Koetsawang S, Ji G, Krishna U, Cuadros A, Dhall G I, Wyss R, Rodriquez la Puenta J, Andrade A T, Khan T, Kononova E S
Department of Obstetrics and Gynaecology, Siriraj Hospital, Bangkok, Thailand.
Contraception. 1990 Feb;41(2):105-24. doi: 10.1016/0010-7824(90)90141-h.
A multicentre clinical trial, including 19 centres in 13 countries, assessed the contraceptive efficacy and clinical acceptability of a Silastic 382 vaginal ring releasing 20 micrograms of levonorgestrel for at least 90 days. A total of 1005 women entered the study and 8176.74 woman-months of experience was gathered. The rate of intrauterine pregnancy at one year of use was 3.6 per 100 women (95% confidence interval 2.2-5.0), and of ectopic pregnancy, 0.2% (one case). The principal reasons for discontinuation were menstrual disturbances (17.2% at one year), vaginal symptoms (6.0%) and repeated expulsion of the ring (7.1%). The pregnancy rate with this 20 micrograms levonorgestrel-releasing vaginal ring compares favourably with that of a low estrogen combination oral contraceptive tested by WHO and is less than half that of a progestogen-only oral contraceptive in a WHO randomized study. It is concluded that the WHO intravaginal ring releasing an average of 20 micrograms of levonorgestrel per 24 hours is an effective method of contraception for at least one year of use.
一项多中心临床试验在13个国家的19个中心开展，评估了一种释放20微克左炔诺孕酮且有效期至少90天的硅橡胶382阴道环的避孕效果和临床可接受性。共有1005名女性参与该研究，累积了8176.74女性-月的使用经验。使用一年时的宫内妊娠率为每100名女性中有3.6例（95%置信区间2.2 - 5.0），异位妊娠率为0.2%（1例）。停用的主要原因是月经紊乱（一年时为17.2%）、阴道症状（6.0%）和环反复脱落（7.1%）。这种释放20微克左炔诺孕酮的阴道环的妊娠率与世界卫生组织测试的低雌激素复方口服避孕药相比更具优势，且在世界卫生组织的一项随机研究中低于单纯孕激素口服避孕药的一半。结论是，世界卫生组织的阴道环平均每24小时释放20微克左炔诺孕酮，是一种至少使用一年的有效避孕方法。
