Birth Control

Ok.  Typing that out just is weird.  Birth.  Control.  Controlling birth?  Can I get a prescription for a Life Control pill :)
Nevertheless, family planning is important to my husband and I.  When I brought up the idea of an IUD to my mom she presented an interesting question about how it works.  Why is that important?  Because the timing of the prevention might make all the difference in whether or not we are sinning.  But that also is a gray matter.  Take for instance this article (I paged through quite a few and wow there's a lot of junk out on the internet these days):  http://www.godweb.org/stemcell.htm  The author explains, "The relatively modern idea that life begins at conception is entirely unbiblical. Not only that, it is more in accord with a purely humanistic perspective for it places the initiative for life in the hands of the human parents."  And I suppose that ties RIGHT in with my sassy comment at the top.
Ugh.
I HAVE been having heartburn over this matter for some years now.  I never did anything about it when I was on the pill because it was just easy to push the questions out of my mind.

How the pill I've taken works (from the mfg website)
The two types of Pill work slightly differently to prevent pregnancy. With the Combination Pill, the estrogen prevents pregnancy by stopping the development of the egg in the ovary. The progestin component may prevent the egg from being released by the ovary in about one-half of users, and thickens the mucus in the cervix to help prevent sperm from reaching the egg. Progestin may also slow the movement of the egg through the fallopian tubes. The POP relies fully on the activity of progestin to prevent pregnancy.
Both the Combination Pill and the POP may also prevent fertilized eggs from implanting in the uterus (womb).

How the IUD I am thinking of getting works (from the mfg website)
The levonorgestrel-releasing intrauterine system slowly releases very small amounts of the hormone levonorgestrel directly into your uterus.
There is no single explanation for how a hormone IUD works. It may:
-Thicken cervical mucus to prevent sperm from entering your uterus
-Inhibit sperm from reaching or fertilizing your egg
-Make the lining of your uterus thin
It may stop the release of your egg from your ovary, but this is not the way it works in most cases. Most likely the above actions work together to prevent pregnancy. Like other forms of birth control, this method is not 100% effective.

First of all ~Let me express my frustration that they don't know exactly how these all work.  Wow!  I mean, I understand that all bodies are different but it's crazy to me that they don't have a narrowed down explanation for what they put in people's bodies?!  I suppose.  Perhaps that's an argument for natural family planning?

The vague explanation I think my mom was remembering when she heard I was considering an IUD (from the mfg website) with concerns that the body was trying to rid itself of a foreign object thereby aborting a possibly fertilized egg.  Can I just comment that this "explanation" is the very mostest ridiculous?  I was interested at first because I would really love to be drug/hormone free but I don't suppose I can in good conscious consider what even the drug company seems to know nothing about??
Ideas about how copper IUDs work include preventing sperm from reaching the egg and preventing the egg from attaching (implanting) in the uterus.  It does not alter your body's natural menstrual cycle.