Abstract and Introduction
Abstract
BACKGROUND Intrauterine devices (IUDs) have been studied for use for emergency contraception for at least 35 years. IUDs are safe and highly effective for emergency contraception and regular contraception, and are extremely cost-effective as an ongoing method. The objective of this study was to evaluate the existing data to estimate the efficacy of IUDs for emergency contraception.
METHODS The reference list for this study was generated from hand searching the reference lists of relevant articles and our own article archives, and electronic searches of several databases: Medline, Global Health, Clinicaltrials.gov, Popline, Wanfang Data (Chinese) and Weipu Data (Chinese). We included studies published in English or Chinese, with a defined population of women who presented for emergency contraception and were provided with an IUD, and in which the number of pregnancies was ascertained and loss to follow-up was clearly defined. Data from each article were abstracted independently by two reviewers.
RESULTS The 42 studies (of 274 retrieved) that met our inclusion criteria were conducted in six countries between 1979 and 2011 and included eight different types of IUD and 7034 women. The maximum timeframe from intercourse to insertion of the IUD ranged from 2 days to 10 or more days; the majority of insertions (74% of studies) occurred within 5 days of intercourse. The pregnancy rate (excluding one outlier study) was 0.09%.
CONCLUSIONS IUDs are a highly effective method of contraception after unprotected intercourse. Because they are safe for the majority of women, highly effective and cost-effective when left in place as ongoing contraception, whenever clinically feasible IUDs should be included in the range of emergency contraception options offered to patients presenting after unprotected intercourse. This review is limited by the fact that the original studies did not provide sufficient data on the delay between intercourse and insertion of the IUD, parity, cycle day of intercourse or IUD type to allow analysis by any of these variables.
Introduction
Unintended pregnancy is a significant problem worldwide. It is estimated that globally at least 36% of pregnancies are unintended (Singh et al., 2009), and in the USA nearly half of pregnancies are unintended (Finer and Zolna, 2011). Emergency contraception offers women an important strategy to prevent pregnancy after intercourse in cases of contraceptive accidents or non-use, or in situations of sexual violence. There are two forms of emergency contraception available today: pills and intrauterine devices (IUDs). The most common medication option is 1.5 mg levonorgestrel, sold in one-pill or two-pill formulations. A newer formulation is 30 mg ulipristal acetate, marketed in the USA as ella® and in much of Europe as ellaOne®. In a few places, such as China, Vietnam and Russia, mifepristone in small doses is available for emergency contraception.
Non-hormonal IUDs (primarily copper-bearing) have been used for emergency contraception for at least 35 years (Lippes et al., 1976). (The levonorgestrel intrauterine system, sold in the USA and Europe under the brand name Mirena®, has not been studied for use for emergency contraception.) Negative experiences with the Dalkon Shield, an IUD available in the 1970s in the USA, led to years of concern about the safety of IUDs and very low levels of IUD use. However, the design of modern IUDs available today is vastly improved, and guidelines from major medical organizations, such as the Centers for Disease Control and Prevention, the World Health Organization, the UK Faculty of Sexual and Reproductive Healthcare and American College of Obstetricians and Gynecologists, note that IUDs are a safe choice for the majority of patients, including young and nulliparous women (World Health Organization, 2009; ACOG Practice Bulletin, 2010; Centers for Disease Control and Prevention, 2010; Faculty of Sexual & Reproductive Healthcare, Clinical Effectiveness Unit, 2011).
One of the major advantages of copper IUDs is that following use for emergency contraception, they can then be left in place to provide at least 10 years of highly effective ongoing contraception. [In the USA ParaGard® is labeled for 10 years of use but there is evidence of efficacy with longer use (Dean and Schwarz, 2011).] IUDs have been shown to be among the most cost-effective methods of contraception (Trussell et al., 2009); the fact that this is a 'forgettable' method that does not require action on the part of the user means that there is virtually no scope for user error.
IUDs are experiencing a moderate comeback after years of very low uptake in the USA (Hubacher et al., 2011). In 2008 (the last year for which data are available), 4.9% of American women at risk of pregnancy reported using an IUD (Mosher and Jones, 2010). This is a marked increase from the 0.7% of women at risk of pregnancy choosing IUDs in 1995 (Mosher and Jones, 2010) but is still lower than the use in Europe, where 10% of British women (data from 2009) (Lader, 2009) and 24% of French women (data from 2005) (Moreau et al., 2008) at risk of pregnancy use IUDs. No comparable statistic is available for IUD use among all women at risk of pregnancy in China, but the Chinese National Population and Family Planning Commission reported that 53% of married women using contraception used IUDs in 2009 (National Population and Family Planning Commission, Population and Development Research Center of China, 2010). IUD use is higher in China than in the world overall; a 2005 report noted that 43% of Chinese women using contraception used IUDs, compared with 13% in the rest of the world (Salem, 2006). Guidelines for the use of IUDs for emergency contraception typically recommend inserting the IUD within 5 days of unprotected intercourse (ACOG Practice Bulletin, 2010), although the Centers for Disease Control, the World Health Organization and the UK Faculty of Sexual and Reproductive Healthcare specify that an IUD can be used beyond 5 days, as long as the time of ovulation can be reasonably determined and the insertion occurs no more than 5 days after ovulation (World Health Organization, 2009; Centers for Disease Control and Prevention, 2010; Faculty of Sexual & Reproductive Healthcare, Clinical Effectiveness Unit, 2011). It should be noted that the guidelines around the time of insertion are not related to efficacy or safety but to ensure that the IUD is inserted before the implantation of an embryo (thus ensuring its function as a contraceptive, rather than an early abortifacient).