Here are some Medical Abstracts reposted from an email sent to the DFLA yahoo group regarding the lack of evidence that the Morning After Pill will cause an abortion after fertilization (their evidence says that it won't).
Anyways, this does not change my unwavering opposition to birth control, but, it does show that abortion is not committed as much as some pro-lifers care to admit.
An open mind reading and digesting all facts and evidence makes our pro-life argument that much stronger.
_______________________________________________________
From: Je
Date: Thu Jun 16, 2005 2:09 pm
Subject: Morning-After Pill studies
Here are the abstracts for the studies I referred to which suggest that the morning-after pill (or at least, levonorgestrel) does not have an abortifacient effect.
Contraception. 2003 May;67(5):415-9.
Postcoital treatment with levonorgestrel does not disrupt postfertilization events in the rat.
Muller AL, Llados CM, Croxatto HB. Pontificia Universidad Catolica de Chile, Facultad de Ciencias Biologicas, Unidad de Reproduccion y Desarrollo, Av. Alameda Bernardo O'Higgins 340, Santiago, Chile.
Levonorgestrel (LNG), a progestin widely used for regular hormonal contraception, is also used for emergency contraception (EC) to prevent pregnancy after unprotected intercourse. However, its mode of action in EC is only partially understood. One unresolved question is whether or not EC prevents pregnancy by interfering with post fertilization events. Here, we report the effects of acute treatment with LNG upon ovulation, fertilization and implantation in the rat. LNG inhibited ovulation totally or partially, depending on the timing of treatment and/or total dose administered, whereas it had no effect on fertilization or implantation when it was administered shortly before or after mating, or before implantation. It is concluded that acute postcoital administration of LNG at doses several-fold higher than those used for EC in women, which are able to inhibit ovulation, had no postfertilization effect that impairs fertility in the rat.
Hum Reprod. 2004 Jun;19(6):1352-6. Epub 2004 Apr 22.
Post-coital administration of levonorgestrel does not interfere with post-fertilization events in the new-world monkey Cebus apella.
Ortiz ME, Ortiz RE, Fuentes MA, Parraguez VH, Croxatto HB.Unit of Reproductive Biology and Development, Faculty of Biological Sciences, Catholic University of Chile, Chile. mortiz@...
BACKGROUND: Experimental evidence to disprove the belief that emergency contraception with levonorgestrel (LNG) prevents pregnancy by interfering with post-fertilization events is lacking. Here we determined the effect of post-coital and pre-ovulatory administration of LNG on fertility and ovulation, respectively, in the Cebus monkey. METHODS: To determine the effect on fertility, LNG 0.75 mg or vehicle were administered orally or s.c. once or twice within the first 24 h after mating occurring very close to the time of ovulation. Females that became pregnant were aborted with mifepristone and re-entered the study after aresting cycle until each of 12 females had contributed, in a randomized order, two LNG and two vehicle-treated cycles. To determine the effect on ovulation, LNG 0.75 mg or vehicle were injected twice coinciding with follicles smaller or larger than 5 mm in diameter. Six females contributed five treated cycles each.
RESULTS: The pregnancy rate was identical in vehicle- and LNG-treated cycles. LNG inhibited or delayed ovulation only when treatment coincided with a follicle <5 mm diameter.
CONCLUSION: In Cebus monkeys, LNG can inhibit or delay ovulation but, once fertilization has taken place, it cannot prevent the establishment of pregnancy. These findings do not support the hypothesis that emergency contraception with LNG prevents pregnancy by interfering with post-fertilization events.
Contraception. 2004 Dec;70(6):442-50.
Pituitary-ovarian function following the standard levonorgestrel emergency contraceptive dose or a single 0.75-mg dose given on the days preceding ovulation.
Croxatto HB, Brache V, Pavez M, Cochon L, Forcelledo ML, Alvarez F,Massai R, Faundes A, Salvatierra AM.
Instituto Chileno de Medicina Reproductiva, J. V. Lastarria 29, Department 101, Santiago, Chile. hbcroxatto@...
