- Women of child bearing potential: 1) Must have a negative urine pregnancy test at screening and just prior to study drug insertion, if this takes place on a different day from the screening visit; 2) Agree to use a highly effective method of birth control (defined as a low failure rate of less than 1% per year) as follows: implants, injectables, combined oral contraceptives, sexual abstinence from the date of the subject's last menstruation until completion of the follow-up visit, vasectomised partner or barrier method (condom with spermicide). Women in a same sex relationship do not need to meet this criterion if they confirm that there is no possibility of pregnancy;