Turok DK. Unprotected intercourse in the 2 weeks prior to requesting emergency intrauterine contraception. American journal of obstetrics and gynecology. 2016 Nov;215(215). 592.e1-592.e5. PMID: 27349294 [PubMed]
Previous emergency contraception studies have excluded women who report >1 episode of unprotected or underprotected intercourse. Thus, clinical recommendations are based on exposure to a single episode of underprotected intercourse.