Methods of Emergency Contraception

Cheng L, Gülmezoglu AM, Piaggio GGP, Ezcurra EE, Van Look PPFA

Published Online:

July 16, 2008

Emergency contraception is using a drug or copper intrauterine device (Cu-IUD) to prevent pregnancy after unprotected sex. This is for backup, not regular contraception. Mifepristone and levonorgestrel are very effective with few adverse effects, and are preferred to oestrogen and progestogen combined. Levonorgestrel could be used in a single dose (1.5 mg) instead of two split doses (0.75 mg) 12 hours apart. Another effective method for emergency contraception is Cu-IUD and it can be kept for ongoing contraception.

Abstract (click to read)

Background:

Emergency contraception is using a drug or copper intrauterine device (Cu-IUD) to prevent pregnancy shortly after unprotected intercourse. Several interventions are available for emergency contraception. Information on the comparative efficacy, safety and convenience of these methods is crucial for reproductive health care providers and the women they serve.

Objectives:

To determine which emergency contraceptive method following unprotected intercourse is the most effective, safe and convenient to prevent pregnancy.

Search strategy:

The search included the Cochrane Controlled Trials Register, Popline, MEDLINE, PubMed, Biosis/Embase, Chinese biomedical databases and UNDP/UNFPA/WHO/World Bank Special Programme on Human Reproduction (HRP) emergency contraception database (December 2006). Content experts and pharmaceutical companies were contacted.

Selection criteria:

Randomised controlled trials and controlled clinical trials including women attending services for emergency contraception following a single act of unprotected intercourse were eligible.

Data collection and analysis:

Data on outcomes and trial characteristics were extracted in duplicate and independently by two reviewers. Quality assessment was also done by two reviewers independently. Meta-analysis results are expressed as relative risk (RR) using a fixed-effects model with 95% confidence interval (CI). In the presence of statistically significant heterogeneity a random-effect model was applied.

Main results:

Eighty-one trials with 45,842 women were included. Most trials were conducted in China (70/81). There were more pregnancies with levonorgestrel compared to mid-dose (25-50 mg) (15 trials, RR: 2.01; 95% CI: 1.27 to 3.17) or low-dose mifepristone (<25 mg) (9 trials, RR: 1.43; 95% CI: 1.02 to 2.01). Low-dose mifepristone was less effective than mid-dose (20 trials, RR:0.67; 95% CI: 0.49 to 0.92), but this effect was no longer statistically significant when only high quality trials were considered (6 trials, RR: 0.75; 95% CI: 0.50 to 1.10). Single dose levonorgestrel (1.5 mg) administration seemed to have similar effectiveness as the standard 12 hours apart split-dose (0.75 mg twice) (2 trials, 3830 women; RR: 0.77, 95% CI: 0.45 to 1.30). Levonorgestrel was more effective than the Yuzpe regimen in preventing pregnancy (2 trials, RR: 0.51; 95% CI: 0.31 to 0.83). CDB-2914 (a second-generation progesterone receptor modulator) may be as effective as levonorgestrel (1 trial, 1549 women; RR:1.89; 95% CI: 0.75 to 4.64) but the conficence interval is wide and the result compatible with higher or lower effectiveness.

Delay in the onset of subsequent menses was the main unwanted effect of mifepristone and seemed to be dose-related.

Authors' conclusions:

Mifepristone middle dose (25-50 mg) was superior to other hormonal regimens. Mifepristone low dose (<25 mg) could be more effective than levonorgestrel 0.75 mg (two doses) but this was not conclusive. Levonorgestrel proved more effective than the Yuzpe regimen. The copper IUD was another effective emergency contraceptive that can provide ongoing contraception.

This record should be cited as:

Cheng L, Gülmezoglu AM, Piaggio GGP, Ezcurra EE, Van Look PPFA. Interventions for emergency contraception. Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD001324. DOI: 10.1002/14651858.CD001324.pub3

Assessed as up to date:

February 18, 2008

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Primary Review Group:

Fertility Regulation Group

Health topics:

Gynaecology > Contraception > Emergency contraception

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

Methods of Emergency Contraception

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