We assessed to what extent the standard dose of levonorgestrel (LNG),used for emergency contraception, or a single dose (half dose), given in the follicular phase, affects the ovulatory process during the ensuing 5-day period. Fifty-eight women were divided into three groups according to timing of treatment. Each woman contributed with three treatment cycles separated by resting cycles. All received placebo in one cycle, and standard or single dose in two other cycles, in a randomized order. The diameter of the dominant follicle determined the time of treatment. Each woman had the same diameter assigned for all her treatments. Diameters were grouped into 33 categories: 12-14, 15-17 or 18-20 mm. Follicular rupture failed to occur during the 5-day period in 44%, 50% and 36% ofcycles with the standard, half dose and placebo, respectively. Ovulatory dysfunction, characterized by follicular rupture associated with absent, blunted or mistimed gonadotropin surge, occurred in 35%, 36% and 5% of standard, single dose or placebo cycles, respectively.
In conclusion, LNG can disrupt the ovulatory process in 93% of cycles treated when the diameter of the dominant follicle is between 12 and 17 mm. It is highly probable that this mode of action fully accounts for the contraceptive efficacy as well as the failure rate of this method. The present data suggest that half the dose may be as effective as the standard dose. (This one isn't a study in itself, but is a literature review which summarizes the results of a number of other studies. I read the review inf ull, and it appears that the abstract is not entirely accurate. It seems to me that mifepristone does have post-fertilization effects, although none are noted for levonorgestrel)
Hum Reprod Update. 2004 Jul-Aug;10(4):341-8.
Mechanisms of action of mifepristone and levonorgestrel when used for emergency contraception.
Gemzell-Danielsson K, Marions L.Department of Woman and Child Health, Division of Obstetrics andGynecology, Karolinska Hospital/Institute, S-171 76 Stockholm, Sweden.kristina.gemzell@...
An emergency contraceptive method is used after coitus but before pregnancy occurs. The use of emergency contraception is largely under-utilized worldwide. One of the main barriers to widespread use is concern about the mechanism of action. Recently, treatment with either 10 mg mifepristone or 1.5 mg of levonorgestrel has emerged as the most effective hormonal method for emergency contraception with very low side-effects. However, the knowledge of the mechanism of action of mifepristone and levonorgestrel in humans, when used for contraceptive purposes and especially for emergency contraception, remains incomplete. The objective of this review is to summarize available data on the effects of mifepristone and levonorgestrel on female reproductive functions relevant to the emergency use of the compounds. When summarized, available data from studies in humans indicate that the contraceptive effects of both levonorgestrel and mifepristone, when used in single low doses for emergency contraception, involve either blockade or delay of ovulation, due to either prevention or delay of the LH surge, rather than to inhibition of implantation.
Anyways, this does not change my unwavering opposition to birth control, but, it does show that abortion is not committed as much as some pro-lifers care to admit.
An open mind reading and digesting all facts and evidence makes our pro-life argument that much stronger.
_______________________________________________________
From: Je
Date: Thu Jun 16, 2005 2:09 pm
Subject: Morning-After Pill studies
Here are the abstracts for the studies I referred to which suggest that the morning-after pill (or at least, levonorgestrel) does not have an abortifacient effect.
Contraception. 2003 May;67(5):415-9.
Postcoital treatment with levonorgestrel does not disrupt postfertilization events in the rat.
Muller AL, Llados CM, Croxatto HB. Pontificia Universidad Catolica de Chile, Facultad de Ciencias Biologicas, Unidad de Reproduccion y Desarrollo, Av. Alameda Bernardo O'Higgins 340, Santiago, Chile.
Levonorgestrel (LNG), a progestin widely used for regular hormonal contraception, is also used for emergency contraception (EC) to prevent pregnancy after unprotected intercourse. However, its mode of action in EC is only partially understood. One unresolved question is whether or not EC prevents pregnancy by interfering with post fertilization events. Here, we report the effects of acute treatment with LNG upon ovulation, fertilization and implantation in the rat. LNG inhibited ovulation totally or partially, depending on the timing of treatment and/or total dose administered, whereas it had no effect on fertilization or implantation when it was administered shortly before or after mating, or before implantation. It is concluded that acute postcoital administration of LNG at doses several-fold higher than those used for EC in women, which are able to inhibit ovulation, had no postfertilization effect that impairs fertility in the rat.
Hum Reprod. 2004 Jun;19(6):1352-6. Epub 2004 Apr 22.
Post-coital administration of levonorgestrel does not interfere with post-fertilization events in the new-world monkey Cebus apella.
Ortiz ME, Ortiz RE, Fuentes MA, Parraguez VH, Croxatto HB.Unit of Reproductive Biology and Development, Faculty of Biological Sciences, Catholic University of Chile, Chile. mortiz@...
