Emergency contraception (evidence relating to efficacy)

In the UK three forms of emergency contraceptives are currently recommended: (1)

• A copper intrauterine device (Cu-IUD).
• An oral progestogen-only emergency contraceptive (POEC) - levonorgestrel (LNG).
• A selective progesterone receptor modulator (SPRM) - ulipristal acetate (UPA) (3)

The Faculty of Sexual and Reproductive Healthcare (FSRH) guidelines for emergency contraception state: (1)

• clinicians should advise women that the Cu-IUD is the most effective emergency contraceptive. (1,2)
• a Cu-IUD can be inserted up to five days after the first UPSI in a natural menstrual cycle, or up to five days after the earliest likely date of ovulation (whichever is later).
• UPA-EC has been demonstrated to be more effective than LNG-EC.(1,2)
• the available evidence suggests that an oral emergency contraceptive administered after ovulation is ineffective.

Reference

1. Clinical Guidance: Emergency Contraception. Faculty of Sexual and Reproductive Healthcare (March 2017 - updated July 2023)
2. Practice Bulletin No. 152: Emergency Contraception. Obstet Gynecol. 2015 Sep;126(3):e1-e11.
3. Richardson AR, Maltz FN. Ulipristal acetate: review of the efficacy and safety of a newly approved agent for emergency contraception. Clin Ther. 2012 Jan;34(1):24-36.