((hugs)) Good for you for asking the tough questions! I hate to tell you this, but the main function of EVERY IUD is potentially abortive. They discovered that by putting a peach pit in the uterus of a camel, the camel couldn't get pregnant. By the same token, when an egg is fertilized it won't implant because there is a foreign body in the uterus that 1) tells the body it's already pregnant and 2) tells the body that there is a potential threat to the baby. From Mirena's website, it makes the lining of your uterus thin (this may also result in benefits like less menstrual bleeding over time)
Also, any hormonal form of birth control (pill, shot, patch, IUD) changes the lining of the uterus to prevent a fertilized egg from implantation. The first function is to prevent ovulation but it doesn't always work. In fact, one study showed a possible 50% ovulation rate in women tested positive for pregnancy. Five weeks later they were re-tested and tested negative. So, the ovulation prevention may not work nearly as well as the abortive method. Also, you CAN ovulate even if you are not having periods. This is why it is possible to get pregnant before having your first period post partum. So, you ovulate, you had no period, and then the fertilized egg cannot continue growing into this new person because fetus cannot implant. According to this http://www.fhi.org/en/RH/Pubs/Network/v20_1/NWvol20-1IUDs... site about IUDs "A 1987 study to monitor hCG production in 40 women using IUDs found only one probable fertilized egg among 107 cycles. "Whatever the IUD's specific mechanism of action, it appears that the IUD effectively interrupts the reproductive process before implantation," the study concluded." So....there was AT LEAST one abortion in that study of only 40 women. And how many women are using IUDs? According to Wikipedia on IUDs "The pregnancy rate during IUD use is very low (less than 1% per year). If pregnancy does occur, the IUD should be removed. Although IUDs are not teratogenic,[35] presence of the IUD increases the risk of miscarriage, particularly during the second trimester. "
I'm not comfortable with that statistic, no matter how small. I mean, they tell women not to have a VBAC because of the half to one percent chance they might have a SLIGHT tear in the uterus. Yet there's a same chance of having an abortion with the IUD and yet they don't consider the IUD as abortive?
No, they don't consider these abortive because 1) they don't know for sure how often this happens and 2) simply preventing the baby from implantation may not be considered abortion because most people, doctors included, do not consider it a baby at that point. When is the point that it suddenly becomes a person? Well that's up for wide debate, but many sadly believe it is not until it takes it's first breath.
Probably the 'safest' form of BC is the barrier method. The cervical cup can be used prior to sex so there's no stopping in the heat of the moment. NFP works well for many people I have spoken with, but I got pregnant 4 times. Long story, but most don't seem to have such a problem as I did.
You aren't SURE you are sworn off more babies so doing something permanent isn't a great idea as I'm sure you guessed. You might also be interested in reading Quiverfull. Some, like myself, begin to study what God thinks about children and decide that ALL forms of birth control is not "God's best."
Feel free to PM me. I wish you all the best and am praying for you today that God heals your endomitriosis!