US FDA announcement on LNG EC efficacy and weight
On May 24, 2016, the United States Food and Drug Administration (FDA) announced completion of a review of the existing data related to the efficacy of EC and body weight, concluding that the data do not warrant a change to product labels:
“The FDA has completed a review of available scientific data concerning the effectiveness of levonorgestrel (LNG) emergency contraceptives (ECs) in women who weigh more than 165 pounds or have a body mass index (BMI) above 25 kg/m2. The data are conflicting and too limited to reach a definitive conclusion as to whether effectiveness is reduced in this group. The FDA does not believe that a change in the labeling for LNG EC products is warranted at this time. There are no safety concerns that preclude use of LNG ECs in women generally, and the FDA continues to believe that all women, regardless of how much they weigh, can use these products to prevent unintended pregnancy following unprotected sexual intercourse or contraceptive failure. The most important factor affecting how well emergency contraception works is how quickly it is taken after unprotected sex.”
The announcement recommends that further research by manufacturers of LNG EC on the potential impact of body weight on effectiveness of the product should be a priority.
ECEC’s 2015 statement on this issue reached a similar conclusion, and can be accessed here: Efficacy of emergency contraception and body weight: Current understanding and recommendations. In this statement, ECEC acknowledges that while there may be an association between the effectiveness of EC pills and the weight or BMI of the user, the available data are not sufficient to support a change to product labels. We note that the copper IUD followed by UPA EC are the most effective forms of EC for all women, regardless of weight, but that women should be not be denied LNG EC because of their weight.
For more information from the FDA, please read: