Progestin-Only Contraceptives
Efficacy and mechanism of action
Two progestin-only contraceptives are commercially available. Norplant is composed of Silastic rods impregnated with the progestin levonorgestrel. The new Norplant system contains only two rods. A single-rod system will soon be available. The rods are inserted subdermally, generally in the upper arm. Diffusion of levonorgestrel through the wall of each capsule provides a continuous low dose of progestin for at least 5 years. The progestin modestly inhibits the hypothalamic-pituitary-ovarian axis to block ovulation; it also induces endometrial shedding, making implantation unlikely, and thickens cervical mucus,thereby retarding the entry of sperm and bacteria to the upper genital tract. The birth-control efficacy is greater than 99.9%.
Depot medroxyprogesterone acetate (DMPA) is an aqueous suspension of 150 mg designed to be given intramuscularly every 3 months. The birth-control efficacy is greater than 99%.
Side effects
Subdermal and injectable progestins have side effects [see Table 5]. The principal side effect is breakthrough bleeding caused by the development of fragile endometrial vessels and local derangement of hemostatic mechanisms as a result of excess progestin exposure relative to estrogen exposure.5 The breakthrough bleeding may respond to the administration of an estrogen such as transdermal estradiol. Progestin implants and injections are relatively contraindicated in women with past or active depression or other psychiatric disorders [see Table 6]. There is some suggestion that progestin-only contraceptives are more mood destabilizing than COCs. The long-term effect on bone accretion depends on the extent of ovarian suppression and its attendant decline in estradiol secretion and on the age of the patient. Younger patients who have not attained peak bone mass may be more adversely affected. Lev-onorgestrel may be more bone sparing than DMPA. Progestin-only contraceptives have been found to increase the risk of diabetes mellitus in Latin-American women who have had gestational diabetes (see above).15 This may be partly caused by the lack of estrogen, which is an insulin sensitizer. The long-term cardiovascular risks are largely unknown, but in some experimental settings, synthetic progestins provoke vasoconstric-tion, an effect not seen with progesterone. A recent epidemio-logic analysis from the World Health Organization (WHO) found no excess risk of cardiovascular disease with either combined or progestin-only methods other than an increased risk of stroke in hypertensive women who were given the pro-gestin-only contraceptives.
Another common side effect of progestin-only contraceptives is delay in return of menses. DMPA is given at 90-day intervals, but patients who discontinue this method may not experience immediate return of menses because of variability in the metabolism of the depot form and variable sensitivity of the hypothalamic GnRH pulse generator to low levels of progestin.
Intrauterine Devices
IUDs interfere with sperm migration, fertilization, ovum transport, and implantation, presumably by causing a sterile salpingitis, endometritis, or both. The birth-control efficacy is greater than 97%.
One of the principal benefits of IUDs is that they provide a nonhormonal method of birth control. They are ideal for women who have completed childbearing and who desire a low-maintenance, reversible method of contraception. IUDs are also relatively economical.
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Table 5 Potential Side Effects of Injectable and Implantable Progestin Contraceptives |
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Breakthrough bleeding Headaches |
Mastodynia Acne |
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Mood changes |
Bone loss |
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Weight gain |
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Table 6 Contraindications to Injectable and Implantable Progestin Contraceptives |
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Active liver disease |
Active thromboembolic disease |
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Diabetes mellitus |
Active cardiovascular disease |
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Unexplained vaginal bleeding |
Depression |
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Breast cancer |
Other psychiatric disorders |
Two IUDs are currently available: the Copper T 380A, which lasts 10 years, and the 5-year, levonorgestrel-releasing Mirena. With the copper IUD, both the inert plastic device and the copper contribute to the spermicidal effect and prevention of implantation. With the progestin-containing IUD, part of the efficacy is attributed to the effects of the progestin on the en-dometrium that retard implantation.24
The main side effect associated with IUD use is pelvic inflammatory disease (PID). Most of the increased risk of PID occurs in the first 3 weeks after insertion. Women with more than one sexual partner who are at risk for contracting gonorrhea and chlamydial infection also are at increased risk for PID. Patient selection, rigorous aseptic insertion technique, and screening for STDs may minimize this risk. Routine antibiotic prophylaxis during insertion may not be necessary.25 Uterine perforation is a rare insertion risk. Dysmenorrhea and menorrhagia have been reported with the copper IUD, whereas decreased menstrual flow, dysmenorrhea, and increased risk of ectopic pregnancy have been reported with the progesterone-releasing IUD.
