From: Theory of obstetrics: An epidemiologic framework for justifying medically indicated early delivery
Population | Labor induction/cesarean deliveries per 1,000 fetuses | Perinatal deaths*/1,000 fetuses | Number needed to treat (marginal) | ||||
 | 1995–96 | 1999–00 | Change†| 1995–96 | 1999–00 | Change |  |
Singletons ≥ 28 weeks, all | 339.4 | 384.5 | 45.1 | 3.95 | 3.64 | 0.31‡ | 145 |
   ≥ 28 weeks, no medical risk factors | 294.6 | 337.7 | 43.0 | 2.98 | 2.68 | 0.29‡ | 146 |
   ≥ 28 weeks, with hypertension | 662.4 | 697.6 | 35.2 | 6.96 | 6.76 | 0.20 | 180 |
   ≥ 28 weeks, with diabetes | 532.4 | 578.4 | 46.0 | 6.67 | 6.49 | 0.18 | 257 |
   ≥ 28 weeks, with hyp. and diabetes | 744.6 | 779.3 | 34.7 | 8.83 | 9.96 | -1.13 | -31 |
Twins ≥ 28 weeks, all | 636.5 | 685.3 | 48.8 | 12.13 | 10.63 | 1.50‡ | 32 |
Singletons ≥ 34 weeks, all | 338.3 | 383.2 | 44.8 | 2.66 | 2.42 | 0.24‡ | 188 |
   ≥ 34 weeks, no medical risk factors | 294.5 | 337.5 | 42.0 | 2.09 | 1.86 | 0.23‡ | 181 |
   ≥ 34 weeks, with hypertension | 654.1 | 689.5 | 35.1 | 3.91 | 3.87 | 0.04 | 927 |
   ≥ 34 weeks, with diabetes | 533.3 | 579.8 | 45.7 | 5.25 | 5.14 | 0.11 | 403 |
   ≥ 34 weeks, with hyp. and diabetes | 740.9 | 776.6 | 35.0 | 6.86 | 7.29 | -0.43 | -81 |
Twins ≥ 34 weeks, all | 634.8 | 685.9 | 48.7 | 6.68 | 6.16 | 0.53 | 92 |