontal and vertical directions. The vertical stem contains a mixture of silicone and 52 mg of levonorgestrel surrounded by a Silastic capsule. The device releases 25 µg of levonorgestrel daily. It has an effective life of 5 years. It can be inserted within the first 7 days of onset of menstruation. This device causes changes in the lining of the uterus so that the fertilized egg cannot implant, and it thickens the cervical mucus to make sperm entry difficult.

Side effects include cramping during insertion, bleeding, pelvic inflammatory disease, and perforation of the uterus.

Spontaneity is maintained, and there are marked reductions in menstrual blood loss and dysmenorrhea. Copper IUDs last for 10 years; the Mirena system is effective for 5 years. Fertility returns rapidly after discontinuation of IUDs.

Expulsion of the copper IUD occurs in 5% of women during the first year. Expulsion rates for Mirena are a little higher than for copper IUDs. Each month, the woman should check the location of the threads of the copper IUD with her finger and she should notify the physician if she does not feel them. There is a mildly increased risk of ectopic pregnancy. Ovarian cysts are three times more common in users of this device. Twenty percent of women develop amenorrhea by the end of the first year of use. The risk of pelvic infection is higher during the first 20 days of Mirena insertion. There is also no protection against STDs.

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Barrier contraceptives

Prescription barrier methods include the diaphragm, cervical caps, and shields (Table 2). They cover the cervix and prevent sperm entry into the cervix. These devices are less effective than hormonal forms of contraception. The female condom and spermicides are nonprescription barrier methods. Female condoms are similar in efficacy to other barrier methods but have the benefit of some protection against STDs. Spermicides should be used in combination with other barrier methods.

Diaphragm

The diaphragm is a dome-shaped rubber disk with a flexible rim. The effectiveness depends on the proper fit as determined by the physician.

Cervical Cap

The cervical cap is smaller than a diaphragm. It fits securely in the vagina, covering the cervix, and must be fitted by a physician. Two types are available. The latex cervical cap (Prentif) has a firm, flexible rim. The silicone FemCap comes in three sizes, ranging from 22 mm to 30 mm. It is reusable for 2 years.

Cervical Shield

The cervical shield is a dome-shaped disk made of silicone. It has a one-way valve that creates suction by venting trapped air between the shield and cervix. It acts by preventing sperm entry. It also has a strap for easy removal. Lea's shield is the only one available. Spermicide should be applied to the device before insertion. Lea's shield should be replaced annually.

Side Effects, Advantages, and Precautions

Side effects of these barrier methods include vaginal irritation; allergic reactions to latex, silicone, or spermicide; urinary tract infections; and the rare risk of toxic shock syndrome if left in place too long. They are safe, effective, reusable, and have no effect on the menstrual cycle. These methods are less effective than hormonal contraception and provide no protection against STDs. Use of cervical shields can lead to falsely abnormal Papanicolaou (Pap) tests. Resizing should be done after abdominal or pelvic surgery, after any pregnancy longer than 14 weeks, and after any significant weight change. To protect against pregnancy, the devices should be left in place for a certain minimum of time after intercourse and then removed to decrease risk of infection.

Spermicides

Spermicides contain chemicals that kill or damage sperm. They come in the forms of creams, gels, films, suppositories, and tablets. Side effects include irritation, allergic reaction, and urinary tract infections. Spermicides are inexpensive and do not require a prescription. They offer no STD protection, and they are less effective and should supplement other barrier methods.

Contraceptive Sponge

The Today Sponge, a nonhormonal contraceptive spermicidal sponge is now back on the market for over-the-counter purchase. The effectiveness of the Today sponge when used appropriately and consistently is 89% to 91%. This is a nonhormonal contraceptive and lacks hormonal side effects. It requires no special fitting, becomes effective immediately after insertion, and protects against pregnancy for the next 24 hours without the need of additional spermicide. It mimics the feel of vaginal tissue and is therefore not detected by partners. The Today sponge should be kept in place for 6 hours after intercourse to ensure effective contraception. However, it should not be left in place for more than 30 hours after insertion.

Female Condoms

The Reality female condom consists of a lubricated polyurethane sheath with a flexible polyurethane ring on each end. One ring is inserted into the vagina much like a diaphragm, while the other remains outside, covering the labia. Side effects include irritation and allergic reactions. The female condom might offer some protection against STDs, but for highly effective protection, male latex condoms should be used instead. The male and female condoms should not be used at the same time because they will not both stay in place.

