Intrauterine Devices

By Melanie McGrath

Intrauterine devices (IUD) are small T- shaped contraceptive devices made of flexible plastic. IUDs are available by prescription only. It is a small object that is inserted through the cervix and placed in the uterus to prevent pregnancy. A small string hangs down for the IUD into the upper part of the vagina. The IUD is not noticeable during intercourse. They work by changing the lining of the uterus and fallopian tubes affecting the movements of eggs and sperm and so that fertilization does not occur. Two types are now available in the U.S. ParaGard and Mirena. ParaGard, which contains copper and can be left in place for twelve years. Mirena, continuously releases a small amount of the hormone progestin, and it effective for five years[i].

Getting an IUD involves a clinic visit. To prevent infection, clinics require women to have check-ups prior to insertion. An IUD is usually inserted during a menstrual period when the cervix is slightly open and pregnancy is least likely. The procedure for insertion takes about five to fifteen minutes. Most women feel cramping during and after insertion[ii].

The IUD is a highly effective method of birth control. When using Mirena about 1 per 1,000 women becomes pregnant. Over five years of use, only about 7 women per 1,000 become pregnant. When using Paragard about 6 per 1,000 women become pregnant. Over ten years of use, about 20 to 30 women per 1,000 become pregnant. Most pregnancies that occur with IUD use happen because the IUD is pushed out of the uterus unnoticed. IUDs are most likely to come out in the first few months of IUD use, after being inserted just after childbirth, or in women who have not had a baby[iii].

Advantages of IUDs include cost-effectiveness over time, ease of use, lower risk of ectopic pregnancy, and no interruption of foreplay or intercourse. Also, Mirena reduces heavy menstrual bleeding by an average of ninety percent after the first few months of use, improves irregular menstrual bleeding after three to four months, reduces menstrual bleeding and cramps and eventually causes menstrual periods to stop all together. Also it may prevent endometrial hyperplasia, which is abnormal thickening of the uterine lining. It may decrease the risk of pelvic inflammatory disease and effectively relieve endometriosis and is less likely to cause side effects than high dose progestin[iv].

Disadvantages of IUDs include the high cost of insertion, no protection against Sexually Transmitted Diseases and the need to be removed by a health professional. In 1 out of every 1,000 women, the IUD will get stuck in or puncture the uterus. Although perforation is rare, it almost always occurs during insertion. About 2% to 10% of IUDs are pushed out from the uterus into the vagina during the first year. This usually happens in the first few months of use. Mirena may cause noncancerous growths called ovarian cysts, which usually go away on their own. Also it can cause hormonal side effects similar to those caused by oral contraception, such as breast tenderness, mood swings, headaches, and acne[v].

The IUD is not recommended for women who aren’t in monogamous relationships, meaning only get an IUD if both you and your partner are completely loyal to each other. The string of an IUD is an open door for bacteria to get into the uterus leading to infections. Also, because women with diabetes are already as a higher risk of infection, most should not use an IUD. Concerns over infection risk have made some clinicians reluctant to use IUDs in patients with any class of diabetes. Some fear that potential increased risk of pelvic inflammatory disease could lead to serious diabetic complications, such as ketoacidosis, which is a condition in which the body has dangerously high levels of acids in the blood[vi].

Sources:
[I] Planned Parenthood (2005) “Intrauterine Devices” http://www.plannedparenthood.org/birth-control-pregnancy/birth-control/intrauterine-devices.htm

[ii] Birth Control Comparison (2007) “IUDs” http://www.birth-control-comparison.info/iudinfo.htm

[iii] Epigee Women’s Health (2008) “Intrauterine Device” http://www.epigee.org/guide/iud.html

[iv] WebMd (2006) “Intrauterine device for birth control” http://www.webmd.com/sex/birth-control/intrauterine-device-iud-for-birth-control

[v] Ibid

[vi] L. MacKay, A. Glasier, JA McKnight (2005) "Contraception for Women with Diabetes mellitus," Practical Diabetes International 22(2): 49-52.