IUDs do not cause infertility. She called them a good option for women who are in monogamous relationships and thereby run a low risk of sexually transmitted infections. But she said women should consider condom use, choose partners wisely and get tested for chlamydia. Dr. Gerson Weiss, chairman of obstetrics, gynecology and women's health at the University of Medicine and Dentistry of New Jersey in Newark, said he is not ready to clear IUDs. The copper IUD, a T-shaped piece of plastic wrapped in copper wire, slowly releases copper, preventing pregnancy by irritating the uterine lining and altering fluid in the uterus and fallopian tubes.
Some new versions release contraceptive hormones.
IUDs are 99 percent effective and last 10 years. About 4 million Dalkon Shields were sold from 1971 through 1974, when U.S. sales were halted because the design was blamed for painful, sexually transmitted uterine infections resulting in infertility, hysterectomies, ectopic pregnancies and at least 18 deaths. Meanwhile, IUD use fell from nearly 10 percent to about 1 percent of the U.S. contraceptive market today. Yet with 106 million users, IUDs are the world's most prevalent reversible contraception. Hubacher's group studied 1,895 women at three Mexico City public hospitals from 1997 to 1999.