Thursday, September 07, 2006

The Importance (or lack thereof) of Fertilized Eggs

There's a conversation going on in one of my posts below having to do with the so-called "rythym method"/Natural Family Planning and the death of very young embryos.

I linked to the article here: Journal Article. L. Bovens argues that it's quite possible that the rythym method causes quite a bit of fertilized egg death, rivaling other birth control methods, such as condoms or perhaps even the pill.

Putting that article aside for a moment, I will argue as follows -

1) It's widely understood that 50% of pregnancies end in miscarriage, most of them prior to the woman even knowing she's pregnant.
2) The earlier in the pregnancy, the more likely the miscarriage will happen, so most of the 50% number is at the zygote (cluster of eggs) stage
3) An egg fertilized in optimum conditions (i.e. sperm not too old or egg not too long after release) has a better chance of surviving than one fertilized a few hours/days "too early" or "too late"
4) An egg fertilized in less than optimum conditions is a likely cause of the high numbers of early miscarriage.
5) Natural family planning has resulted in many pregnancies (much more so than birth control pills), so we know that eggs are getting fertilized with this method.

Therefore, Natural family planning is an intentional limiting of sexual activity to times when an egg, if fertilized, would less likely survive. And, since natural family planning does end up fertilizing a lot of eggs, it is also probably killing a lot of zygotes.

The question I have for Amy is this: Which one of the 5 premises do you think is wrong and why?

Aside from this, I would argue that the intention of using condoms and other barrier methods is to prevent fertilization from ever occurring, so the intention is essentially that there would never be any risk of zygote death. In fact, the true moral high groud in this matter would go to those who are sterilized. Thus, sterilization, condoms, or diaphrams should be the preferred methods of birth control for those who are truly concerned about zygote death. When a couple is ready to have children, they should at least make a passing attempt to time their intercourse during ovulation.

In truth, I suspect that very few people are really concerned about zygote death, since no one seems to be trying very hard to prevent it in any meaningful way. One could argue that not directly trying to cause their death makes the difference, but we certainly try to prevent later miscarriages, and things like SIDS.


Blogger A Pregnant Mind said...

I'm willing to continue discussing this issue in a second (set of) posts/comments, but first I feel the need to return to (what I understood to be) the original issue, and that was about the /implantation/ of fertilized embryos.

If we return to that topic (which I think was the main thing I addressed in my first comment to your original post-- sorry, I don't know how to link in comments) I'd have to stand by my statement:
"If the body on its own is unable to *receive* a fertilized egg, it is a fertility/health issue and not the result of choices in timing." (emphasis added).

Failing to implant is a problem with the endometrium (uterine lining). Since it is designed to be "receptive," its /not/ being receptive indicates a problem.

1:45 PM, September 08, 2006  
Blogger A Pregnant Mind said...

The hormonal pattern works this way:
Estrogen (among other hormones present before ovulation) rebuilds and begins prepping the uterine lining. After ovulation, estrogen drops dramatically and progesterone becomes the dominant hormone. This progesterone is produced by the /corpus luteum/, which is sort-of the shell of the egg that was just released and is now available for fertilization.

One function of the progesterone is to complete the process of making the endometrium ready/receptive, once the egg is available. The progesterone from the /corpus luteum/ then sustains the uterine lining until a zygote would have a chance to implant and start sending little "I'm here! Take care if me!" signals (HCG) to prevent the lining from sloughing (menses).

If there is a breakdown of this system (e.g., some women's luteal phases-- life-span of the /corpus luteum/-- are too short, not sustaining the lining long enough), when the /corpus luteum/ finishes breaking down, progesterone levels plummet, allowing the uterine lining to slough off into another menstruation.

1:46 PM, September 08, 2006  
Blogger A Pregnant Mind said...

All that to say that the timing of intercourse has nothing to do with whether or not the embryo implants.

I can talk some more about your other points next time if you still want me to.

1:47 PM, September 08, 2006  
Blogger Barbara Preuninger said...

OK, I finally understand what you're saying, Amy. The timing of conception should have no particular affect on the likelihood of implantation. Because it is not conception that affects the conditions of the uterus, but the woman's hormonal cycle (at least until the implantation actually occurs).

Did I understand you correctly?

3:52 PM, September 08, 2006  
Blogger A Pregnant Mind said...

You got it ;)

4:38 PM, September 08, 2006  
Blogger Barbara Preuninger said...

Thanks for your detailed explanation (and patience!). I would still like to hear what more you have to say.

10:06 PM, September 09, 2006  
Blogger A Pregnant Mind said...

I'm thankful that it's a want-to-understand discussion rther than want-to-create-conflict type. The latter make my teeth hurt.

To refer to your last topic, I would say that's where my view differs from the Catholic view. Their offical syance is that anything "unnatural" (not working with the body) is unacceptable.

This includes both pills and barrier methods. I can understand the objections, but only "buy into" the objections to hormanal methods.

Like you say, barrier methods work exclusively in a contraceptive way, and b/c of that are a desirable method for certain people.

4:49 PM, September 11, 2006  
Blogger A Pregnant Mind said...

I don't outright reject any of your five assumptions, but mostly for the same reason that I really don't buy into them either.

To use #1 as an example,I've heard that too, but I've also never actually seen research that confirms it (even Bovens, writing in defense of his/her article, offers two different studies that don't match the 50% s/he put forward earlier).

Depending on what you *want* to think you are going to put more or less emphasis on certain theories. The reality is the answer(s) to these questions aren't likely to change anybody's mind, so (this is my theory) it's unlikely any real studies will be done.

One example of this is that no one knows how many ovulations happen while women are on the pill. We only know how many pgs there are. So we don't have a way to know which mechanism of of hormonal contraception is doing the most work.

Pro-lifers on the pill are probably the only ones "knowing" would affect, and (many of them not knowing an effective alternative exists, or not wanting the work involved) would rather not know for sure.

There is a certain measure of security in saying, "You can't prove that."

5:17 PM, September 11, 2006  

Post a Comment

<< Home