Intended for healthcare professionals

Practice Therapeutics

Emergency contraception

BMJ 2012; 344 doi: (Published 19 March 2012) Cite this as: BMJ 2012;344:e1492
  1. I Prabakar, subspecialty registrar in sexual and reproductive health1,
  2. A Webb, consultant in sexual and reproductive health1
  1. 1Abacus Services for Sexual and Reproductive Healthcare, Liverpool Community Health, Liverpool L2 5SF, UK
  1. Correspondence to: I Prabakar iprabakar{at}

A woman aged 22 requests “the morning after pill” for unprotected sexual intercourse 36 hours ago. You offer her a copper intrauterine device (IUD), ulipristal acetate, or levonorgestrel (table 1). She looks surprised and says she has never been offered a choice before: “Can’t I just have the pill I have taken before?”

View this table:
Table 1

Available formulations in the United Kingdom

What is emergency contraception?

Emergency contraception refers to contraception taken to prevent pregnancy after unprotected sexual intercourse or a potential contraceptive failure. The Omnibus survey 2008-9 from the Office for National Statistics showed that 7% of women in the United Kingdom had used emergency contraception in the previous year.1 This update focuses on the currently available choices for women requesting postcoital contraception.

Available methods

Women in the UK currently have three choices (table 1)2:

  • Levonorgestrel (a progestogen) 1.5 mg, which is licensed up to three days (72 hours) after unprotected sexual intercourse

  • Ulipristal acetate (a progesterone receptor modulator) 30 mg, which is licensed for use up to five days (120 hours) after unprotected sexual intercourse3

  • A copper IUD fitted up to five days after unprotected sexual intercourse or ovulation, whichever is longer.

The Yuzpe method, a combined oestrogen and progestogen emergency contraceptive, has more side effects and is no longer used when a progestogen only alternative is available. Mifepristone has been studied but is currently available only in China and Vietnam. There is no evidence to support the use of a levonorgestrel intrauterine system as an emergency contraceptive.

How does it work?

Intrauterine device

IUDs work by being toxic to the ovum and sperm and preventing fertilisation when used as ongoing contraception, but when fitted after fertilisation they also have an anti-implantation effect (table 2; fig 1).2 4

Fig 1 Window of action of different emergency contraceptive methods in relation to ovulation

View this table:
Table 2

Mechanism …

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