Levonorgestrel releasing (20 μg/d) intrauterine system (LNG) v intrauterine devices ≤250 mm2 (IUD ≤250) or >250 mm2 (IUD >250) in women of reproductive age at 5 years of use*
| Outcomes | Comparison | Event rates | RRR (95% CI) | NNT:5 (CI) |
|---|---|---|---|---|
| Pregnancy | LNG v IUD ≤250† | 0.009% v 0.11% | 92% (81 to 97) | 17 (13 to 26) |
| LNG v IUD >250 | 0.017% v 0.026% | 34% (−74 to 75) | Not significant |
| RBI (CI) | NNT:5 (CI) | |||
|---|---|---|---|---|
| *NNT:5 = NNT for a 5 year period of use. Other abbreviations defined in glossary; RRR, RBI, RBR, NNT, NNH, and CI calculated from data in article. | ||||
| †2 studies were meta-analysed using a fixed-effects model and reported weighted event rates; other comparisons were based on 1 study. | ||||
| Continued use | LNG v IUD ≤250† | 1.11% v 0.96% | 16% (2 to 31) | 12 (7 to 61) |
| RBR (CI) | NNH:5 (CI) | |||
| LNG v IUD >250 | 0.85% v 0.88% | 3% (−14 to 17) | Not significant | |