BACKGROUND: Experimental evidence to disprove the belief that emergency contraception with levonorgestrel (LNG) prevents pregnancy by interfering with post-fertilization events is lacking. Here we determined the effect of post-coital and pre-ovulatory administration of LNG on fertility and ovulation, respectively, in the Cebus monkey. METHODS: To determine the effect on fertility, LNG 0.75 mg or vehicle were administered orally or s.c. once or twice within the first 24 h after mating occurring very close to the time of ovulation. Females that became pregnant were aborted with mifepristone and re-entered the study after aresting cycle until each of 12 females had contributed, in a randomized order, two LNG and two vehicle-treated cycles. To determine the effect on ovulation, LNG 0.75 mg or vehicle were injected twice coinciding with follicles smaller or larger than 5 mm in diameter. Six females contributed five treated cycles each.
RESULTS: The pregnancy rate was identical in vehicle- and LNG-treated cycles. LNG inhibited or delayed ovulation only when treatment coincided with a follicle <5 mm diameter.
CONCLUSION: In Cebus monkeys, LNG can inhibit or delay ovulation but, once fertilization has taken place, it cannot prevent the establishment of pregnancy. These findings do not support the hypothesis that emergency contraception with LNG prevents pregnancy by interfering with post-fertilization events.
Contraception. 2004 Dec;70(6):442-50.
Pituitary-ovarian function following the standard levonorgestrel emergency contraceptive dose or a single 0.75-mg dose given on the days preceding ovulation.
Croxatto HB, Brache V, Pavez M, Cochon L, Forcelledo ML, Alvarez F,Massai R, Faundes A, Salvatierra AM.
Instituto Chileno de Medicina Reproductiva, J. V. Lastarria 29, Department 101, Santiago, Chile. hbcroxatto@...
We assessed to what extent the standard dose of levonorgestrel (LNG),used for emergency contraception, or a single dose (half dose), given in the follicular phase, affects the ovulatory process during the ensuing 5-day period. Fifty-eight women were divided into three groups according to timing of treatment. Each woman contributed with three treatment cycles separated by resting cycles. All received placebo in one cycle, and standard or single dose in two other cycles, in a randomized order. The diameter of the dominant follicle determined the time of treatment. Each woman had the same diameter assigned for all her treatments. Diameters were grouped into 33 categories: 12-14, 15-17 or 18-20 mm. Follicular rupture failed to occur during the 5-day period in 44%, 50% and 36% ofcycles with the standard, half dose and placebo, respectively. Ovulatory dysfunction, characterized by follicular rupture associated with absent, blunted or mistimed gonadotropin surge, occurred in 35%, 36% and 5% of standard, single dose or placebo cycles, respectively.
In conclusion, LNG can disrupt the ovulatory process in 93% of cycles treated when the diameter of the dominant follicle is between 12 and 17 mm. It is highly probable that this mode of action fully accounts for the contraceptive efficacy as well as the failure rate of this method. The present data suggest that half the dose may be as effective as the standard dose. (This one isn't a study in itself, but is a literature review which summarizes the results of a number of other studies. I read the review inf ull, and it appears that the abstract is not entirely accurate. It seems to me that mifepristone does have post-fertilization effects, although none are noted for levonorgestrel)
Hum Reprod Update. 2004 Jul-Aug;10(4):341-8.
Mechanisms of action of mifepristone and levonorgestrel when used for emergency contraception.
Gemzell-Danielsson K, Marions L.Department of Woman and Child Health, Division of Obstetrics andGynecology, Karolinska Hospital/Institute, S-171 76 Stockholm, Sweden.kristina.gemzell@...
An emergency contraceptive method is used after coitus but before pregnancy occurs. The use of emergency contraception is largely under-utilized worldwide. One of the main barriers to widespread use is concern about the mechanism of action. Recently, treatment with either 10 mg mifepristone or 1.5 mg of levonorgestrel has emerged as the most effective hormonal method for emergency contraception with very low side-effects. However, the knowledge of the mechanism of action of mifepristone and levonorgestrel in humans, when used for contraceptive purposes and especially for emergency contraception, remains incomplete. The objective of this review is to summarize available data on the effects of mifepristone and levonorgestrel on female reproductive functions relevant to the emergency use of the compounds. When summarized, available data from studies in humans indicate that the contraceptive effects of both levonorgestrel and mifepristone, when used in single low doses for emergency contraception, involve either blockade or delay of ovulation, due to either prevention or delay of the LH surge, rather than to inhibition of implantation.
posted by Mark at 9:18 AM
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