A year ago, the US Food and Drug Administration (FDA) granted over-the-counter (OTC) status for Plan B, the levonorgestrel-only emergency contraceptive. In the past few years, we have accumulated data on the general impact of improved access to emergency contraception (EC), as well as evidence of its overall efficacy. We also have another year of experience with the levonorgestrel-releasing intrauterine system (Mirena) and its multiple benefits beyond contraception, and with extended hormonal contraceptive regimens. This article highlights what we know about these three forms of contraception.
Greater access to Plan B leads to increased—and faster—use
Now that Plan B is available OTC to both men and women 18 years and older,1 several questions are in order:
- What are the effects of this change?
- Does OTC access or provision of the drug in advance reduce condom or oral contraceptive use?
- Does it increase the number of sexual partners or rate of sexually transmitted disease (STD)?
- Does it reduce unintended pregnancy?
Several randomized trials have found that advance provision of EC not only increases its utilization, but causes it to be used sooner.2-7 Most of the trials conducted so far have compared advance provision of EC with counseling about EC or a prescription for it. Only one trial has included a pharmacy-access arm, and it was conducted before FDA approval of OTC status.3 It found that pharmacy access did not increase use of EC, compared with standard access (ie, returning to the clinic when EC was needed). It is too early to tell what effect OTC availability will have on the usage rate, but data so far support the practice of giving the patient a supply of EC rather than just a prescription.
Increased access to EC does not affect regular contraceptive behavior
Multiple studies have shown that advance provision of EC has no significant effect on the use of regular contraception. Studies have examined the impact of EC on both baseline oral contraceptive usage and condom usage and found no significant change in either among women who used EC during the study.3-6
… nor does it cause promiscuity or increase the rate of STD
Multiple studies have demonstrated that advance provision of EC does not increase the number of sexual partners or rate of STD.3-6 The largest of these studies compared both pharmacy access without a prescription and advance provision of EC to standard access. That study included 2,117 sexually active young women and found no difference in the rate of STD or number of sex partners among the three study groups.3 Smaller studies comparing advance pro-vision of EC with standard access also found no significant difference in these variables.8,9
No evidence of fewer unintended pregnancies—yet
We know that progestin-only EC can reduce unintended pregnancy by almost 90%.10 However, studies have not yet demonstrated such a decrease in the general population. One reason may be that the two studies that considered unintended pregnancy as a primary outcome3,9 were too small to detect a difference in pregnancy rates, or it may be that EC was underutilized by women in the studies.
Prescribing information for levonorgestrel emergency contraception (EC) recommends ingestion of the first 0.75-mg tablet within 72 hours (3 days) of a single act of unprotected intercourse, with the second tablet taken 12 hours after the first.11 However, data show that levonorgestrel EC can prevent pregnancy up to 5 days after intercourse. In a World Health Organization multicenter randomized trial of various EC regimens, levonorgestrel EC prevented 79% to 84% of expected pregnancies when taken within 1 to 3 days, and 60% to 63% when taken 4 to 5 days after intercourse.12 Randomized trials have also found that taking both 0.75-mg levonorgestrel pills simultaneously prevents pregnancy as effectively as taking them 12 hours apart.
Levonorgestrel EC prevents or delays ovulation by inhibiting the luteinizing hormone surge during the follicular phase.13 Secondary mechanisms of contraceptive action include thickening of the cervical mucus; decreased pH level, which immobilizes sperm; and decreased recovery of sperm from the uterus.14