November 25, 2013

A Weighty Question: Does “Plan B” have a Weight Limit?

iStockphoto/Thinkstock Mother Jones today has a great piece out on how a version of “Plan B” manufactured in Europe is less effective for women who weigh more than 165 pounds, and rendered completely ineffective for women whose weight tops 176 pounds.

By Dina Fine Maron

Join Our Community of Science Lovers!

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

: iStockphoto/Thinkstock

Mother Jones today has a great piece out on how a version of "Plan B" manufactured in Europe is less effective for women who weigh more than 165 pounds, and rendered completely ineffective for women whose weight tops 176 pounds. (The average adult American woman weighs in at 166.2 pounds, notes CDC.) Though the European drug, Norlevo, is not licensed under that brand name for use here in the United States, I’ll be keeping my eyes out to see what happens to emergency contraception in the United States, which includes similar levels of synthetic hormones.

When the U.S.-version of Plan B was originally approved in 1999, it did not include any assessment specific to a woman’s weight. I reached out to FDA for further guidance on the future of emergency contraception in the United States. In an email, the agency states: “The FDA is currently reviewing the available and related scientific information on this issue, including the publication upon which the Norlevo labeling change was based. The agency will then determine what, if any, labeling changes to approved emergency contraceptives are warranted.”

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American