Table 3.
Temporal Changes in Neonatal Mortality or Serious Neonatal Morbidity† by Plurality, Gestational Age and Subtype of Preterm Birth, United States, 1995-96 and 2004-05
| 1995-96 | 2004-05 | |||||
|---|---|---|---|---|---|---|
| Plurality and gestational age and preterm birth subtype | Live births | Neonatal outcomes†/100 live births | Live births | Neonatal outcomes†/100 live births | Odds ratio (2004-05 vs 1995-96) | 95% confidence intervals |
| Singletons | ||||||
| 24-27 wks: Iatrogenic | 6,418 | 49.0 | 7,532 | 42.9 | 0.78* | 0.73-0.83 |
| Spontaneous | 8,569 | 52.1 | 6,683 | 45.5 | 0.77* | 0.72-0.82 |
| PROM | 4,728 | 51.0 | 3,338 | 49.9 | 0.95 | 0.87-1.04 |
| 28-31 wks: Iatrogenic | 14,329 | 28.4 | 16,008 | 23.7 | 0.78* | 0.74-0.82 |
| Spontaneous | 16,486 | 23.1 | 12,501 | 20.5 | 0.86* | 0.82-0.91 |
| PROM | 8,083 | 26.9 | 5,402 | 26.3 | 0.97 | 0.89-1.04 |
| 32-33 wks: Iatrogenic | 14,973 | 15.8 | 18,051 | 13.3 | 0.82* | 0.77-0.87 |
| Spontaneous | 21,469 | 10.7 | 17,124 | 9.50 | 0.88* | 0.82-0.94 |
| PROM | 9,955 | 12.3 | 6,662 | 12.9 | 1.06 | 0.97-1.16 |
| 34-36 wks: Iatrogenic | 86,586 | 5.69 | 119,807 | 4.49 | 0.78* | 0.75-0.81 |
| Spontaneous | 173,286 | 2.73 | 152,483 | 2.43 | 0.89* | 0.85-0.93 |
| PROM | 35,844 | 4.83 | 22,801 | 5.64 | 1.18* | 1.09-1.27 |
| 24-36 wks: Iatrogenic | 122,306 | 11.9 | 161,398 | 9.17 | 0.75* | 0.73-0.77 |
| Spontaneous | 219,810 | 6.95 | 188,791 | 5.80 | 0.82* | 0.80-0.84 |
| PROM | 58,610 | 12.9 | 38,203 | 13.7 | 1.07* | 1.03-1.12 |
| Twins | ||||||
| 24-27 wks: Iatrogenic | 1,640 | 49.1 | 2,477 | 42.0 | 0.83* | 0.73-0.94 |
| Spontaneous | 1,671 | 64.1 | 1,303 | 51.7 | 0.69* | 0.60-0.80 |
| PROM | 933 | 59.3 | 844 | 55.2 | 0.85 | 0.70-1.02 |
| 28-31 wks: Iatrogenic | 3,875 | 25.2 | 5,967 | 21.6 | 0.86* | 0.78-0.94 |
| Spontaneous | 3,312 | 26.7 | 3,205 | 23.7 | 0.85* | 0.76-0.95 |
| PROM | 1,889 | 30.9 | 1,679 | 28.5 | 0.89 | 0.77-1.03 |
| 32-33 wks: Iatrogenic | 5,252 | 12.0 | 8,930 | 11.4 | 0.95 | 0.85-1.06 |
| Spontaneous | 4,981 | 10.8 | 4,540 | 10.9 | 1.02 | 0.90-1.16 |
| PROM | 1,986 | 14.7 | 1,839 | 13.7 | 0.92 | 0.77-1.10 |
| 34-36 wks: Iatrogenic | 24,983 | 4.25 | 42,236 | 3.65 | 0.84* | 0.78-0.91 |
| Spontaneous | 21,432 | 3.52 | 18,322 | 3.47 | 1.03 | 0.93-1.14 |
| PROM | 3,372 | 5.60 | 2,975 | 6.62 | 1.19 | 0.97-1.47 |
| 24-36 wks: Iatrogenic | 35,750 | 9.72 | 59,610 | 8.20 | 0.84* | 0.81-0.88 |
| Spontaneous | 31,396 | 10.3 | 27,370 | 9.36 | 0.92* | 0.87-0.97 |
| PROM | 8,180 | 19.8 | 7,337 | 19.0 | 0.95 | 0.88-1.03 |
†Neonatal mortality or serious neonatal morbidity included (neonatal death, 5-minute Apgar score ≤3, neonatal seizures or assisted ventilation for ≥30 minutes).
*p-value < 0.05
Births with missing information about serious neonatal morbidity were excluded. Births recorded on new birth certificates in 2004-05 were excluded due to a different definition of assisted ventilation.