I was reading that link on Facebook "Do I lose my virginity to the boy I love even though we aren't getting married", something along those lines and you wrote that an IUD does not prevent conception and that it forces a miscarriage so it would be considered an abortive. That is true? Seriously true? How do you know? I was told that the IUD creates a hostile environment within the uterus which makes it nearly impossible for sperm to survive and that is how it prevents pregnancy. That is what the doctor told me when I got Mirena for extremely heavy periods lasting upwards of three months sometimes. I mean birth control isn't a sin if you are using it for medical reasons, right?
Hormonal products, even if they happen to be a birth control, can be used for other purposes and are not a sin by themselves.
The problem when reading medical literature is that definitions are not always the same. In the medical field, a child is not considered conceived until the fertilized egg is implanted in the wall of the uterus. For Christians, conception takes place when a sperm fertilizes an egg.
Mechanism of action
Although the precise mechanism of action is not known, currently available IUCs work primarily by preventing sperm from fertilizing ova. IUCs are not abortifacients: they do not interrupt an implanted pregnancy. Pregnancy is prevented by a combination of the "foreign body effect" of the plastic or metal frame and the specific action of the medication (copper or levonorgestrel) that is released. Exposure to a foreign body causes a sterile inflammatory reaction in the intrauterine environment that is toxic to sperm and ova and impairs implantation. The production of cytotoxic peptides and activation of enzymes lead to inhibition of sperm motility, reduced sperm capacitation and survival, and increased phagocytosis of sperm.… The progestin in the LNg IUC enhances the contraceptive action of the device by thickening cervical mucus, suppressing the endometrium, and impairing sperm function. In addition, ovulation is often impaired as a result of systemic absorption of levonorgestrel.
[Dean, Gillian; Schwarz, Eleanor Bimla (2011). "Intrauterine contraceptives (IUCs)". In Hatcher, Robert A.; Trussell, James; Nelson, Anita L.; Cates, Willard Jr.; Kowal, Deborah; Policar, Michael S. Contraceptive Technology (20th revised ed.). New York: Ardent Media. pp. 147–191. ISBN 978-1-59708-004-0. p.150]
Notice the "they do not interrupt an implanted pregnancy." It is a statement answering the wrong question. Does the IUD prevent implantation of a fertilized egg? If yes, then it is an abortive. Later we find the statement that it does "impairs implantation."
I also found a study that emphasized that no fertilized egg was found in the shed lining of women. That sound significant, but the only time a fertilized egg would be in the shed lining is if it had been implanted.
What Mirena and other combination IUD with hormones is set up a series of defenses against pregnancy. The first is the hormone does interfere with the release of eggs, not as well as birth control pills, but it does slow down the release of eggs. It is this same hormone that is giving you some relief in your heavy bleeding. It prevents the lining from getting thicker to support a fertilized egg. This is the second defense. The third defense is that the hormone interferes with the sperm's motility (their ability to move), capacitation (the shift a sperm goes through in preparation to penetrate an egg), survival (the life span of the sperm cells), and phagocytosis (the ability of the sperm to actually penetrate the egg). Basically the two would reduce the odds that fertilization would occur. How much is not said.
The fourth defense is the IUD itself. It irritates the lining of the uterus and making it harder for a fertilized egg to implant itself in the lining.
The odds of pregnancy is about 0.2% with the hormonal IUD.
It is the possibility that a fertilized egg being aborted that causes me to say that the IUD is not a good choice for Christians. But if you are not having sex, then you don't have to worry about a child being aborted. Too many people are using contraceptives to avoid the consequences of sin, but the lack of pregnancy doesn't make fornication less sinful (Hebrews 13:4).