In clinical practice emergency contraception (EC) intends to suppress follicular development, ovulation, or the ability of a conceptus to implant. Exogenous steroids, estrogen and progestin, are used in various formulations to accomplish the suppression. Though EC are now available 'over-the-counter' in Canada and many countries around the world; the ovarian response is unpredictable and EC do not inhibit ovulation at the most critical times of the menstrual cycle. In 2002 approximately 120,000 of 450,000 pregnancies in Canada ended in elective pregnancy termination. In the US 49% of the 3.5 million annual pregnancies were unintended and 54% of the unintended pregnancies resulted in elective termination.