The primary contraindication to IUD use is a history of PID. Nulligravidity is a relative contraindication. Sexual monogamy should be emphasized as a means of minimizing the risk of STDs and PID.
Barrier Methods
Male and female barrier contraceptives are available. When used correctly, the male condom protects against pregnancy and STDs. The theoretical efficacy of barrier methods for birth control is 98%, but the actual efficacy is about 88%. The efficacy gap results from inconsistent use and condom breakage. The female condom is more difficult to use and has not gained popularity. The diaphragm and cervical cap do not protect against STDs as effectively as condoms. When they are used with spermicides, the birth-control efficacy of diaphragms and cervical caps is theoretically 94%; in practice, however, the efficacy is about 82%. Both cervical caps and diaphragms require fitting and a prescription. They also require user training and diligence. Instructions on their use are provided in the products’ package inserts. Spermicides may independently decrease the risk of STDs. When used alone, spermicides have a birth-control efficacy of about 79%.3 Spermicides that also have antimicrobial activity are in development.
Allergic reactions to latex and hypersensitivity to spermicides occur. Diaphragm use may increase the risk of urinary tract infections because the rim presses against the symphysis pubis and urethra, which may cause incomplete emptying of the bladder.
The main contraindication to barrier methods is lack of user motivation and hypersensitivity to spermicides or allergy to latex. The primary benefits of condoms are that they are available without prescription, inexpensive, relatively easy to use, nonhormonal, and protective against STDs. Other barrier methods are only slightly more difficult to use but require fitting and a prescription, so the need for birth control must be anticipated.
Periodic Abstinence
Periodic abstinence, or natural family planning, depends on recognition of the periovulatory window and avoidance of sexual intercourse during that window. As such, it requires that a woman have highly regular menstrual cycles and that both partners be motivated to avoid intercourse when the woman is fertile. There are several methods of detecting the fertile window, including avoiding intercourse on days 9 to 14 of a 28-day cycle, monitoring cervical mucus and body temperature, and monitoring salivary estradiol levels.
Mastering the concepts of menstrual-cycle physiology can be empowering, and couples can use this information to plan a pregnancy as well as to avoid it. There are no known contraindications. There are no religious prohibitions against periodic abstinence, so it is theoretically available to all women who have predictable cycles.
Periodic abstinence can be frustrating, however, and it is less reliable than other forms of contraception, with an estimated efficacy of 80%. Several factors can interfere with fertility awareness. Even women who usually have very regular cycles may occasionally have a cycle that deviates from normal. Vaginitis may obscure the recognition of midcycle mucus. Fever may mimic the progesterone-induced rise in body temperature that normally indicates the onset of the luteal phase, thereby falsely signaling that the fertile period has passed.
Sterilization
Sterilization procedures generally entail occlusion or ligation of the fallopian tubes in women or the vas deferens in men. The birth-control efficacy of sterilization procedures is greater than 99%; they are meant to be permanent. Reversal procedures are available, but the reversibility of tubal ligation or vasectomy is not guaranteed. Sterilization procedures may fail if the fallopian tube is not properly identified or if it recannulates. Vasectomy failures primarily result from not waiting a sufficient length of time after the procedure before having unprotected sexual intercourse. In women, sterilization procedures can be done post par-tum, but interval procedures are safer and more effective. Interval procedures employ laparoscopy, with or without general anesthesia. The fallopian tubes are either fulgurated or banded.
Patients may experience feelings of regret after a tubal liga-tion or vasectomy. Appropriate counseling can minimize this emotional side effect. There is no concrete evidence that vasec-tomy causes heart disease or prostate cancer. A recent review of tubal ligation found no evidence of increased rates of premenstrual distress, menorrhagia, dysmenorrhea, or menstrual irregularities in women 30 years of age or older who had undergone interval tubal ligation.26
The main contraindication to sterilization is ambivalence. In addition, women who undergo laparoscopic procedures must be suitable surgical candidates. The main benefit of sterilization is its permanence. Because sterilization is a one-time procedure with high efficacy, it is highly cost-effective in appropriately selected candidates. Tubal ligation may decrease the risk of PID and ovarian cancer.
