Posted on 09/02/2006 1:05:05 AM PDT by hocndoc
I'm convinced that Plan B does not block implantation. Because I keep getting emails, hearing radio personalities and reading posts on various forums claiming that Plan B is an abortifacient, here's a review of information on the medical effects of the pills and on the other effects and lack of effects.
The overwhelming evidence - from several different groups of researchers - is that Plan B, the single ingredient protocol containing a synthetic progesterone called levonorgestrel, only works - when it works - the 5 days or so before and just after ovulation. Furthermore, since few women really know when they ovulate, and only slightly more women will even use the protocol when they have the pills in their medicine cabinet, easy access doesn't change anything.
The best and most ethical research evidence, "On the Mechanisms of short term levonorgestrel administration as emergency contraception" is available online free of charge at this site.
If, as I believe, the pills only work in preventing fertilization, they are only medically justified/necessary 5 days before or one or 2 days just after ovulation, the window of fertility. The other 20 days or so of the menstrual cycle, the pills are useless and un-necessary.
The best evidence is that Plan B works to prevent ovulation or to prevent the oocyte (the "egg") from being released from the ovary and passing to the fallopian tube. This is why the pill is best (and only?) functional before ovulation. In nature, the egg only lives about 24 hours and sperm can live from 2 to 5 days. If the egg is not released, is over 24 hours old, if the sperm cannot get to the egg or if they are dead or incapacitated, there can be no fertilization.
The only post-ovulation effect that has been proven that could prevent pregnancy also prevents fertilization. Levonorgestrel causes the mucus in the cervix to be thick (so sperm have a hard time getting to the uterus and then the fallopian tube where the egg is) and by making the sperm unable to penetrate the zona pellucida, the covering and nurturing cells around the oocyte or egg.
Biopsies of the uterus of women who have ovulated in spite of taking Plan B do not show any changes that would prevent implantation of the embryo. The blood flow and lining of the uterus is normal. Support for this lack of abortifacient effect in the uterine lining is the natural increase of progesterone in women after ovulation and the treatment of some infertile women with progesterone around ovulation or around transfer of the embryo in an in vitro fertilization cycle. Levonorgestrel and the other forms of progesterone actually seem to encourage implantation.
The reason I am still wary is the evidence that the "luteal" phase of the cycle - the time from ovulation to the time the woman starts shedding her uterine lining - is shortened in some women. If the lining is shed early, I can't be sure that there could not be a loss of an embryo which is beginning to implant.
Women continue to get pregnant - and have abortions - at about the same rates in England and other countries where Emergency Contraception is available without prescription. Part of the reason is that even when women have the medicine in their homes and have received education, they take the pills only about 20% of the time when they have unprotected sex. This month's Contraception has a reports that only 11% of 706 women (ages 18 to 44 years old, who knew they were part of a study and who were at risk because they did not want to be pregnant but were using other contraceptives incorrectly) used the pills, even though the medicine is available without a prescription in that country.(H. Goulard et al./Contraception 74(2006)208-213)
And while studies have shown that women and girls don't increase risky behavior, the same studies show that there is no decrease in such behavior, either.
I do wonder whether over the counter use in the US will lead to at least a short-term burst of promiscuity and abuse of women and girls, since the studies on access have all included only women and girls who went to clinics and at least received some education (and, as I said, even those women and girls didn't change their risks).
The medicine has never before been available to men in the US, and there has been at least some effort to provide education to women and girls receiving the medicine in Washington, where pharmacists could dispense the meds under certain conditions.
Anecdotal information from pharmacists and doctors in the UK, Jamaica and the Far East indicates that men buy EC at least as often as women and that that it appears that some women and girls are using EC more than once a month.
Here's some links in this blog and other pro-life writers who have come to the same conclusion. Progesterone, infertility and early pregnancy
Plan B not Abortifacient, But Doesn't Change Much
More on British Experience with OTC EC
Plan B Doesn't Change Much (Actual article reproduced - New information on the study that is often quoted to prove that promiscuity doesn't increase - in fact, there's no change at all - But that's even after going to the clinic, etc.)
Jamaica Experience with Plan B, Jamaican Teens Opt for Abortion over EC
Good (Not Prolife) Review of Emergency Contraception
Another physician's Blog and thorough review, at "LTI": There are at least 6 articles reviewing the facts and the scientific literature. These are the first and the sixth in the series.
