IUDs, Implants Most Effective Birth Control (audio) Washington University School of Medicine Share Print E-Mail Loading audio... Caption A study to evaluate birth control methods has found dramatic differences in their effectiveness. Women who used birth control pills, the patch or vaginal ring were 20 times more likely to have an unintended pregnancy than those who used longer-acting forms such as an intrauterine device (IUD) or implant. Results of the study, by researchers at Washington University School of Medicine in St. Louis, are reported May 24 in the New England Journal of Medicine. Credit Jim Dryden Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.