RESULTS	Tranexamic acid reduced mean menstrual blood loss by 45 % , from 175 ml to 97 ml ( 95 % CI for the difference in menstrual blood loss 52 to 108 , P < 0.0001 ) , norethisterone increased mean blood loss by 20 % from 173 ml to 208 ml ( 95 % CI for the difference in menstrual blood loss -64 to 2 , P = 0.26 ) .\