Intrauterine Device (IUD)

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What is an intrauterine device?

An intrauterine device (IUD) is a birth control device placed in a woman's uterus. This procedure involves local anesthetic and must be done at a doctor's office or clinic. There are several types of IUD's in production, but currently there are only two available in the United States. One type is the hormone-free Copper T (ParaGard), and the other is LNG-IUS (Mirena) which releases a synthetic female hormone. The LNG-IUS is effective for 5 years, and the Copper T remains effective for as long as it is in place — 10 years or more.

How does an IUD work?

The IUD works by multiple mechanisms:

  1. A primary mechanism is currently believed to be the prevention of fertilization. The chemicals in the IUD are thought to change the composition of the natural secretions in the uterus, making it harder for the sperm to reach and fertilize the egg.
  2. The IUD also works by making it harder for an embryo to implant in the uterus.
  3. IUD's do not prevent ovulation. The LNG-IUS releases the synthetic hormone levonorgestrel, which may include mechanisms similar to progestin-only pills. However, even for hormone-treated IUD's, ovulation is not prevented in most cases.

How effective is the IUD?


Annual Failure Rate

Studies show that IUD's have an overall annual failure rate of 3.2%, although this may vary by the type of IUD. That means each year less than 1 in 30 users experience an unplanned pregnancy. IUD's have a lower annual failure rate of 2.7% for married couples, but a higher rate of 6.5% for cohabiting couples. IUD's are also less effective for teens and couples in their early twenties. Compared to other methods, the intrauterine device is a highly effective method of birth control.

Side-effects and health risks of the IUD

There are many potential side-effects and health risks involving IUD. These include irregular bleeding and menstrual cycle changes, cramping and pain, increased risk of PID, spontaneous expulsion (2-10% in the first year), perforation of the uterus, and serious pregnancy complications should a contraceptive failure occur. LNG-IUS may also have some of the same problems associated with progestin-only pills, although currently the effects of the synthetic hormones are touted as a health benefit.

Considerations for Christians

The IUD prevents both fertilization and implantation, but generally does not prevent ovulation. Most medical organizations define pregnancy as beginning with implantation. By this definition the IUD is still considered contraception. However, life begins when fertilization occurs, so many Christians would consider the IUD an unacceptable method of birth control as it poses a risk to pre-born life, i.e. the potential to cause a very early abortion.

Related Links

Source for Failure Rates: N Ranjit, A Bankole, JE Darroch, S Singh, "Contraceptive Failure in the First Two Years of Use: Differences Across Socioeconomic Subgroups," Family Planning Perspectives, 2001, 33(1):19-27. (pdf)


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