- Pregnancy or breastfeeding. Women of childbearing potential (WOCBP) must practice acceptable methods of birth control to prevent pregnancy. Prior to study enrollment, WOCBP must be advised of the importance of avoiding pregnancy during trial participation and the potential risk factors for an unintentional pregnancy. In addition, men enrolled on this study should understand the risks to any sexual partner of childbearing potential and should practice an effective method of birth control.