Emergency contraceptive pills and weight

Manufacturer of emergency contraceptive pill warns of effectiveness in overweight women. By Kirsten Braun

pdfHealth_Journey_2014_1.pdf

tape measure resizedHRA Pharma, the manufacturer of emergency contraceptive pill (ECP) NorLevo, recently announced that they were updating their packaging information to warn women it was not recommended for women over 75 kilograms. NorLevo contains the progestogen levonorgestrel.

What about other brands of ECP?
Levonorgestrel is also the active ingredient in other brands of ECP sold in Australia, Postinor and Levonelle. The Therapeutic Goods Administration (TGA) is currently reviewing the information to determine whether any other action is required in Australia, and if so, whether the patient information for all brands of ECP should be updated.

What led to the manufacturer changing their information?
HRA Pharma was prompted to look at the effectiveness of their drug following the publication of a study in Contraception in 2011. This meta-analysis found the risk of pregnancy for women taking ECP was threefold greater for obese women and 1.5 times greater for overweight women compared with women with a normal body mass index. The study authors found levonorgestrel "showed a rapid decrease of efficacy with increasing BMI reaching the point where it appeared no different from pregnancy rates expected among women not using EC at a BMI of 26kg/m²". According to the World Health Organization, overweight women are between 25 and 30kg/m²and obese women are 30kg/m² and above.

However, the study authors also explained that the meta-analysis was based on two randomised controlled trials, neither of which was specifically set up to investigate weight and its impact on the effectiveness of ECP. In addition, the number of pregnancies in overweight and obese women was relatively small, 13 and 20 respectively. There is, therefore, a real need for a large randomised controlled trial specifically examining weight and the effectiveness of levonorgestrel.

What does it mean for women?
Women requiring emergency contraception who are obese or overweight may wish to also consider the use of a copper intra-uterine device (IUD). Copper IUDs prevent 99% of pregnancies if inserted within 5 days and provide women with ongoing contraception. However, copper IUDs need to be inserted by a skilled health professional making this option difficult to access within the required time frame. In addition, many women are not accepting of IUDs and would not find this a satisfactory alternative. Another more effective ECP, ulipristal acetate, is not yet available in Australia. In the absence of larger studies into weight and ECP and the lack of ulipristal acetate as an alternative ECP, women who are overweight or obese should access the levonorgestrel ECP rather than leave it to chance.

All women requiring ECP should access it as soon as possible, within 72 hours after unprotected sex, but ideally within 24 hours. ECP can be taken up to five days after unprotected sex but are not particularly effective after four days. ECP can be obtained over the counter from most chemists.

If women who take ECP find their period is more than seven days late they should follow up with a pregnancy test to determine if they are pregnant.

The importance of long-term contraception
In the Contraception meta-analysis, 20% of the women had further unprotected sex, making them more than four times more likely to become pregnant than women who did not report further unprotected sex. It is important, therefore, that after the first episode of unprotected sex women do not place themselves at risk of pregnancy again by choosing a reliable form of contraception to use longer term.

Last Updated: April 2014

Women's Health Queensland Wide Inc. This article was written by Kirsten Braun and reviewed by the Women's Health Queensland Wide editorial committee. It was published in pdfHealth Journey 2014 Issue 1.1.08 MB

Tags: 

The content of this publication ("the information") is provided for information purposes only. The information is provided solely on the basis that recipients should verify all the information provided. The information is not intended to be used to diagnose, treat, cure or prevent any disease or condition, nor should it be used for therapeutic or clinical care purposes. The information is not a substitute for your own health professional's advice and treatment in relation to any specific patient issue. Women's Health Queensland Wide Inc. does not accept any liability for any injury, loss or damage incurred by the use of or reliance on the information. While we have made every effort to ensure the information is accurate, complete and current, Women's Health Queensland Wide Inc. does not guarantee and assumes no legal liability or responsibility for the accuracy, currency or completeness of the information. External resources referred to in this publication should not be taken to be an endorsement or a recommendation of any third party products or services offered and the views or recommendations provided by these external resources do not necessarily reflect those of Women's Health Queensland Wide Inc.