A Cost-Effective Approach to Preventing Unintended Pregnancy
James Trussell, PhD1 Elizabeth G. Raymond, MD, MPH2 March 2007
Professor of Economics and Public Affairs and Director, Office of Population Research, Princeton University, Wallace Hall, Princeton University, Princeton NJ 08544. Tel: 609-258-4946, Fax: 609-258-1039, Email: firstname.lastname@example.orgAssociate Medical Director, Biomedical Affairs Division, Family Health International. PO Box 13950, Research Triangle Park, NC 27709. Tel: 919-544-7040; Fax: 919-544-7261; Email: email@example.com
The authors have no personal financial interest whatsoever in the commercial success or failure of emergency contraception.
Introduction Half of all pregnancies in the United States are unintended:there were 3.1 million in 2001 alone, the last year for which data are available. 1 Emergency contraception, which prevents pregnancy after unprotected sexual intercourse, has the potential to reduce significantly the incidence of unintended pregnancy and the consequent need for abortion. 2 Emergency contraception is especially important for outreach to the 4.6 million women at risk of pregnancybut not using a regular method 3 by providing a bridge to use of an ongoing contraceptive method. Although emergency contraceptives do not protect against sexually transmitted infection, they do offer reassurance to the 6.8 million women who rely on condoms for protection against pregnancy in case of condom slippage or breakage. Emergency contraceptives available in the United States includeemergency contraceptive pills and the Copper T intrauterine device (IUD). 4, 5 , 6 Emergency contraceptive pills There are two types of emergency contraceptive pills (ECPs): combined ECPs containing both estrogen and progestin and progestin-only ECPs. The newer progestin-only ECPs have now largely replaced the older combined ECPs because they are more effective and cause fewer side effects. Although thistherapy is commonly known as the morning-after pill, the term is misleading; ECPs may be initiated sooner than the morning after—immediately after unprotected intercourse—or later—for at least 120 hours after unprotected intercourse. Progestin-only ECPs contain no estrogen. Only the progestin levonorgestrel has been studied for freestanding use as an emergency contraceptive. The originaltreatment schedule was one 0.75 mg dose within 72 hours after unprotected intercourse, and a second 0.75 mg dose 12 hours after the first dose. However, recent studies have shown that a single dose of 1.5 mg is as effective as and causes no more side effects than two 0.75 mg doses 12 hours apart. 7,8 (Another study found that two 0.75 mg doses 24 hours apart were just as effective as two 0.75 mg doses 12hours apart. 9 ) The only progestin-only product available in the United States is Plan-B, approved by the FDA as an ECP in July 1999 (Table 1). Combined ECPs are ordinary birth control pills containing the hormones estrogen and progestin. The hormones that have been studied extensively in clinical trials of ECPs are the estrogen ethinyl estradiol and the progestin levonorgestrel or norgestrel(which contains two isomers, only one of which—levonorgestrel—is bioactive). These are found in 19 brands of combined oral contraceptives available in the United States (Table 1). 10 One specially-packaged ECP product (Preven) was approved by the FDA in 1998 but withdrawn from the market in 2004. This combination of active ingredients used in this way is also sometimes called the Yuzpe method, afterthe Canadian physician who first described the regimen. Newer research has demonstrated the safety and efficacy of an alternative regimen containing ethinyl estradiol and the progestin norethindrone; 11 this result suggests that oral contraceptive pills containing progestins other than levonorgestrel may be used for emergency contraception when the two standard regimes are not available....