Weight may diminish efficacy

Answer: Levonorgestrel may not be effective for emergency contraception (EC) in women weighing more than 70kg. 1 Levonorgestrel (NorLevo-1, NorLevo, Postinor, Levonelle) is recommended for use as an oral EC used as a single dose of 1.5mg within 72 hours of unprotected sexual intercourse. 2,3 When taken within 48 hours of intercourse, levonorgestrel is estimated to prevent 85% of expected pregnancies, dropping to 58% by 72 hours. 4

A 2011 study reported that effectiveness of levonorgestrel in preventing