Emergency Contraception: Hopes and Realities
Worldwide, approximately 40 percent of the pregnancies that occur each year are unintended (Dailard 1999). For individual women and their partners, families, and communities the consequences of unintended pregnancy are significant. On the macro level, the public health, health systems, and economic impacts of unintended pregnancy are also considerable. For decades, researchers, advocates, scientists, and policymakers have worked to address unmet family planning needs and support initiatives to increase women’s reproductive autonomy. Emergency contraception (EC), a category of medications and devices that are used post-coitally, represents a last chance for individual women to prevent pregnancy. EC also has the potential to reduce the incidence of unintended pregnancy and the consequent need for abortion (Trussell et al. 1992). But this potential has not been realized, and it is unlikely that EC will have a major population level impact.
To understand the national and global debates about the introduction of EC, the discourse surrounding its promised and actual impact, and the claims made by proponents and opponents of expanding access, it is important to understand the science of EC. This chapter provides a detailed overview of the range of emergency contraceptives available worldwide and aims to provide a framework by which the debates surrounding EC at the individual country level can be situated (Glasier 1997; Hatcher et al. 1995; Stewart, Trussell, and Van Look 2004). Through an extensive review of the body of scholarly literature on EC, this chapter summarizes the scientific evidence on effectiveness, mechanism of action (i.e., how it works to prevent pregnancy), safety, side effects, and drug interactions. Finally, this chapter explores the debates over the public health impact of EC and engages the social science research on topics ranging from cost effectiveness to the impact on pregnancy and abortion rates.
Emergency Contraceptive Pills
Emergency contraceptive pills (ECPs) are the most widely known form of post-coital contraception. By the middle of 2010, there were three types of ECPs in existence: combined ECPs, so called because they contain a combination of estrogen and progestin; progestin-only ECPs, the most commonly available EC product; and ECPs containing an antiprogestin. These three types of ECPs comprise different medications, require different dosing schedules, and have different side-effect profiles. However, all three pill-based regimens of EC can be initiated immediately after intercourse and can reduce the risk of pregnancy if taken up to 120 hours after sex has occurred.
Combined ECPs contain estrogen and progestin. These are the same hormones found in many daily oral contraceptive pills (OCPs), but when used post-coitally for pregnancy prevention the hormones must be given in a higher dose. The estrogen ethinyl estradiol and the progestin levonorgestrel or norgestrel are the hormones that have been most extensively studied, and post-coital use of this combination of active ingredients is often called the Yuzpe method. The regimen is one dose followed by a second dose 12 hours later. When dedicated ECPs (i.e., pills that are packaged and marketed specifically for use as EC) are not available, certain daily OCPs can be used post-coitally in specified combinations to reduce the risk of pregnancy. Each dose may consist of anywhere from one to six pills, depending on the brand and the amount of hormones contained in each pill. Newer research has demonstrated the safety and efficacy of an alternative combined regimen containing ethinyl estradiol and the progestin norethindrone (Ellertson et al. 2003b); this result suggests that OCPs containing progestins other than levonorgestrel may also be used for post-coital pregnancy prevention.
Progestin-only ECPs containing no estrogen have now largely replaced the older combined ECPs because they are more effective and cause fewer side effects. Indeed, for many the dedicated progestin-only ECP has become synonymous with the phrase “emergency contraception.” Plan B One-Step®, NorLevo®, and Postinor UnoTM are just a few of the brand names for dedicated progestin-only products. Only the progestin levonorgestrel has been studied for freestanding use as an emergency contraceptive. The original treatment schedule that was studied and described in the medical literature was one 0.75mg dose within 72 hours after unprotected intercourse, and a second 0.75mg dose 12 hours after the first dose. However, recent studies have shown that a single dose of 1.5mg is as effective as two 0.75mg doses 12 hours apart (Arowojolu, Okewole, and Adekunle 2002; von Hertzen et al. 2002). One of these studies showed no difference in side effects between the two regimens (von Hertzen et al. 2002), while the other found greater levels of headache and breast tenderness (but not other side effects) among study participants taking 1.5mg of levonorgestrel at once (Arowojolu, Okewole, and Adekunle 2002). This is in contrast with combined ECPs, which have relatively high rates of side effects such as nausea and vomiting that may affect absorption of the drug. For this reason, the dosing for combined ECPs remains two doses, 12 hours apart, in order to avoid the increased side effects that would occur with a larger single dose. Increasingly, levonorgestrel is marketed internationally in a one-dose formulation (one 1.5mg pill) rather than the two-dose formulation. When dedicated progestin-only ECPs are not available, progestin-only OCPs (often referred to as mini pills) containing levonorgestrel may be used instead. ...