How do levonorgestrel-only emergency contraceptive pills prevent pregnancy? Some considerations

References

• International Consortium for Emergency Contraception (ICEC), International Federation of Gynecology & Obstetrics (FIGO). Statement on mechanism of action (October 2008). http://www.figo.org/news/joint-statement-international-consortium-emergency-contraception.
   Google Scholar
• Marions L, Hultenby K, Lindell I, Sun X, Stabi B, Gemzell Danielsson K. Emergency contraception with mifepristone and levonorgestrel: mechanism of action. Obstet Gynecol 2002;100:65–71.
   PubMed Web of Science ®Google Scholar
• Durand M, del Carmen Cravioto M, Raymond EG, Duran-Sanchez O, De la Luz Cruz-Hinojosa M, Castell-Rodriguez A, Schiavon R, Larrea F. On the mechanisms of action of short-term levonorgestrel administration in emergency contraception. Contraception 2001;64:227–234.
   PubMed Web of Science ®Google Scholar
• Hapangama D, Glasier AF, Baird DT. The effects of peri-ovulatory administration of levonorgestrel on the menstrual cycle. Contraception 2001;63:123–129.
   PubMed Web of Science ®Google Scholar
• Marions L, Cekan SZ, Bygdeman M, Gemzell-Danielsson K. Effect of emergency contraception with levonorgestrel or mifepristone on ovarian function. Contraception 2004;69:373–377.
   PubMed Web of Science ®Google Scholar
• Croxatto HB, Brache V, Pavez M, Cochon L, Forcelledo ML, Alvarez F, Massai R, Faundes A, Salvatierra AM. Pituitary-ovarian function following the standard levonorgestrel emergency contraceptive dose or a single 0.75 mg dose given on the days preceding ovulation. Contraception 2004;70:442–450.
   PubMed Web of Science ®Google Scholar
• Okewole IA, Arowojolu AO, Odusoga OL, Oloyede OA, Adeleye OA, Salu J, Dada OA. Effect of single administration of levonorgestrel on the menstrual cycle. Contraception 2007;75:372–377.
   PubMed Web of Science ®Google Scholar
• Croxatto HB, Devoto L, Durand M, Ezcurra E, Larrea F, Nagle C, Ortiz ME, Vantman D, Vega M, von Hertzen H. Mechanism of action of hormonal preparations used for emergency contraception: a review of the literature. Contraception 2001;63:111–121.
   PubMed Web of Science ®Google Scholar
• Novikova N, Weisberg E, Stanczyk FZ, Croxatto HB, Fraser IS. Effectiveness of levonorgestrel emergency contraception given before or after ovulation – a pilot study. Contraception 2007:75:112–118.
   PubMed Web of Science ®Google Scholar
• Meng CX, Andersson KL, Bentin-Ley U, Gemzell-Danielsson K, Lalitkumar PG. Effect of levonorgestrel and mifepristone on endometrial receptivity markers in a three-dimensional human endometrial cell culture model. Fertil Steril 2009;91:256–264.
   PubMed Web of Science ®Google Scholar
• Durand M, Seppala M, Cravioto M del C, Koistinen H, Koistinen R, Gonzalez-Macedo J, Larrea F. Late follicular phase administration of levonorgestrel as an emergency contraceptive changes the secretory pattern of glycodelin in serum and endometrium during the luteal phase of the menstrual cycle. Contraception 2005;71:451–457.
   PubMed Web of Science ®Google Scholar
• Lalitkumar PG, Lalitkumar S, Meng CX, Stavreus-Evers A. Hambiliki F, Bentin-Ley U, Gemzell-Danielsson K. Mifepristone, but not levonorgestrel, inhibits human blastocyst attachment to an in vitro endometrial three-dimensional cell culture model. Hum Reprod 2007;22:3031–3037.
   PubMed Web of Science ®Google Scholar
• Müller A, Llados C, Croxatto HB. Postcoital treatment with levonorgestrel does not disrupt postfertilization events in the rat. Contraception 2003;67:415–419.
   PubMed Web of Science ®Google Scholar
• Ortiz ME, Ortiz RE, Fuentes A, Parraguez VH, Croxatto HB. Post-coital administration of levonorgestrel does not interfere with post-fertilization events in the new world monkey Cebus apella. Hum Reprod 2004;19:1352–1356.
   PubMed Web of Science ®Google Scholar
• Kesseru E, Camacho-Ortega P, Laudahn G, Schopflin G. In vitro action of progestogens on sperm migration in human cervical mucus. Fertil Steril 1975;26:57–61.
   Google Scholar
• Kesseru E, Garmendia F, Westphal N, Parada J. The hormonal and peripheral effects of d-norgestrel in postcoital contraception. Contraception 1974;10:411–424.
   PubMed Web of Science ®Google Scholar
• Munuce MJ, Nascimento JAA, Rosano G, Faundes A, Bahamondes L. Doses of levonorgestrel comparable to that delivered by the levonorgestrel releasing intrauterine system can modify the in vitro expression of zona binding sites of human spermatozoa. Contraception 2006;73:97–101.
   PubMed Web of Science ®Google Scholar
• Do Nascimento JA, Seppalla M, Perdigao A, Espejo-Arce X, Munuce MJ, Hautala L, Koistinen R, Andrade L, Bahamondes L. In vivo assessment of the human sperm acrosome reaction and the expression of glycodeling-A in human endometrium after levonorgestrel-emergency contraceptive pill administration. Hum Reprod 2007;22:2190–2195.
   PubMed Web of Science ®Google Scholar
• De Santis M, Cavaliere AF, Straface G, Carducci F, Caruso A. Failure of the emergency contraceptive levonorgestrel and the risk of adverse effects in pregnancy and on fetal development: an observational cohort study. Fertil Steril 2005;84:296–299.
   PubMed Web of Science ®Google Scholar
• Bigrigg A, Evans M, Gbolade B, Newton J, Pollard L, Szarewski A, Thomas C, Walling M. Depo Provera: position paper on clinical use, effectiveness and side effects. Br J Fam Plan 1999;25:69–76.
   PubMedGoogle Scholar
• Yeung WSB, Chiu PCN, Wang CH, Yao YQ, Ho P. The effects of levonorgestrel on various sperm functions. Contraception 2002;66:453–457.
   PubMed Web of Science ®Google Scholar
• Cohen BJ, Rein te Velde E, Scheffer G, Van Kooij RJ, De Brouwer CPM, Van Zonneveld P. The pattern of the luteinizing hormone surge in spontaneous cycles is related to the probability of conception. Fertil Steril 1993;60:413–417.
   Google Scholar