Levonorgestrel-releasing (20 μg/day) intrauterine systems (Mirena) compared with other methods of reversible contraceptives


Correspondence: Dr R. French, Department of Sexually Transmitted Diseases, Royal Free and University College Medical School, The Mortimer Market Centre, off Capper Street, London WC1E 6AU, UK.


Objective To assess the relative contraceptive effectiveness, tolerability and acceptability of the levonorgestrel-releasing (20 μg per day) intrauterine system (LNG-20) compared with reversible contraceptive methods in women of reproductive age.

Design A systematic review and meta-analysis of randomised controlled trials.

Identification Studies were identified through seven databases, and by contacting investigators and organisations working in the contraceptive field.

Main outcome measures Unplanned pregnancy and continuation of contraceptive method.

Results 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 380 A intrauterine devices) and those ≤ 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 ≤ 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.

Conclusions 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.