Comments on: Plan B; dig deeper

By: Funky Dung

Funky Dung — Thu, 07 Sep 2006 22:11:28 +0000

There’s another post in the series up now. He specifically addresses the claim that Plan B is 75% effective (which would require some post-fertilization effect(s)).

By: Paul

Paul — Wed, 06 Sep 2006 16:39:15 +0000

I'm curious what you think of the posts on LTI Blog specifically addressing whether or not there are post-fertilization effects at all.
I've read those, but they don't provide definite enough reasoning to overcome the central moral problem. The effect of Plan B may turn out to be purely pre-fertilization, but there is nothing currently known that rules out a 10% (or whatever) effect. In which case, it's not moral to use it.

By: Funky Dung

Funky Dung — Tue, 05 Sep 2006 22:53:38 +0000

I’m curious what you think of the posts on LTI Blog specifically addressing whether or not there are post-fertilization effects at all. One of the interesting things that Serge has pointed out is that if ovulation is estimated by simply counting 14 days from menstruation, the number of expected ovulations may be very far off, since 28-day cycles w/ day 14 ovulation are mythical. Any woman who practices NFP, or the attemtive husband thereof, knows this well.

By: Paul

Paul — Tue, 05 Sep 2006 21:34:48 +0000

In reply to Lightwave:

we have to realize we know more about the abortifacent effects (or lack thereof) for Plan B than most other substances on earth.

Based on the studies I’ve read, I think it is hard to say anything either very firmly positive or negative about the abortifacient effects of Plan B.

This means that we have a higher degree of confidence in the saftey of this substance than, say, pennut butter (which has not been studied)

There are far stronger rational grounds for supposing that Plan B is abortifacient than peanut butter.

By: Paul

Paul — Tue, 05 Sep 2006 21:33:33 +0000

In reply to Ales Rarus:

Your post strongly implies that I relied solely on Croxatto for scientific support in this matter.

Your post here relies very heavily on summaries of Croxatto et al's studies, with the most important of those studies (so far as I can see) being the one involving humans. I think that the studies of Croxatto et al have generally been summarized wrongly, inaccurately, or misleadingly (and in fact only weakly and indirectly provide some support for your position), and I concentrated on showing this in the study involving humans. If you think that some of the other studies (perhaps by other authors) do in fact provide good support for your position, then detail the actual studies (not the summaries) and say why. I have found nothing in particular, since the other studies seem to be weaker still than even Croxatto et al.

1. Given the lack of strong evidence indicating that Pan B has abortifacient properties, don't you think some pro-lifers are making the movement look foolish by confidently decrying as an abortion drug?

I welcome accuracy everywhere.

2. You can't prove a negative. The burden of proof is one whoever claims the positive.

There simply aren't any fixed and universal rules for assigning the burden of proof. In the current case, since the issue is one of life and death, caution is necessary. If person A says to me: "I don't have proof, but my medical training suggests to me that the substance you are about to ingest may kill you", and person B replies, "See, he says he has no proof, so go ahead and take it", then I know exactly who it is wise to trust.
Another two points relating to statements made on your blog:

in relation to ovulation, Plan B's method of action is not solely by preventing ovulation (in which case there could be essentially no post-fertilization effect, since fertilization could not occur), but also but by allowing ovulation, but with altered hormone levels which may prevent pregnancy (or so Croxatto et al, claim, but do not demonstrate or measure);
the AAPLOG association, rather than always leave everything up to each member physician to decide, has recently issued a letter to the FDA pointing out an apparent increased risk of ectopic pregnancy with the use of Plan B.

