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Ninety percent of women who are at risk for pregnancy use some form of birth control. Over a 5-year period, the cost to the medical system of providing reproductive health care services to sexually active patients who do not use contraception was estimated in 1995 to total $14,000 per woman.
CONTRACEPTIVE EFFICACY
As with many other preventive medical interventions, efficacy of contraceptive methods cannot be directly measured; only failures can be quantified. Increased efficacy is, therefore, reflected in lower failure rates and depends on two factors: 1) the intrinsic effectiveness of the method and 2) its correct use.
CONTRACEPTIVE OPTIONS
In counseling a patient about her contraceptive options, her medical and social situation should be evaluated to ensure that no contraindication to a specific method exists. A separate evaluation should be made of the patient's risk for acquiring or transmitting STIs, but it need not change her choice of contraception. The patient's contraceptive needs should be met by the most effective birth-control method for which she is a candidate; her needs for STI protection should be carefully addressed by counseling about safer sex practices and, for those unable to change their situations, by provision of condoms. Nearly one of every four women in the United States relies on permanent sterilization of herself or her partner. It is the most common and most effective form of contraception .
EMERGENCY CONTRACEPTION
Women exposed to sperm by unprotected intercourse, condom breakage, or other contraceptive mishaps are candidates for emergency contraception with oral contraceptives. After reviewing the three decades of clinical experience with emergency contraception in this country, the FDA Advisory Board has now approved emergency contraception with oral contraceptives. The Yuzpe regimen calls for two tablets, each containing ethinyl estradiol 0.05 mg and DL-norgestrel 0.5 mg, to be taken within 72 hours.
ORAL CONTRACEPTIVES
Combination oral contraceptives contain both a synthetic estrogen and progestin. Ethinyl estradiol is the estrogen used in all of the sub-50-ug formulations and also in many of the 50-ug pills. Its 3-methyl ester, mestranol, is used in a few of the 50-ug pills; mestranol must be hepatically converted to ethinyl estradiol to become biologically active.
All progestins in oral contraceptives are 19-nortestosterone androgen derivatives. There are seven different progestins available in the United States; they vary in progestational and residual androgenic activities. The first-generation progestins include norethindrone as well as norethynodrel, norethindrone acetate, ethynodiol.
Formulations
Combination oral contraceptives containing both a synthetic estrogen and progestin are taken daily, typically in a pattern of 3 weeks of active pills followed by a 1-week steroid-free period. Combination oral contraceptives are available in monophasic and multiphasic formulations. With the monophasic formulation, each active pill contains the same amount of sex steroid; with the multiphasic formulation.
SPECIAL APPLICATIONS
Oral contraceptives are an excellent contraceptive choice for adolescents at risk for pregnancy. Early use does not interfere with maturation of the hypothalamic-pituitary-ovarian axis and will not induce premature closure of the epiphyseal plates. Pills provide many important benefits, including decreased acne, menstrual regulation, and decreased dysmenorrhea. Early use facilitates long-term use, which can lead to significant health benefits in reduction of endometrial and ovarian carcinoma and reduced risks for ectopic pregnancy, PID, menorrhagia, anemia, benign breast disease, leiomyoma, and perhaps even coronary artery disease and rheumatoid arthritis. Oral contraceptives also arrest further bone loss by providing an estrogen source for young women who are amenorrheic due to eating disorders.
INTRAUTERINE CONTRACEPTIVE DEVICES
Types
Two different types of IUDs are available in the United States. The ParaGard T380A Copper IUD is a T-shaped plastic IUD with copper wire wrapped around the stem and a solid copper sleeve on each of the arms. Approved for 10 years of use, its first-year typical failure rate is 0.7% and its cumulative 10-year failure rate is 2.1%. These rates compare favorably to the failure rate of sterilization, particularly in younger women. More than 75% of women continue IUD use after the first year, and 80-90% continue each subsequent year. The Progestasert IUD is also a T-shaped device with a stem filled with progesterone, which is slowly released over its 12-month approved life. The arms stabilize the unit within the uterine cavity. Its failure rate is about 2.5% per year.
The contraceptive effects of each type of IUD are completely reversible. Follow-up studies of women seeking pregnancy after IUD use show no difference in fertility rates between former IUD users and former barrier.
Selection of Candidates
The IUD is a safe, convenient, and effective contraceptive intended for use by women at low risk for acquiring STIs. Specifically, the ParaGard IUD is well suited for women seeking intermediate to long-term contraception who have been pregnant, are in stable and mutually monogamous relationships, and have not had PID. Because the Progestasert IUD is slightly less effective and requires annual replacement, it is generally reserved for women who otherwise qualify for an IUD but might not tolerate some of the features or effects of the ParaGard IUD.
Absolute contraindications for IUD use include pregnancy, multiple sexual partners, active cervical infection, recent endometriosis, a history of PID, the presence of another IUD, undiagnosed abnormal genital bleeding,
Mechanisms of Action
Modem IUDs function as contraceptives, not abortifacients. The Progestasert IUD is a local delivery system of progesterone, which thickens impenetrable cervical mucus to block sperm penetration. In addition, the atrophic endometrium discourages implantation. The mechanisms of action for the ParaGard IUD have been more difficult to elucidate, but numerous studies demonstrate that copper IUDs.
Effects and Complications
Both types of IUDs affect menstruation. The ParaGard IUD typically increases menstrual blood loss about 35%, but this loss can be reduced by nonsteroidal antiinflammatory drags (NSAIDs) administered at the
LONG-ACTING PROGESTIN METHODS
Both the Norplant-6 system and depot medroxyprogesterone acetate (DMPA) injections are intermediate- to long-term progestin-only contraceptive methods that are highly effective, convenient, and estrogen free. There are few contraindications to their use; even many women with serious medical problems are candidates for these methods. Women who are breast-feeding are also excellent candidates for long-acting progestin
Contraceptive Implants
The Norplant system consists of six silicone rubber capsules, each filled with 36 mg of levonorgestrel. The capsules are placed in a superficial plane beneath the skin of the medial aspect of a woman's upper arm. Levonorgestrel is slowly released from the capsules, providing rapidly reversible contraception for up to 5 years. The insertion procedure is relatively straightforward but requires training to ensure good cosmetic
Depot Medroxyprogesterone Acetate
Depot medroxyprogesterone acetate is an aqueous suspension of microcrystals of progestin given by intramuscular injection every 11-13 weeks. The approved contraceptive formulation has a concentration of
BARRIER METHODS
Barrier methods are coitally related and require timely and consistent user participation. As such, they have
Male Condoms
Male condoms have typical failure rates of 10-12% but range as high as 20% with teenagers. Perfect-use
Female Barrier Methods
The diaphragm, cervical cap, female condom, and spermicidal agents are the currently available female barrier methods. For nulliparous women, the diaphragm and cervical cap have similar typical failure rates