Postfertilization Effect of Hormonal Emergency Contraception

Kahlenborn, Chris; Stanford, Joseph B.; Larimore, Walter L.

doi:10.1345/aph.1a344

Cited by 39 publications

(25 citation statements)

References 43 publications

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“…Our findings confirm and extend earlier reviews of the topic suggesting that post-fertilization MOA of LNG-EC play a not negligible and possibly dominant role (Peck and Velez 2013;Mozzanega and Cosmi 2011;Kahlenborn, Stanford, and Larimore 2002).…”

Section: Introductionsupporting

confidence: 91%

Does Levonorgestrel Emergency Contraceptive have a Post-Fertilization Effect? A Review of its Mechanism of Action

Peck

Rella²,

Tudela

et al. 2016

Linacre Q

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Background: Recent studies have identified that levonorgestrel administered orally in emergency contraception (LNG-EC) is only efficacious when taken before ovulation. However, the drug does not consistently prevent follicular rupture or impair sperm function. Objective: The present systematic review is performed to analyze and more precisely define the extent to which pre-fertilization mechanisms of action may explain the drug's efficacy in pregnancy avoidance. We also examine the available evidence to determine if pre-ovulatory drug administration may be associated with post-fertilization effects. Conclusion: The mechanism of action of LNG-EC is reviewed. The drug has no ability to alter sperm function at doses used in vivo and has limited ability to suppress ovulation. Our analysis estimates that the drug's ovulatory inhibition potential could prevent less than 15 percent of potential conceptions, thus making a pre-fertilization mechanism of action significantly less likely than previously thought. Luteal effects (such as decreased progesterone, altered glycodelin levels, and shortened luteal phase) present in the literature may suggest a pre-ovulatory induced post-fertilization drug effect. Lay Summary: Plan B is the most widely used emergency contraceptive available. It is important for patients and physicians to clearly understand the drug's mechanism of action (MOA). The drug was originally thought to work by preventing fertilization. Recent research has cast doubt on this. Our review of the research suggests that it could act in a pre-fertilization capacity, and we estimate that it could prevent ovulation in only 15 percent or less of cases. The drug has no ability to alter sperm function and limited ability to suppress ovulation. Further, data suggest that when administered preovulation, it may have a post-fertilization MOA.

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Section: Introductionsupporting

confidence: 91%

Does Levonorgestrel Emergency Contraceptive have a Post-Fertilization Effect? A Review of its Mechanism of Action

Peck

Rella²,

Tudela

et al. 2016

Linacre Q

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“…The currently available ECs are mostly steroid based and therefore not devoid of steroidogenic side effects (Kahlenborn et al 2002, Ahrendt et al 2010. Puerarin may be projected as a prospective contraceptive molecule that can be further explored for the development of non-steroidal emergency/post-coital contraceptive.…”

Section: Discussionmentioning

confidence: 99%

“…The proposed mechanism of ECs may include prevention of ovulation, attenuation of gamete transport and, most likely, blockage of implantation (Kahlenborn et al 2002). Implantation is a crucial step in the process of establishment of pregnancy, and in rats and mice, it involves participation of oestrogens to a significant extent (Psychoyos 1973).…”

Section: Introductionmentioning

confidence: 99%

Puerarin, a selective oestrogen receptor modulator, disrupts pregnancy in rats at pre-implantation stage

Saha¹,

Saraswat²,

Chakraborty³

et al. 2012

Reproduction

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The tubers of Pueraria tuberosa have folkloric repute as emmenagogue. The n-BuOH fraction of the ethanolic extract of tubers exhibits significant antifertility activity in laboratory animals. The present investigation explored the active principle(s) of the tuber extract with reference to contragestive effects in rats and probed the possible mechanism of action. Bioactivity-guided fractionation identified puerarin as the major constituent that exerted pregnancy-terminating effects. Oral administration of puerarin at R300 mg/kg per day for days (D) 1-2 post-coitus resulted in complete implantation failure. Serum oestradiol levels during D2-D5 and progesterone (P 4 ) level on D5 remained unaffected, but the endometrial expression of oestrogen receptor a (ERa) and ERb was adversely modulated that disrupted the implantation-specific characteristic endometrial oestrogenic milieu. The eventual consequence was loss of endometrial receptivity characterised by down-regulation of the uterine expression of P 4 receptor (PR) and attenuation of endometrial expression of leukaemia inhibitory factor, vascular endothelial growth factor and cyclo-oxygenase-2, the three important signalling molecules involved in the process of implantation. Light microscopic examination of the embryos demonstrated no untoward effect of puerarin on the development of embryos until D4, but D5 blastocysts underwent gross morphological distortion. The findings taken together are interpreted to suggest that puerarin adversely impacts the uterine expression of ER and PR that disrupts the implantation-conducive uterine milieu and prevents implantation. In conclusion, puerarin may be envisaged as a prospective molecule that merits further exploration for the development of non-steroidal post-coital contraceptive for women.

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“…Some studies have suggested histologic or biochemical alterations in the endometrium after emergency-contraception treatment, leading to the suggestion that the pills may act by impairing endometrial receptivity to the implantation of a fertilized egg. 16,41,[47][48][49][50][51] However, other studies have demonstrated little to no effect on the endometrium and raise the question of whether the endometrial changes observed would be sufficient to inhibit implantation. 38,39,42,43,52,53 Other suggested mechanisms, including alteration of sperm or egg transport, interference with the fertilization process, and/or cervical mucus changes, have not been verified by clinical data.…”

Section: Mechanisms Of Action Of Emergency Contraceptionmentioning

confidence: 99%

Emergency Contraception

2005

Pediatrics

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Teen birth rates in the United States have declined during the last decade but remain much higher than rates in other developed countries. Reduction of unintended pregnancy during adolescence and the associated negative consequences of early pregnancy and early childbearing remain public health concerns. Emergency contraception has the potential to significantly reduce teen-pregnancy rates. This policy statement provides pediatricians with a review of emergency contraception, including a definition of emergency contraception, formulations and potential adverse effects, efficacy and mechanisms of action, typical use, and safety issues, including contraindications. This review includes teens' and young adults' reported knowledge and attitudes about hormonal emergency contraception and issues of access and availability. The American Academy of Pediatrics, as well as other professional organizations, supports over-the-counter availability of emergency contraception. In previous publications, the American Academy of Pediatrics has addressed the issues of adolescent pregnancy and other methods of contraception.

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Postfertilization Effect of Hormonal Emergency Contraception

Cited by 39 publications

References 43 publications

Does Levonorgestrel Emergency Contraceptive have a Post-Fertilization Effect? A Review of its Mechanism of Action

Does Levonorgestrel Emergency Contraceptive have a Post-Fertilization Effect? A Review of its Mechanism of Action

Puerarin, a selective oestrogen receptor modulator, disrupts pregnancy in rats at pre-implantation stage

Emergency Contraception

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