In Latin American countries certain procedures commonly used in obstetrical care (e.g. episiotomy) have been shown to be ineffective or harmful. This study hypothesizes that obstetrical procedures can be changed and new guidelines implemented via peer opinion leader training. It tests an intervention designed to motivate and facilitate health care professionals' development through the implementation and maintenance of simple evidence-based guidelines to increase the use of evidence-based practices by birth attendants at the hospital level in Argentina and Uruguay. The primary outcomes are the use of episiotomies and of oxytocin during the third stage of labor; secondary outcomes include perineal sutures; postpartum hemorrhages; birth attendants' readiness to change status. The sample size was based upon a 10% frequency of oxytocin use and 20% use of episiotomies in the control group. The study hypothesizes a 40% absolute increase in oxytocin use in the intervention group; a 20% absolute reduction in use of episiotomies in the intervention group, calculated at a 0.05 significance level with 80% power.