| All PTB % | Medically indicated % | PPROM* % | Spontaneous†% | Comorbidity‡ % | Total births | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 | < 37 |    < 28 | 28-31 | 32-36 | < 37 |    < 28 | 28-31 | 32-36 | < 37 |    < 28 | 28-31 | 32-36 | < 37 | < 37 |  |
Systemic comorbidity | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   Hypertension |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preeclampsia/eclampsia | 24.1 |    1.0 | 3.3 | 16.3 | 20.6 |    0 | 0.1 | 1.2 | 1.3 |    0 | 0.1 | 2.1 | 2.2 | 8.7 | 29,915 |
Pre-existing | 11.0 |    0.2 | 0.7 | 5.8 | 6.7 |    0.1 | 0.1 | 1.9 | 2.1 |    0.1 | 0.1 | 1.9 | 2.1 | 0.8 | 7,439 |
Gestational | 6.1 |    0.1 | 0.2 | 3.2 | 3.5 |    0 | 0.1 | 1.1 | 1.2 |    0 | 0 | 1.3 | 1.4 | 1.0 | 11,380 |
   Cardiovascular disease | 10.3 |    0.2 | 0.6 | 4.4 | 5.3 |    0.2 | 0.3 | 2.1 | 2.6 |    0.2 | 0 | 2.2 | 2.5 | 0.6 | 4,434 |
   Diabetes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pre-existing | 13.1 |    0.1 | 0.6 | 5.5 | 6.1 |    0.1 | 0.5 | 3.1 | 3.7 |    0.1 | 0.3 | 2.9 | 3.2 | 2.7 | 16,938 |
Gestational | 8.4 |    0.1 | 0.2 | 2.6 | 2.8 |    0.1 | 0.2 | 2.4 | 2.7 |    0 | 0.1 | 2.8 | 2.9 | 5.1 | 50,313 |
   Edema/renal disease | 17.0 |    0.6 | 1.9 | 9.9 | 12.4 |    0.1 | 0.2 | 1.6 | 2.0 |    0.3 | 0.1 | 2.3 | 2.6 | 0.8 | 3,977 |
   Genitourinary infection | 8.4 |    0.2 | 0.5 | 2.7 | 3.3 |    0.2 | 0.4 | 2.0 | 2.6 |    0.2 | 0.1 | 2.1 | 2.5 | 3.2 | 31,477 |
   General infection | 10.0 |    0.2 | 0.4 | 3.2 | 3.8 |    0.3 | 0.4 | 2.2 | 2.9 |    0.3 | 0.2 | 2.7 | 3.2 | 1.9 | 16,024 |
   Thyroid disease | 8.9 |    0.2 | 0.4 | 3.0 | 3.7 |    0.2 | 0.3 | 2.3 | 2.8 |    0.2 | 0.2 | 2.2 | 2.5 | 1.4 | 12,687 |
   Anemia | 6.9 |    0.2 | 0.4 | 2.3 | 2.9 |    0.2 | 0.2 | 1.5 | 2.0 |    0.2 | 0.1 | 1.7 | 2.0 | 11.7 | 140,410 |
   Drug dependence | 21.4 |    0.2 | 0.8 | 4.5 | 5.5 |    0.6 | 0.7 | 5.0 | 6.2 |    0.6 | 0.7 | 8.5 | 9.8 | 3.9 | 3,229 |
   Mental disorders | 13.2 |    0.4 | 0.5 | 3.7 | 4.5 |    0.3 | 0.6 | 3.2 | 4.1 |    0.4 | 0.3 | 3.9 | 4.6 | 9.3 | 7,688 |
Localized comorbidity | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   Hemorrhage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Placental abruption | 31.9 |    1.3 | 2.4 | 9.9 | 13.6 |    1.3 | 1.6 | 3.6 | 6.6 |    2.3 | 1.8 | 7.6 | 11.7 | 8.6 | 22,278 |
Placenta previa | 35.2 |    0.8 | 2.9 | 26.3 | 30.0 |    0.9 | 0.5 | 2.4 | 3.8 |    0.3 | 0.2 | 1.1 | 1.5 | 2.3 | 5,265 |
   Chorioamnionitis | 11.0 |    0.3 | 0.3 | 1.4 | 1.9 |    1.2 | 1.2 | 3.1 | 5.5 |    1.0 | 0.5 | 2.1 | 3.6 | 7.3 | 55,133 |
   Amniotic sac |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Polyhydramnios | 12.5 |    0.3 | 0.8 | 4.9 | 6.0 |    0.2 | 0.3 | 2.0 | 2.5 |    0.3 | 0.5 | 3.4 | 4.1 | 1.3 | 8,861 |
Oligohydramnios | 20.6 |    0.8 | 1.8 | 10.4 | 13.0 |    1.1 | 1.4 | 3.2 | 5.7 |    0.3 | 0.2 | 1.5 | 1.9 | 3.8 | 15,293 |
   Cervical incompetence | 47.4 |    3.4 | 1.5 | 6.4 | 11.2 |    6.3 | 2.7 | 5.7 | 14.7 |    11.3 | 2.1 | 8.1 | 21.5 | 1.5 | 2,570 |
   Structural abnormality | 13.0 |    0.6 | 1.1 | 5.1 | 6.7 |    0.4 | 0.6 | 3.2 | 4.2 |    0.4 | 0.2 | 1.5 | 2.1 | 3.1 | 19,515 |
   Previous cesarean delivery | 5.8 |    0.1 | 0.2 | 2.9 | 3.3 |    0.1 | 0.1 | 1.3 | 1.5 |    0.1 | 0.1 | 0.9 | 1.0 | 8.4 | 118,608 |
   Fetal anomaly | 43.2 |    8.2 | 1.9 | 11.7 | 21.9 |    0.2 | 0.6 | 2.4 | 3.2 |    12 | 0.6 | 5.5 | 18.1 | 0.5 | 935 |
Total | 6.2 |    0.1 | 0.2 | 1.5 | 1.8 |    0.1 | 0.1 | 1.7 | 1.9 |    0.1 | 0.1 | 2.2 | 2.5 |  | 1,329,737 |