An intrauterine device is a small object placed in the uterus to prevent pregnancy. It must be inserted by a health care professional, but once in place it can remain there for months or years. Despite a history filled with accusations and legal actions, intrauterine devices (with certain restrictions) are still a safe and viable means of contraception for many women.

The Dalkon Shield (on the market 1970-1974) looked rather like a beetle, with an “eye” at one end, five little “legs” on each side, and a “tail” made of many filaments twisted together. It came in two sizes, a larger one for women who had given birth and a smaller one for women who had not. The Dalkon Shield quickly headed to the top of the sales charts. In its first year, it accounted for about two thirds of all intrauterine device sales, and by 1974 sales had reached 2.8 million.

In the preceding four years, twelve women who became pregnant while wearing an intrauterine device had died of infections after miscarrying. Ten of these women were using the large Dalkon Shields; the other two had another type of intrauterine device. In early 1974 the FDA advised physicians to remove any intrauterine device immediately if its wearer became pregnant. A few months later the manufacturer suspended sales of the Dalkon Shield altogether.

Because of its shape, the Dalkon Shield was slightly more difficult to insert than some other designs and therefore had a higher failure rate; that is, more women became pregnant while wearing one because the device had been inserted incorrectly. Some of these women carried their pregnancies into the second trimester with the intrauterine device still in place and developed infections, which spread beyond the uterus into the pelvis and resulted in miscarriage. In these cases the Dalkon Shield was at fault. We now know that there is an association between intrauterine device use during pregnancy and pelvic inflammatory disease (pelvic inflammatory disease). Indeed, after physicians began following FDA advice and removing intrauterine devices immediately if women accidentally became pregnant, deaths from septic miscarriages stopped being problematic. However, the reputation of intrauterine devices was sorely damaged, since people confused intrauterine device use in general with the problems associated with pregnancy.

Furthermore, some studies at the time showed that women who used intrauterine devices had a higher risk of pelvic inflammatory disease than women who chose another method of birth control. In thinking about the validity of these studies, remember that this era, the late 1960s and early 1970s, was also the time of the so-called sexual revolution, when gonorrhea was increasing dramatically and chlamydia was introduced into the United States.

Many women, attracted by the long-term contraception made possible by the intrauterine device, abandoned their diaphragms (which protect the cervix) and their spermicides (which kill germs as well as sperm). Women also abandoned birth control pills, which do not prevent infectious organisms from being deposited in the vagina, but do offer some protection against the upward spread of sexually transmitted diseases to the uterus and fallopian tubes. Men abandoned condoms (which prevent infection from reaching the female reproductive tract). Therefore, many women who used intrauterine devices and had intercourse with an infected partner did get sexually transmitted diseases that did migrate upward and did indeed destroy their fertility. But it was not the intrauterine device itself that caused the infection.

The problem with these studies on pelvic inflammatory disease was that the researchers designing them compared women who used intrauterine devices to women who used diaphragms or spermicides or birth control pills or condoms, all of which offer certain kinds of protection. The control group (to whom the women with intrauterine devices were being compared) should have been women using no contraception at all.

In the United States today, three intrauterine devices are available: the Progestasert and the Mirena, which contain progestin (synthetic progesterone), and the ParaGard, also known as the copper-T. Other types of intrauterine devices are available in Canada and Europe, and women sometimes go abroad to have these inserted.

The ParaGard is a T-shaped plastic device about 1.5 inches long and 1 inch wide. The long vertical arm is wrapped with copper wire and the two horizontal arms have copper collars. At the tail end of the T is a bulb through which a piece of polyethylene thread is inserted so that its two ends hang down to help remove the intrauterine device. The ParaGard can remain in place as long as ten years and is impregnated with barium sulfate so that it will show up on x-rays.

The Progestasert and the Mirena are also plastic T-shaped devices of the same size as the ParaGard, with two-threaded tails for removal. Each has a reservoir in the vertical stem of the T, which contains a small amount of progesterone; each uses barium sulfate to make it show up on x-rays. Mirena can remain in place for five years, and Progestasert, an older version, for one year, after which the progesterone is used up.

Figure: Intrauterine devices: A, the ParaGard is wrapped with copper wire; B, the Mirena has a reservoir containing progesterone. It is believed that these devices work by inactivating or killing sperm before they reach the egg

Figure: Intrauterine devices: A, the ParaGard is wrapped with copper wire; B, the Mirena has a reservoir containing progesterone. It is believed that these devices work by inactivating or killing sperm before they reach the egg


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