In Europe, a morning-after pill identical to Plan B is going to come with a warning— the manufacturer has found the drug is ineffective for women who weigh more than 176 pounds, and begins to lose effectiveness in women who weigh more than 165 pounds. The average American woman weighs 166.2 pounds.
And its unclear whether women in the U.S. will know about this warning even though it applies to them. Mother Jones' Molly Redden reports:
HRA Pharma, the French manufacturer of the European drug, Norlevo, is changing its packaging information to reflect the weight limits. European pharmaceutical regulators approved the change on November 10, but it has not been previously reported.
... Some of the most popular emergency contraceptive pills sold over-the-counter in the United States—including the one-pill drugs Plan B One-Step, Next Choice One Dose, and My Way, and a number of generic two-pill emergency contraceptives—have a dosage and chemical makeup identical to the European drug.
In short: there may be women who are using a morning-after pill that's not working the way it should be, ergo, not preventing a pregnancy the way it should be. Further, it seems that Plan B, Norlevo, and their generic counterparts do as much for heavier women's contraception as a glass of water.
If these studies are correct (they seem sturdy enough for a drug company to issue a warning) is particularly troubling for a large number of American women. According to numbers compiled by the CDC, the average American woman over the age of 30 would fall under the pill's warning of diminishing ineffectiveness (the number on the right is the weight of the women in pounds):