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Female sterilization

Hysteroscopic Sterilization

Hysteroscopic sterilization (Essure) is a new method of sterilization that uses a transcervical approach. The micro-insert consists of a stainless-steel inner coil, an elastic outer coil, and polyethylene fibers. The coil is inserted into the uterine end of the fallopian tube using a hysteroscopic technique. The outer coil expands to anchor the insert. The polyethylene fibers expand and cause inflammation and extensive fibrosis, resulting in permanent occlusion of the fallopian tubes by 12 weeks. Women should use a backup method for 12 weeks.

Side effects include pain after insertion and a small increased risk of ectopic pregnancy. Because this is a permanent method of contraception, women do not have to worry about pregnancy and the side effects of contraceptives.

Hysterosalpingography should be done at the end of 12 weeks to confirm tubal occlusion. Failure to correctly place the micro-inserts can lead to expulsion.

Tubal Ligation

Tubal ligation is a surgical procedure requiring anesthesia in which the fallopian tubes are cut or tied. The surgery takes about 30 minutes. The procedure does not affect sexual activity or the menstrual cycle. There is a risk of bleeding from the site, infection side effects from anesthesia, bowel or bladder injury, and injury to the skin. There is a slightly increased risk of ectopic pregnancy.

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Natural family planning

Sperm can live in the female reproductive tract for up to 7 days, whereas the egg lives for 1 day. Safe days occur 2 days after ovulation and continue until the next menses. This knowledge forms the basis for natural family planning.

In the ovulation method, the days just before and after ovulation are determined by checking cervical mucus. Mucus is stretchy and clear at the time of ovulation.

In the symptothermal method, daily temperature is recorded on a chart. Body temperature rises 2 days before ovulation. Consistency of cervical mucus is also monitored.

The rhythm method is based on calendar calculations of previous menstrual cycles. This method does not allow for normal changes in the menstrual cycle and is not as reliable as the ovulation or symptothermal method. This method is not recommended. Women who have no variation in the length of their menstrual cycle can use the rhythm method to know when they are ovulating (14 days before the start of menses).

The lactation amenorrhea method is a contraceptive method based on natural postpartum infertility, when a woman is amenorrheic and exclusively breastfeeding. The infant's suckling suppresses production of hormones. All three criteria—exclusive or near-exclusive breast-feeding, no menses since delivery, and less than 6 months postpartum—must be satisfied to effectively use this method.

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Emergency oral contraception

Plan B, or the levonorgestrel regimen, is the only emergency contraceptive pill regimen currently approved in the United States. It consists of two 0.75-mg levonorgestrel pills taken 12 hours apart. The first pill should be taken as soon as possible within 72 hours of unprotected intercourse.⁴ It has been approved for sale by pharmacists to women age 18 and older presenting photo identification. The Yuzpe regimen, marketed as Preven, is no longer available in the United States.

Emergency contraceptive pills are not teratogenic. Thus, a pregnancy test is not required before treatment. The only indication for emergency contraception is unprotected intercourse. Failure rate is 0.4% when treatment is initiated within 24 hours and 2.7% when treatment is initiated 48 to 72 hours after intercourse.

Plan B should not be used in cases of known or suspected pregnancy, hypersensitivity to components, or undiagnosed abnormal vaginal bleeding. Major side effects include nausea and vomiting.

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Conclusion

The range of available contraceptive options has increased markedly over the past 5 years. This progress is likely to continue as consumers seek safer, more-effective contraceptive methods. Improved counseling and knowledge should lead to more consistent and correct use of contraceptives and decreased numbers of unplanned pregnancies.

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Summary

• Unintended pregnancy is a major health problem; 50% of pregnancies are unplanned.
• The most effective and reversible contraceptive methods include the oral contraceptive, injectable contraceptive, implantable contraceptive, hormonal ring, and intrauterine devices.
• Barrier methods of contraception are less effective than hormonal forms of contraception.
• Natural family planning methods are not reliable and are not recommended.
• Levonorgestrel (brand name Plan B) is the only emergency contraceptive pill approved in the United States.

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Suggested Readings

• Burkman RT. Oral contraceptives: Current status. Clin Obstet Gynecol. 2001, 44: 62-72.
• Gallo MF, Grimes DA, Schulz KF: Cervical cap versus diaphragm for contraception. Cochrane Database Syst Rev 2002, I:CD003551.
• Kaunitz AM. Injectable long-acting contraceptives. Clin Obstet Gynecol. 2001, 44: 73-91.
• Rawlins S, Smith D. Innovative contraception: New options in hormonal contraception. Am J Nurse Practitioners. 2002, 6: 9-28.
• Thomas MA. Postcoital contraception. Clin Obstet Gynecol. 2001, 44: 101-105.