Definition of "levonorgestrel" [levonorgestrel]

• The levorotatory form of norgestrel, used in oral contraceptives and in contraceptives implanted subdermally. In implant form it can prevent pregnancy for up to five years. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "However, the FDA said two recently published studies reported a greater risk of blood clots for women taking birth-control pills containing drospirenone, compared to birth-control pills containing another progestin known as levonorgestrel."
• "The studies - both published Thursday in the online edition of the British Medical Journal - show that pills containing a new type of progestogen hormone called drospirenone carry up to triple the risk of serious blood clots known as venous thromboembolisms over an older generation of pills containing a hormone called levonorgestrel."
• "The most widely used emergency contraceptive drug is levonorgestrel, which is approved for use within 72 hours of sexual intercourse and is thought to work by interfering with ovulation, the release of eggs from the ovaries."