Contraception failure rate

Women weighing more than 160 lb (72.7 kg) may have higher contraceptive failure rates with low-dose OCs and may benefit from pills containing 35 to 50 meg of EE. 

Moreno, L., and N. Goldman. 1991. Contraceptive failure rates in developing countries Evidence from the demographic and health surveys. Int Fam Plan Perspect 17 44. 

Jones, E.F., and J.D. Forrest. 1992. Contraceptive failure rates based on the 1988 NSFG. Fam Plan Perspect 24 12. 

Helms SE, Bredle DL, Zajic J, Jarjoura D, Brodell RT, Krishnarao I. Oral contraceptive failure rates and oral antibiotics, JAm Acad Dermatol (1997) 36,705-10. 

Progestin-only contraceptives (Fig. 4) contain low-doses of progestins (e.g. 350 pg norethindrone or 75 pg norgestrel) that have to be administered daily without interruption. The lowest expected failure rate during the first year of use is 0.5%, while the typical failure rate amounts to 3%. Subdermal implants of norgestrel (216 mg) for sustained release provides for long-term (for up to 5 years) contraceptive effects characterized by failure rates of only 0.05%. Reliable contraception for 3 months can be achieved by an intramuscular injection of a crystalline suspension of 150 mg medroxyprogesterone acetate (Fig. 3) (failure rate 0.3%). 

Pregnancy failure rates with the long-acting progestin contraception are comparable to that of female sterilization. 

Like all women, older women who take oral contraceptives should take an oral contraceptive that contains the least amount of estrogen and progestin that is compatible with a low failure rate and individual patient needs. 

Oral contraceptive medications are among the most prescribed and effective drugs. The failure rates associated with various methods of contraception are cited in the following table. 

Choosing a contraceptive method most suited to the patient s needs will reduce the chance of unintended pregnancy significantly. Typical failure rates for some of the commonly used methods of reversible contraception are listed in Table 77-1. A medical and sexual history and a thorough physical examination are essential when evaluating the various methods available. Understanding the risks and precautions associated with the methods available is essential for both the patient and the prescriber (see Tables 77-1 and 77-3). 

Antiseizure therapy has importance implications for women s health. The efficacy of oral contraceptives is reduced by concomitant use of antiseizure drugs (failure rate of 3.1/100 years versus 0.7/100 years in nonepileptic controls) this may relate to the increased rate of oral contraceptive metabolism caused by antiseizure drugs that induce hepatic enzymes (Table 19-2) particular caution is needed with antiseizure drugs that induce CYP3A4. 

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