在多中心试验中,对使用释放左旋18甲基炔诺酮(levonergestrel)和雌二醇(estradiol)的阴道避孕环(C.V.R)者与用复方避孕药Nordette者,进行了比较性研究。阴道避孕环的外径为50和58mm,分别每天释放250和290μg左旋18甲基炔诺酮和150及180μg雌二醇。这些阴道避孕环的用法是:连用三周,然后取出一周。阴道避孕环和口服Nor- In a multicenter trial, a comparative study with Nordette, a compound contraceptive, was performed on vaginal contraceptive rings (C.V.R) using levonorgestrel and estradiol. The external diameter of the vaginal ring was 50 and 58 mm, releasing 250 and 290 μg of L-18 norethindrone and 150 and 180 μg of estradiol daily. The use of these vaginal rings is: used for three weeks, and then removed for a week. Vaginal ring and oral Nor-