Lots of reports swirling that the European version of the morning-after-pill called Norlevo is reduced effective for women 166+ pounds and entirely ineffective for those carrying 176+ pounds.

Apparently the chemical recipe of the medication in question mirrors that of popular US versions including Plan B One-Step, Next Choice One Dose, and My Way.
Mother Jones has reported this information from an FDA spokesman who indicated they are evaluating a label change requirement for US manufacturers.
Given that the average weight of American women ages 20+ lies just over 166 pounds, this would mean half the population are not viable candidates for this method of contraception. From 2006 to 2010, a CDC survey reports around 6 million American ladies used emergency contraception.

pro-plan-now suggests all women always being armed in advance for intimacy and not relying on such medications.
Contraception: It’s okay to talk about it!