French R S, Cowan F M, Mansour D, Higgins J P, Robinson A, Procter T, Morris S, Guillebaud J
Department of Sexually Transmitted Diseases, Royal Free and University College London Medical School, The Mortimer Market Centre, UK.
BJOG. 2000 Oct;107(10):1218-25. doi: 10.1111/j.1471-0528.2000.tb11610.x.
To assess the relative contraceptive effectiveness, tolerability and acceptability of the levonorgestrel-releasing (20 microg per day) intrauterine system (LNG-20) compared with reversible contraceptive methods in women of reproductive age.
A systematic review and meta-analysis of randomised controlled trials.
Studies were identified through seven databases, and by contacting investigators and organisations working in the contraceptive field.
Unplanned pregnancy and continuation of contraceptive method.
Five of the seven randomised controlled trials which met the inclusion criteria were included in the meta-analyses; four were comparisons of the LNG-20 intrauterine system with nonhormonal intrauterine devices. LNG-20 intrauterine systems were compared with intrauterine devices divided into two categories, those > 250 mm3 (Copper T 380 Ag and Copper T 380A intrauterine devices) and those < or = 250 mm3 (Nova-T, Copper T 220C and Copper 200 intrauterine devices). Pregnancy rates for the LNG-20 intrauterine system users were significantly less likely to become pregnant compared with users of intrauterine devices < or = 250 mm3, and significantly less likely to have an ectopic pregnancy. LNG-20 intrauterine system users were more likely to experience amenorrhoea and device expulsion than women using intrauterine devices > 250 mm3. LNG-20 intrauterine system users were significantly more likely than all the intrauterine device users to discontinue because of hormonal side effects and amenorrhoea. When the LNG-20 intrauterine system was compared with Norplant-2, the LNG-20 users were significantly more likely to experience oligo-amenorrhoea, but significantly less likely to experience prolonged bleeding and spotting.
The effectiveness of the LNG-20 intrauterine system was similar to or better than other contraceptive methods with which it was compared. Amenorrhoea was the main reason for the discontinuation of the LNG-20 intrauterine system, usually unnecessarily, since this end-organ suppression of bleeding is benign, associated with normal oestrogen levels. Women choosing this method should be informed of potential amenorrhoea when having pre-contraceptive counselling and that absent bleeding may be viewed as a positive outcome.
评估左炔诺孕酮释放宫内系统（LNG-20，每日释放20微克左炔诺孕酮）与可逆性避孕方法相比，在育龄妇女中的相对避孕效果、耐受性和可接受性。
对随机对照试验进行系统评价和荟萃分析。
通过七个数据库以及联系避孕领域的研究人员和组织来识别研究。
意外妊娠和避孕方法的持续使用情况。
符合纳入标准的七项随机对照试验中有五项纳入了荟萃分析；四项是LNG-20宫内系统与非激素宫内节育器的比较。LNG-20宫内系统与分为两类的宫内节育器进行了比较，一类体积＞250立方毫米（铜T 380 Ag和铜T 380A宫内节育器），另一类体积≤250立方毫米（诺瓦-T、铜T 220C和铜200宫内节育器）。与体积≤250立方毫米的宫内节育器使用者相比，LNG-20宫内系统使用者怀孕的可能性显著降低，发生宫外孕的可能性也显著降低。与使用体积＞250立方毫米宫内节育器的女性相比，LNG-20宫内系统使用者闭经和节育器脱落的发生率更高。与所有宫内节育器使用者相比，LNG-20宫内系统使用者因激素副作用和闭经而停用的可能性显著更高。当将LNG-20宫内系统与Norplant-2进行比较时，LNG-20使用者发生月经过少的可能性显著更高，但发生长时间出血和点滴出血的可能性显著更低。
LNG-20宫内系统的有效性与所比较的其他避孕方法相似或更好。闭经是停用LNG-20宫内系统的主要原因，通常是不必要的，因为这种对出血的终末器官抑制是良性的，与正常雌激素水平相关。选择这种方法的女性在进行避孕前咨询时应被告知可能出现闭经，且无出血可被视为一个积极结果。
