Emergency contraception should be considered for women at risk of unintended pregnancy after unprotected intercourse
There are two methods of emergency contraception: the copper intrauterine device and hormonal emergency contraception using levonorgestrel (a progestin) or ulipristal acetate (a selective progesterone receptor modulator). All methods act before implantation (Appendix 1, available at www.cmaj.ca/lookup/suppl/doi:10.1503/cmaj.160720/-/DC1).1
The copper intrauterine device is the most effective method and a first-line option for most women
The copper intrauterine device is 99.9% effective when used within seven days of unprotected intercourse. 2 It is suitable for most women, including those who have never given birth and adolescents. Contraindications are the same as when used for regular contraception. Testing for sexually transmitted infection can be done at time of insertion of the device.
Hormonal emergency contraception is easier to access but less effective than the copper intrauterine device
Although most effective when taken immediately, both levonorgestrel and ulipristal have some effect if taken up to five days after unprotected intercourse.2 Ulipristal is somewhat more effective than levonorgestrel, with pregnancy rates of 1.3% v. 2.2%, respectively, when used within 120 hours of intercourse.2,4 Use of ulipristal is not recommended in women using emergency contraception because of missed hormonal contraception.3
An elevated body mass index may decrease the effectiveness of hormonal emergency contraception but has no impact on the copper intrauterine device
Although still being studied, levonorgestrel may be less effective in patients with a body mass index (BMI) of 25 kg/m2 or more, whereas ulipristal appears to be effective in patients with a BMI up to 35 kg/m2.2,5 If a copper intrauterine device is not an option, hormonal emergency contraception should be offered regardless of BMI (preferably ulipristal).
Women using hormonal emergency contraception need a plan for ongoing contraception
Hormonal contraception can be started immediately after levonorgestrel; however, it should be delayed until five days after use of ulipristal to not interfere with the action of ulipristal. 2 Back-up contraception is needed until hormonal contraception has been used for seven days.2,3 In the absence of menses within three to four weeks after emergency contraception, pregnancy should be excluded. (Patient information on emergency contraception is available at www.whatsnextforme.ca).
Acknowledgement
The authors thank Dr. Edith Guilbert and the Women’s College Hospital Family Medicine Peer Support Writing Group for their guidance in the production of this article.
Footnotes
Competing interests: Sheila Dunn is a coauthor of the emergency contraception chapter of the Canadian Contraceptive Consensus published in 2015. No other competing interests were declared.
This article has been peer reviewed.
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- Emergency contraception should be considered for women at risk of unintended pregnancy after unprotected intercourse
- The copper intrauterine device is the most effective method and a first-line option for most women
- Hormonal emergency contraception is easier to access but less effective than the copper intrauterine device
- An elevated body mass index may decrease the effectiveness of hormonal emergency contraception but has no impact on the copper intrauterine device
- Women using hormonal emergency contraception need a plan for ongoing contraception
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