By: Lightwave

Lightwave — Tue, 05 Sep 2006 08:03:03 +0000

I have to say, I’m with funky on this one, Paul. All you’ve done is stated there is no conclusive evidence that something “doesn’t exist”. Indeed there is *almost never* any evidence that something “doesn’t exist”. Instead, we have to say that there is such little evidence that it actually exists, that we have to generally accept that something “doesn’t exist”.
What does this mean? Well, I can’t prove to you that unicorns don’t exist. I can, however, state that there is so little evidence that they do exist that we can generally accept that they don’t exist.
The implications for your article here, are that we are presented with the same type of evidence as the unicorn example. We are left in a case where it is far more reasonable to accept that abortifacent effects do not exist.
Now, some folks will begin to say, “but we should err on the side of caution”. Indeed, having studied the effects, in this case we have to realize we know more about the abortifacent effects (or lack thereof) for Plan B than most other substances on earth. This means that we have a higher degree of confidence in the saftey of this substance than, say, pennut butter (which has not been studied). This results in a reductio ad absurdum, saying to “err on the side of caution” would mean using Plan B frequently, and never eating pennut butter (or any other substance that has not been studied for abortifacent effects). Thus, the “err on ths side of caution” argument just doesn’t hold water.
(By the way, though my argument doen’t further my agenda, for the record I find I sit on the pro-life and conservitive catholic side of the fence.)

By: Funky Dung

Funky Dung — Mon, 04 Sep 2006 19:28:23 +0000

The stated position on Ales Rarus is “Plan B is not abortifacient”. Zero is an extreme position.

“There’s no evidence that Plan B is abortifacient”, “Plan B has not been proven to be abortifacient”, and similar statements are a bit long for a post title. ;)

“I had already looked at the other studies you point at — and more besides”

Then please say so. Your post strongly implies that I relied solely on Croxatto for scientific support in this matter. Your fisk of Croxatto is an interesting read and useful in this debate. However, you’ve written in such a way that your fisk is set up as a rebuttal to my points. Croxatto’s findings are not the only ones cited directly or indirectly on my blog.

In which case, some caution is necessary. I would agree that a statement like: “Plan B is a proven abortifacient” is not supported by current studies, and is not a scientific statement. Conversely, the statement “Plan B is not abortifacient” is also non-scientific.

1. Given the lack of strong evidence indicating that Pan B has abortifacient properties, don’t you think some pro-lifers are making the movement look foolish by confidently decrying as an abortion drug?
2. You can’t prove a negative. The burden of proof is one whoever claims the positive.
3. “Lollipops don’t cause mouth cancer” is an unscientific statement, too, but that doesn’t mean it isn’t wrong.

“So, Ales Rarus (and anyone else pointing to this paper) needs to dig deeper into the science of these issues before making claims, or relying on the claims of others.”

Likewise, 153 needs to digger deeper into the scientific claims on other blogs before assuming that fisking a single study will dismantle the blogger’s entire argument, when in fact he has cited or linked to other who have cited several other studies.

By: Paul

Paul — Sun, 03 Sep 2006 08:16:07 +0000

The stated position on Ales Rarus is “Plan B is not abortifacient”. Zero is an extreme position. And while that number is certainly consistent with the current state of knowledge, other equally consistent larger numbers simply aren’t ruled out.
The paper of Croxatto et al chooses not to address the numerical uncertainties in its conclusions, but a reasonable figure based on what they do provide would suggest that 10-20% of the effect could be post-fertilization, without their study being able to detect this.
I had already looked at the other studies you point at — and more besides — and not found anything much better. For obvious reasons, more precise studies are extremely difficult to do. It may well turn out that zero is the right answer. But nothing currently rules out the post-fertilization effect of Plan B being at the 10-20% level.
In which case, some caution is necessary. I would agree that a statement like: “Plan B is a proven abortifacient” is not supported by current studies, and is not a scientific statement. Conversely, the statement “Plan B is not abortifacient” is also non-scientific.
(I have also looked at the other statements of Croxatto et al as it relates to possible abortifacient properties of Plan B. As far as I can tell, the study was performed so as to help remove a political road-block to providing emergency contraception. Which would help understand why the study seems to be promoted by them as far more definitive than it actually is.)

By: Funky Dung

Funky Dung — Sat, 02 Sep 2006 19:21:32 +0000

The Croxatto paper you mention is not the only one that supports my claim, nor is it the only one cited in the 2005 Population Council press release I linked to. Also, follow the links I’ve given (as an addendum to the post to which you’ve responded) to LTI Blog for more links to papers.