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For further information, see CMDT Part 18-10: Contraception

Key Features

General Considerations

  • Unintended pregnancies are a worldwide problem but disproportionately impact developing countries

  • Studies estimate that 40% of the 213 million pregnancies that occurred in 2012 were unintended

  • Globally, 50% ended in abortion, 13% ended in miscarriage, and 38% resulted in an unplanned birth

  • Primary care providers need to educate their patients about the benefits of contraception and to provide them options that are appropriate and desirable



Oral contraceptives

  • Combination pills

    • Have a theoretical failure rate of only 0.3% if taken absolutely on schedule but a typical use failure rate of 8%

    • Primary mode of action is suppression of ovulation

    • Pills can be started on the first day of the menstrual cycle, on the first Sunday after the onset of the cycle, or on any day of the cycle

      • If started on any day other than the first day of the cycle, a backup contraceptive method should be used

      • The combination pill is taken daily for 21 days, followed by 7 days of placebos or no medication, and this schedule is continued for each cycle

    • Pills are typically packaged in 21- or 28-day cyclic regimens but may be taken continuously to allow the user to decide if and when she has a withdrawal bleed

    • Studies have not shown any significant risk from long-term amenorrhea for patients taking this continuous oral contraceptive regimen


  • There are many noncontraceptive advantages to oral contraceptives

    • Menstrual flow is lighter

    • Decreased risk of ovarian and endometrial cancer

    • Improvement in acne

    • Dysmenorrhea, pain with ovulation and postovulatory aching are relieved for most women

    • Functional ovarian cysts generally disappear with oral contraceptive use, and new cysts do not occur

    • There is also a beneficial effect on bone mass

  • Selection

    • Any of the "low-dose" combination oral contraceptives (containing 35 mcg or less of ethinyl estradiol or 3 mg of estradiol valerate) are suitable for most women

    • There is some variation in potency of the various progestins in the low-dose pills, but this variation results in essentially no clinically significant differences for most women

    • Women who have acne or hirsutism may benefit from use of one of the pills containing the third-generation progestins, desogestrel or norgestimate, since they are the least androgenic

    • The low-dose oral contraceptives commonly used in the United States are listed in Table 18–2

  • Drug interactions

    • Drugs that interact with oral contraceptives potentially decreasing their efficacy include

      • Phenytoin

      • Phenobarbital (and other barbiturates)

      • Primidone

      • Topiramate

      • Carbamazepine

      • Rifampin

      • St. John's wort

    • Women taking these drugs should use another means of contraception for maximum protection

    • Antiretroviral medications, specifically ritonavir-boosted protease inhibitors, may significantly decrease the efficacy of combined oral contraceptives, and the concomitant use of oral contraceptives may increase the toxicity of these antiretroviral agents


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