Emerging options for emergency contraception

Abstract

Emergency post-coital contraception (EC) is an effective method of preventing pregnancy when used appropriately. EC has been available since the 1970s, and its availability and use have become widespread. Options for EC are broad and include the copper intrauterine device (IUD) and emergency contraceptive pills such as levonorgestrel, ulipristal acetate, combined oral contraceptive pills (Yuzpe method), and less commonly, mifepristone. Some options are available over-the-counter, while others require provider prescription or placement. There are no absolute contraindications to the use of emergency contraceptive pills, with the exception of ulipristal acetate and mifepristone. This article reviews the mechanisms of action, efficacy, safety, side effects, clinical considerations, and patient preferences with respect to EC usage. The decision of which regimen to use is influenced by local availability, cost, and patient preference.

Keywords: emergency contraception; emergency contraceptive pills; intrauterine device; levonorgestrel.

Figure 1

Diagram of hormonal fluctations in the menstrual cycle. Notes: Day 0 of the menstrual cycle is the first day of menstruation. During the follicular phase LH and FSH (both released by the anterior pituitary) levels begin to rise, and peak at approximately day 14, as an egg is released from the lead follicle (top picture). The ‘fertile period’ begins approximately 5 days before the LH surge, and ends the day after, as the egg rapidly degenerates if not fertilized. LNG and the Yuzpe regimen are effective only if given before the LH surge. UPA continues to be effective until the LH surge peaks. The copper IUD continues to be effective throughout the cycle. Menstrual cycle times can vary widely by individual, thus making exact timing of the fertile period difficult to calculate.