Emergency Contraception
Postcoital contraception aims to desynchronize endometrial development and prevent implantation. Various methods have been proposed.27 They include high doses of COCs taken within 72 hours after intercourse; levonorgestrel taken within 72 hours after intercourse; high doses of estrogen; danazol; mifepristone, as a single 600 mg dose; and insertion of a copper IUD up to 5 days after ovulation. The contraceptive efficacy of mifepristone or IUDs is at least 99%. One study compared a treatment consisting of 100 |ig of estrogen plus 0.5 mg of levonorgestrel taken twice, 12 hours apart, with a treatment consisting of lev-onorgestrel, 0.75 mg, taken twice, 12 hours apart.28 Both treatments were taken within 72 hours after intercourse. Lev-onorgestrel alone had an efficacy of 85% and was associated with fewer side effects than the combined therapy, which had an efficacy of 57%. The efficacy of levonorgestrel taken within 24 hours after intercourse was greater than 99%. This would appear to be the treatment of choice because it is inexpensive, widely available, well tolerated, and highly effective. A recent Scottish study also suggested that women given a single emergency contraceptive kit used it correctly without experiencing significant side effects, and they had a lower unintended pregnancy rate.29 Given the safety and efficacy of emergency contraception, many physicians strongly advocate that it be made available over the counter.30 Patient information on emergency contraception is available on the Internet at http://ec.princeton.edu.
Choosing a Contraceptive Method
There is no perfect contraceptive; all may fail, and all have drawbacks and side effects. Age, motivation, marital status, partner attitude, perceived risk of pregnancy, frequency of intercourse, medical conditions, costs, cultural considerations, and religious beliefs affect the choice of contraceptive methods. The patient’s or couple’s medical history and preferences must guide the selection of a contraceptive [see Table 7]. Patients should be encouraged to revise their choice on the basis of side effects and changing circumstances.
Patients should be advised to inform the physician of new symptoms before discontinuing a contraceptive method. The physician must remain sensitive to the patient’s concerns. Even if a symptom sounds trivial from a medical perspective, it may alarm the patient and cause her to discontinue the method.
The role of condoms and other contraceptives in the reduction of STD transmission must be emphasized so that patients can choose properly from among the available options. Emergency contraception should be discussed and offered to those not seeking long-term contraception.
Reversible method desired
The first decision point in the choice of a reversible contraceptive method hinges on whether the patient has more than one sexual partner or is in a long-term monogamous relationship. If the patient has more than one sexual partner, condoms with or without hormonal contraception should be recommended. User reluctance and lack of familiarity are the main limitations to condom use. Condoms are ideal for unplanned intercourse.
Table 7 Contraceptive Characteristics Affecting Choice29
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Characteristic |
Method |
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High efficacy |
Combined oral contraceptives |
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Intrauterine devices |
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Depot medroxyprogesterone acetate |
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Subdermal progestin implants |
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Limited or no systemic side effects |
Barriers |
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Spermicides |
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Periodic abstinence |
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Minimal effort |
Intrauterine devices |
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Subdermal progestin implants |
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Depot medroxyprogesterone acetate |
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Low cost |
Male condom |
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Spermicides |
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Combined oral contraceptives |
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Nonprescription |
Male condom |
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Spermicides |
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Periodic abstinence |
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No religious prohibitions |
Periodic abstinence |
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Protection against sexually transmitted diseases Cervical gonorrhea and chlamydial infection |
Barriers |
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Salpingitis |
Barriers, hormone contraceptives |
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HIV infection |
Male and female latex condoms |
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Other health benefits |
Hormone contraceptives |
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Minimal risk to future fertility |
Hormone contraceptives |
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Barriers |
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Periodic abstinence |
For healthy women, the ancillary health benefits of combined estrogen-progestin contraceptives should be emphasized. These include a reduced risk of ovarian and endometrial cancer and preservation or accretion of bone mass. The option of using combined hormonal contraceptives to regulate menstrual timing should be discussed as a means of aiding compliance.
