According to the 2006–2010 National Survey of Family Growth (NSFG), approximately one-half of all pregnancies in the United States were unintended. These rates have remained relatively unchanged since 1995. However, changes in contraceptive method use among married, non-Hispanic white women have contributed to a significant decline in the proportion of unintended births among this group. Sixty-two percent of women of reproductive age are currently using contraception. Of women using a contraceptive method, the most common methods used are the oral contraceptive pills (28%) and female sterilizations (27%). Use of intrauterine devices has increased since 1995, from 0.8% to 5.6%, whereas fewer women report that their partners are using condoms as their current most effective means of contraception. Addressing family planning and contraception is an important issue for providers of care to reproductive-age women. Because of the wide range of contraceptive options available, it is important that health care providers maintain currency with the recent advances concerning counseling, efficacy, safety, and side effects.
K Current Contraceptive Use in the Unites States, 2006-2010, and Changes in Patterns of Use Since 1995. National Health Statistics Reports no 60. Hyattsville, MD: National Center for Health Statistics; 2012.
COMBINED ORAL CONTRACEPTIVES
According to the 2006–2010 NSFG, the combined oral contraceptive pill is the leading contraceptive method among women, with 28% of women between the ages of 15–44 choosing the pill. The availability of lower-dose combination oral contraceptives (COCs) (<50 μg ethinyl estradiol) has provided many women a highly effective, safe, and tolerable method of contraception.
Combined oral contraceptives suppress ovulation by diminishing the frequency of gonodotropin-releasing hormone pulses and halting the luteinizing hormone surge. They also alter the consistency of cervical mucus, affect the endometrial lining, and alter tubal transport. Most of the antiovulatory effects of COCs derive from the action of the progestin component. The estrogen doses are not sufficient to produce a consistent antiovulatory effect. The estrogenic component of COCs potentiates the action of the progestin and stabilizes the endometrium so that breakthrough bleeding is minimized. When administered correctly and consistently, they are >99% effective at preventing pregnancy. However, failure rates are as high as 8–10% during the first year of typical use. Noncompliance is the primary reason cited for the difference between these rates, frequently secondary to side effects such as abnormal bleeding and nausea.
The estrogenic agent most commonly used in COCs is ethinyl estradiol (EE), in doses ranging from 20 to 35 μg. Mestranol, which is used infrequently, is less potent than ethinyl estradiol such that a 50-μg dose of mestranol is equivalent to 30–35 μg of ethinyl estradiol. It appears that decreasing the dose of estrogen to 20 μg reduces the frequency of estrogen-related side effects, but increases the rate of breakthrough bleeding. In addition, there may be less margin for error with low-dose preparations such that missing pills may be more likely ...