How the IUD Works

Both the copper and the progestin in IUDs are effective in preventing fertilization. The ParaGard with copper seems to alter the tubal and uterine fluids, which affects the sperm and egg so fertilization does not occur. Mirena has effects similar to those of hormonal contraceptive methods such as the pill and Depo-Provera. It disrupts ovu­latory patterns, thickens cervical mucus, alters endometrial lining, and impairs tubal motility (G. Stewart, 1998).

At a Glance

How to Use the IUD

The IUD is inserted by a health-care professional using sterile instruments. The inserter and IUD are introduced through the cervical os into the uterus; the inserter is then with­drawn, leaving the IUD in place. The ParaGard can be in place for 12 years, and the progestin IUD Mirena for 5 years (Planned Parenthood Federation of America, 2008). A woman should be screened for gonorrhea and chlamydia before IUD insertion because the procedure can carry bacteria associated with these STIs into the uterus. The use of the IUD is best limited to women who are in monogamous relationships and do not have other risk factors for sexually transmitted infections (Speroff & Fritz, 2005).

While a woman is using an IUD, she or her partner needs to check each month after her menstrual period to see that the thread is the same length as when the device was inserted. To do this, one reaches into the vagina with a finger and finds the cervix. The thread should be felt in the middle of the cervix, protruding out of the small indentation in the center. Occasionally it curls up in the os and cannot be felt, but any time a woman or her partner cannot find it, she needs to check with her health-care specialist. She should also seek attention if the thread seems longer or if the plastic protrudes from the os; this probably means that her body is expelling the IUD.