COCs, particularly the generic brands, are relatively inexpensive—in the range of $10 to $20 a month. COCs work best if taken daily, and some women find it difficult to remember to do so; they may prefer a vaginal ring, transdermal patch, or in-jectable contraceptive. Women who do not take the pills reliably will have increased rates of pregnancy and side effects, such as breakthrough bleeding. They should be counseled to use a barrier method or spermicide if they miss two consecutive pills or if they start the next package of pills after a hiatus of 8 or more days. In healthy nonsmokers without predisposing medical conditions, the pill is a safe and highly efficacious method of contraception that can be used in women up to 50 years of age. In women who are approaching menopause, COC use not only provides effective contraception but also can regularize menstrual cycles, relieve vasomotor symptoms, and stabilize bone mass.31
Women with epilepsy may need to have their antiseizure medications adjusted when they start oral contraceptive therapy. Not all the newer antiseizure drugs interact with oral contraceptives, however,32 so patients need to be evaluated on a case-by-case basis. Consultation with a pharmacist may be useful.
Follow-up is important in women who choose hormonal contraceptives. Blood pressure should be measured around 3 months after the start of COCs and annually thereafter. If hypertension results, it is prudent to discontinue COCs. Women using hormonal contraception who develop a severe, unremitting headache should be evaluated for possible stroke and cerebral thrombosis.
With prolonged use of COCs—even on a cyclic regimen— some women develop endometrial atrophy and amenorrhea. Once pregnancy has been excluded, it is prudent to recommend a long-cycle or a continuous regimen or one with a shortened placebo window.
It is prudent for women who develop serious mood disturbances to discontinue COCs. Women with active or past PMS and depression, including postpartum depression, should be advised about the potential for negative mood effects associated with COCs.
Switching to a lower-dosage regimen may reduce nuisance side effects. Physically smaller women or women who metabolize synthetic sex steroids slowly (such as women of Asian descent) should start with a 20 |ig pill. Although most women do well on 20 |ig pills, there may be a slight increase in breakthrough bleeding with some formulations. The benefit is fewer estrogen-dependent side effects, such as breast tenderness or nausea. Women with a history of headaches may do better on the lowest dose given in a continuous or nearly continuous (Mircette) regimen.
If a patient has a low risk of depression, PMS, and osteoporosis, Norplant or DMPA may be an appropriate method of contraception. The patient must desire extended protection and be willing to undergo the insertion procedure or an injection. Subdermal implants and DMPA are relatively expensive.
The DMPA cannot be removed if a patient experiences adverse effects, and continuance rates are low with DMPA. Insertion of subdermal implants requires training and skill. If adverse effects occur with subdermal implants, a surgical procedure is required for their removal. Removal is often more difficult than in-traduction because of scarring around the capsules. In appropriate patients, however, subdermal implants provide a long-term, low-maintenance birth-control method.
IUDs, barrier methods, or periodic abstinence may be considered if the patient is not a candidate for hormone contraception and is in a long-term monogamous relationship.
Prospective users of IUDs must be made aware of the attendant risks and benefits. To make an informed decision, users need to understand the risks and potential consequences of PID.
Diaphragms and cervical caps are ideal for highly motivated users who desire a nonhormonal method of birth control. Spermicides increase the efficacy of all barrier methods of contraception but also increase cost and bother. Use of barrier methods is increased by public health education and by suggestion that the barrier method be incorporated into foreplay.
Women who report vaginal pruritus, irritation, inflammation, pain, or discharge associated with the use of a barrier method may have a latex allergy or hypersensitivity to spermi-cide. Latex allergies are particularly common in health care workers, many of whom are women. Formal allergy testing can be done to detect latex allergy, but current tests are not highly reliable. Latex allergy can provoke life-threatening ana-phylaxis. Although most spermicides contain nonoxynol-9 as the active contraceptive ingredient, the other constituents may vary. Therefore, it may be possible to minimize irritation by switching to a different preparation. Men may also report allergies to latex or hypersensitivity to spermicides. Latex is preferred for condoms and barrier methods because it is impermeable to HIV.
Nonreversible method desired
All potential reversible and permanent options must be reviewed before a sterilization procedure is chosen. In general, if a couple seeks sterilization, a vasectomy is recommended because it is safer and less expensive than a laparoscopic tubal li-gation. Postpartum tubal ligation is the most risky, least effective, and most likely to cause regret.
Laparoscopic tubal ligation is expensive and must be performed by a skilled surgeon in an appropriate setting, so availability may be limited by cost or access to an appropriate physician. Many states require mandatory waiting periods. Some require spousal consent. Counseling is the cornerstone of success.
