The present invention relates to intravaginal use of 18-methyl-15ß,16ß-methylene-19-nor-20-spirox-4-en-3-ones of the general formula (I), to an intravaginal ring comprising 18-methyl-15ß,16ß-methylene-19-nor-20-spirox-4-en-3-ones of the general formula I and its use in contraception.本發明係關於通式(I)之18-甲基-15ß,16ß-亞甲基-19-降-20-螺氧-4-烯-3-酮之陰道內用途,關於包含通式I之18-甲基-15ß,16ß-亞甲基-19-降-20-螺氧-4-烯-3-酮之陰道內環及其於避孕之用途。