A non physician who does a lot of research, "Ales Rarus" Mangling, Mishandling, and Misrepresentation of Science in the Plan B Debate (Part II)
Another unquestionably pro-life blog, "Jivin'Jehosaphat"
(No more Olmert! No more Kadima! No more Oslo! )
There's a link to a public posting of that Durand article from Contraception and several pro-life blogs with even more information.
http://bvs.insp.mx/temas/pildora/LarreaECinContraception2001v64p227.pdf
"I am convinced that Plan B does not block implantation."
And yet...
"The reason I am still wary is the evidence that the "luteal" phase of the cycle - the time from ovulation to the time the woman starts shedding her uterine lining - is shortened in some women. If the lining is shed early, I can't be sure that there could not be a loss of an embryo which is beginning to implant."
Distinction without a difference alert.
What do you mean by "right time." There's only a 5 day window when women can get pregnant.
All of this is covered in the review and backed up by the references in the links.
I just want more evidence, from more researchers.
(No more Olmert! No more Kadima! No more Oslo! )
Good job, hocndoc. Thanks for posting this.
Exactly. And there's no evidence that it's an abortifacient, either. So, about 95% of the uses are unnecessary.
http://www.cmda.org/index.cgi?BISKIT=216935661&CONTEXT=art&art=2360#art1
This...
"The reason I am still wary is the evidence that the "luteal" phase of the cycle - the time from ovulation to the time the woman starts shedding her uterine lining - is shortened in some women. If the lining is shed early, I can't be sure that there could not be a loss of an embryo which is beginning to implant."
...admits the possibility that it could be an abortifascient.
See my post #6.
I'm still waiting on more evidence. (If I were a hunter, I wouldn't shoot into the woods just because I see a pair of antlers. I need to be as sure as I can be that I know what I will and what I won't hit with the bullet.)
"If I were a hunter, I wouldn't shoot into the woods just because I see a pair of antlers."
To legalize Plan B while doubt exists is to do just that.
You seem to be right. Plan B is really Plan B and C, or else Plan Nausea for Nothing.
Plan B means that if you take it before ovulation, in the follicular phase, the nasty surge of hormones will prevent or greatly delay ovulation. Plan C is if the woman is within a few days on either side of ovulation (the sperm can take days to find the egg); obviously the shot of too many wrong hormones SHOULD make the uterus inhospitable for any developing embryo. (You may use the abortifacient word here.)
And if the woman consuming the "postprandial pills" has no clue as to her cycle, and was actually several days or more past ovulation, she took them for nothing.
Plan B has been legal for years in the US. It's just never been over the counter before.
I'm fairly sure that the uterine lining is not "hostile"due to Plan B. It doesn't look like the lining is shed early if there's risk of pregnancy. If another decent study confirms Croxatto and Durand, I'll feel better about informed use of the protocol.
But, I'm afraid that the use in the US will find and highlight every possible abuse and adverse effect.
However, everyone should be aware that I predicted dire results from the H2 blockers such as Prilosec and from the antifungals going over the counter. None of those have occures.
It should be an interesting couple of years.
It should be an interesting couple of years.
"Plan B has been legal for years in the US. It's just never been over the counter before."
I think there's a difference between having to get a doctor involved and just walking into WalMart and buying an abortion.
"I'm fairly sure that the uterine lining is not "hostile"due to Plan B. It doesn't look like the lining is shed early if there's risk of pregnancy."
I admit that contrary information has recently been introduced that requires examination. However, the timing is suspicious, so it requires close examination.
Right now, I don't consider the earlier reports that Plan B kills fertilized eggs to be disproved.
Durand's group biopsied the uterine lining and did not find any thinning or other changes in the lining, except that some women had an increase of glycodelin A, which interferes with fertilization and increases implantation.
Take a look at that "LTI" link. Larimore, Kohlenberg and Sanford, in their Archives of Family Medicine article reproduced at polycarp.org,discussed the strength of evidence of post fertilization effects of the various hormonal contraceptives that are taken every day.
In fact, Plan B has not shown any positive implications as an abortifacient:
Post-coital administration of levonorgestrel does not interfere with post-fertilization events in the new-world monkey Cebus apella. Hum Reprod. 2004 Jun;19(6):1352-6.
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