Many of the women surveyed said that they didn't know that IUDs are more effective contraceptives than the birth control pill and that the devices didn't raise the risk of getting a sexually transmitted disease (STD), the New York Daily News reported.
IUDs, which are small plastic or copper-and-plastic objects inserted into the uterus, are more than 99 percent effective at preventing pregnancy and can be left implanted for years.
In contrast, the birth control pill has been found to be about 95 percent effective.
Lead author Dr. Lisa Callegari, a clinical assistant professor at the University of Washington, said that earlier studies have highlighted some of the mistaken beliefs women have about IUDs, and she and her colleagues wanted to get a better sense of how common they are among average women visiting primary care clinics.
For their experiments, they surveyed more than 1,600 women between the ages of 18 and 50 who had visited one of four clinics in Pennsylvania.
Five percent of the women currently used an IUD, and another 5.8 percent had used one previously.
One in five women correctly stated that the devices are more effective at preventing pregnancy than the pill.
The women in the study were considerably more knowledgeable about the risk of disease related to an IUD, with 57 percent knowing that there is no greater risk of contracting a sexually transmitted disease with an IUD compared to the Pill.
A recent survey of physicians had found that 30 percent of them had outdated ideas about IUDs, including thinking that they are unsafe for women who had never had a baby or being unsure about their safety.