Pregnancy rates for various emergency contraceptive methods after unprotected intercourse*
| Comparisons | Number of trials (n) | Weighted event rates | RRR (95% CI) | NNT (CI) |
|---|---|---|---|---|
| *Abbreviations defined in glossary; weighted event rates, RRR, NNT, and CI calculated from data in article using a fixed effects model. | ||||
| Intrauterine device v expectant management | 1 (300) | 2% v 22% | 91% (74 to 97) | 5 (4 to 9) |
| Levonorgestrel v the Yuzpe regimen | 2 (2789) | 1.3% v 3.3% | 49% (17 to 69) | 50 (34 to ∞) |
| Mifepristone v the Yuzpe regimen | 3 (2144) | 0.45% v 2.5% | 86% (59 to 95) | 50 (34 to 100) |
| Mifepristone, 25–50 mg v ⩽10 mg | 10 (8762) | 0.73% v 1.7% | 38% (12 to 57) | 100 (100 to ∞) |
| Mifepristone v anordrin | 3 (439) | 0.09% v 4.1% | 80% (8 to 96) | 25 (15 to 100) |
| Mifepristone v danazol | 2 (629) | 0.47% v 4.5% | 90% (45 to 98) | 25 (15 to 50) |