Press Release WHO/58
7 August 1998
EMBARGOED UNTIL 7 AUGUST 1998 AT 00.01h GMT
LEVONORGESTREL FOR EMERGENCY CONTRACEPTION IS MORE EFFECTIVE AND HAS FEWER SIDE-EFFECTS THAN THE YUZPE REGIMEN
In a paper published in the 8 August issue of the journal The Lancet, researchers working with the UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP) confirm that the use of levonorgestrel alone for emergency contraception is more effective and produces side-effects in considerably fewer users than the Yuzpe regimen currently the most widely used method for such contraception.
According to Dr Paul F.A. Van Look, Director HRP, "Unplanned pregnancies are a major problem worldwide as many end up in being terminated through unsafe abortion, which is responsible for the deaths of some 80000 women every year and causes lifelong debilitating illness for tens of thousands more. Our study confirms that an existing, well-tested compound can be used easily and safely to prevent a great number of such unplanned pregnancies."
Levonorgestrel is a synthetic derivative of the hormone progesterone. It is one of the two active compounds in combined oral contraceptive pills. In the regimen used for emergency contraception, two pills, each containing 0.75 mg of levonorgestrel, are administered at an interval of 12 hours.
The Yuzpe method of emergency contraception, which is the method currently in use, was developed in the early 1980s. It is based on a modified regimen of combined oral contraceptive pills i.e. oral contraceptives that contain an oestrogen and a progestogen. In the Yuzpe regimen also two doses are administered with an interval of 12 hours. Each dose contains 100 micrograms of the synthetic estrogens ethinylestradiol and 0.5 mg of levonorgestrel.
The study published in The Lancet was conducted by HRP in 21 centres around the world and involved 1998 women. It sought to compare the efficacy of the two methods (the Yuzpe regimen and levonorgestrel) when treatment is started within 72 hours of unprotected sex. All women included in the study had requested emergency contraception after a single act of unprotected sexual intercourse. Each woman received either levonorgestrel or the Yuzpe regimen and, as the study was double blind, neither the clinicians nor the women knew what treatment they had received.
The overall method failure rate i.e. percentage of women who became pregnant in spite of taking the treatment was higher in the group that received the Yuzpe regimen, being 3.2%, as compared to 1.1% among those who received levonorgestrel. Calculations of the number of pregnancies that could have occurred if no treatment had been given showed that levonorgestrel had prevented 85% of unintended pregnancies as compared to 57% with the Yuzpe regimen.
In both groups of women, the earlier the treatment was started the lower was the pregnancy rate. For example, among the women who started treatment within 24 hours, levonorgestrel prevented 95% of the pregnancies that would have occurred if no treatment had been given, compared with 77% for the Yuzpe method. Among those who started with their treatment between 25 hours and 48 hours, the success rate in the levonorgestrel group was 85% whereas it was only 38% in the Yuzpe group. Even beyond 48 hours, levonorgestrel was effective in preventing pregnancy in more than 60% of cases compared with 38% for the Yuzpe method.
Apart from being more efficacious, levonorgestrel was also much better tolerated by the women than the Yuzpe regimen. The women for both methods reported the same side effects. These include: nausea, vomiting, dizziness, fatigue, headache, breast tenderness and low abdominal pain. For each of these side-effects women taking levonorgestrel reported them far less frequently than those taking the Yuzpe regimen. In the case of nausea, vomiting, dizziness, and fatigue the difference was substantial and statistically significant. For example, half the women taking the Yuzpe method reported nausea whereas only a quarter of those taking levonorgestrel reported it. Moreover, vomiting occurred in nearly 20% of the women taking the Yuzpe method, while in those taking levonorgestrel it occurred in only 6% of cases.
Dr Helena von Hertzen, Medical Officer at HRP, says, "This study has clearly demonstrated that levonorgestrel outperforms the Yuzpe method in both efficacy and tolerance by users. We believe these findings will persuade health services already offering emergency contraception to start offering levonorgestrel instead of or in addition to the Yuzpe method. The results of this study may also prompt health services not yet providing emergency contraception to consider doing so."
For further information, journalists can contact Jitendra Khanna, Special Programme for Research Training in human Reproduction, WHO, Geneva. Telephone (41 22) 791 3345. Fax (41 22) 791 4171. Email: firstname.lastname@example.org
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