<qa>  What is the Pearl-Index?3. commit to continued abstinence from heterosexual intercourse excluding periodic abstinence or the withdrawal method or begin two acceptable methods of birth control with a Pearl-Index 1. without interruption from 4 weeks before starting study drug, throughout study drug therapy and for 12 months after end of study drug therapy, even if she has amenorrhoea. Apart from abstinence, acceptable methods of birth control are: 