- Women of childbearing potential have to use a highly effective method of birth control (according CPMP/ICH/286/95 Note 3) during the duration of the study. A highly effective method of birth control is defined as those which result in a low failure rate (i.e. less than 1% per year) when used consistently and correctly such as implants, injectables, combined oral contraceptives, some IUDs, sexual abstinence or vasectomised partner.