Women who switched from birth control pills to contraceptive rings liked the change more than women who switched from pills to a skin patch, according to a University of Pittsburgh-sponsored study reported in the current issue of Obstetrics and Gynecology.

The combination of hormones is the same in all three products. The ring and patch have been available since 2002. The ring needs to be in place for three weeks at a time; the patch is changed once a week for three weeks in a row. The pill, however, is taken daily.

"The women who used the ring liked it better than their pill. The women liked their patch worse than the pill," said Dr. Mitchell Creinin, professor of obstetrics, gynecology and reproductive sciences at the university's School of Medicine and first author of the study. Dr. Creinin also is director of family planning at Pitt.

"The women who were happy on the pill were even happier on the ring," Dr. Creinin added. "They had less bleeding, less cramping. That was the average of a population."

Conversely, he said, "the number of complaints were far greater with the patch than the ring, and women were more likely to feel worse on the patch than they did on the pill they were on to start with."

Adverse side effects complained of by patch users included longer periods, cramps, nausea, mood swings, skin irritation or problems with the patch falling off. The most common reasons women gave for discontinuing use of the ring were discomfort and more frequent vaginal discharge.

"There was a small percentage who had more bleeding or cramping [on the ring]," Dr. Creinin said, "but you're never going to satisfy everyone. Women even notice when they change from one pill to another."

The study, the first to directly compare a ring and skin patch, evaluated the experiences of 500 women at 10 centers nationwide, 249 of whom were randomly assigned to use the ring for four consecutive menstrual cycles in 2005 and 2006 and 251 assigned to use the patch.

During the study, the U.S. Food and Drug Administration issued a warning regarding estrogen levels in the patch and related risk of blood clots. Study participants assigned to either product received written information; five women who used the patch said at the end of the study the warning influenced their decision to discontinue use.

"It's possible [other users] didn't like it for that reason and didn't tell us," Dr. Creinin said.

"Overall, however, patch users were twice as likely to discontinue using the product by the end of the third cycle and seven times more likely to say they had no wish to continue once the study was over."

The study was funded in part by Organon USA Inc., manufacturer of the NuvaRing vaginal contraceptive, but the money was given as part of an investigative-initiated, nonrestricted grant from the company. Dr. Creinin said.

"It's like giving money to kids. You don't know what they're going to do with it," he said.