Progestins failure rate

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. 

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