| Medically indicated |    PPROM†|    Spontaneous‡ | ||||||
---|---|---|---|---|---|---|---|---|---|
 | < 28 wk | 28-31 wk | 32-36 wk |    < 28 wk | 28-31 wk | 32-36 wk |    < 28 wk | 28-31 wk | 32-36 wk |
Systemic comorbidity | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   Hypertension |  |  |  |  |  |  |  |  |  |
Preeclampsia/eclampsia | 17.6 (15.4-20.1) | 38.7 (35.6-42.1) | 18.5 (17.8-19.1) |    0.2 (0.1-0.5) | 0.6 (0.4-0.9) | 0.9 (0.8-1.0) |    0.3 (0.2-0.5) | 0.7 (0.5-1.1) | 1.1 (1.0-1.2) |
Pre-existing | 3.4 (2.1-5.4) | 6.7 (5.1-8.8) | 5.1 (4.6-5.6) |    1.3 (0.7-2.3) | 1.2 (0.7-2.0) | 1.1 (0.9-1.3) |    1.0 (0.5-1.7) | 0.9 (0.5-1.9) | 0.9 (0.8-1.1) |
Gestational | 1.1 (0.5-2.0) | 2.1 (1.4-3.1) | 2.8 (2.5-3.1) |    0.1 (0.0-0.6) | 0.5 (0.2-0.9) | 0.6 (0.5-0.7) |    0.2 (0.1-0.6) | 0.1 (0.0-0.5) | 0.6 (0.5-0.7) |
   Cardiovascular disease | 2.2 (1.2-4.3) | 3.4 (2.3-4.9) | 3.0 (2.6-3.4) |    1.6 (0.8-3.4) | 2.4 (1.5-4.0) | 1.3 (1.0-1.6) |    1.6 (0.8-2.9) | 2.0 (1.1-3.7) | 1.1 (0.9-1.3) |
   Diabetes |  |  |  |  |  |  |  |  |  |
Pre-existing | 1.2 (0.8-1.9) | 3.2 (2.6-3.9) | 3.9 (3.6-4.2) |    1.2 (0.8-1.8) | 3.5 (2.8-4.4) | 2.0 (1.9-2.2) |    0.9 (0.6-1.4) | 2.2 (1.7-3.1) | 1.4 (1.3-1.6) |
Gestational | 0.6 (0.4-0.8) | 1.2 (1.0-1.4) | 1.7 (1.6-1.8) |    0.5 (0.3-0.7) | 1.3 (1.0-1.6) | 1.5 (1.4-1.6) |    0.3 (0.2-0.4) | 0.8 (0.6-1.1) | 1.3 (1.3-1.4) |
   Edema/renal disease | 6.8 (4.4-10.3) | 11.9 (9.4-14.9) | 7.3 (6.6-8.1) |    1.4 (0.6-3.3) | 1.7 (0.9-3.3) | 1.1 (0.8-1.4) |    1.8 (1.0-3.4) | 0.9 (0.3-2.4) | 1.1 (0.9-1.4) |
   Genitourinary infection | 1.7 (1.3-2.3) | 2.6 (2.2-3.1) | 1.8 (1.7-1.9) |    2.1 (1.6-2.7) | 2.6 (2.1-3.1) | 1.2 (1.1-1.3) |    1.3 (1.0-1.7) | 1.0 (0.7-1.4) | 1.0 (0.9-1.1) |
   General infection | 2.5 (1.8-3.5) | 2.2 (1.7-2.8) | 2.2 (2.0-2.4) |    3.0 (2.3-4.0) | 2.8 (2.2-3.6) | 1.4 (1.2-1.5) |    1.7 (1.3-2.4) | 2.1 (1.5-2.9) | 1.3 (1.2-1.4) |
   Thyroid disease | 2.3 (1.6-3.4) | 2.1 (1.6-2.8) | 1.9 (1.7-2.1) |    1.9 (1.3-2.9) | 1.9 (1.3-2.6) | 1.3 (1.2-1.5) |    1.1 (0.7-1.7) | 1.6 (1.0-2.5) | 1.1 (1.0-1.2) |
   Anemia | 2.2 (1.9-2.6) | 2.7 (2.4-2.9) | 1.6 (1.5-1.7) |    2.1 (1.8-2.4) | 1.7 (1.5-1.9) | 0.9 (0.9-0.9) |    1.3 (1.2-1.5) | 1.0 (0.8-1.2) | 0.7 (0.7-0.8) |
   Drug dependence | 1.8 (0.8-4.4) | 5.1 (3.5-7.5) | 3.3 (2.8-3.9) |    5.9 (3.7-9.3) | 4.9 (3.2-7.4) | 3.3 (2.8-3.9) |    3.9 (2.4-6.2) | 6.1 (4.0-9.2) | 4.1 (3.6-4.6) |
   Mental disorders | 3.6 (2.5-5.3) | 2.6 (1.9-3.6) | 2.4 (2.1-2.7) |    3.3 (2.2-4.8) | 4.1 (3.0-5.5) | 1.9 (1.7-2.2) |    2.7 (1.9-3.8) | 2.6 (1.7-3.9) | 1.8 (1.6-2.0) |
Localized comorbidity | Â | Â | Â | Â | Â | Â | Â | Â | Â |
   Hemorrhage |  |  |  |  |  |  |  |  |  |
Placental abruption | 27.7 (24.2-31.8) | 25.2 (22.9-27.9) | 10.7 (10.2-11.3) |    24.7 (21.6-28.2) | 19.7 (17.5-22.2) | 3.0 (2.8-3.2) |    30.4 (27.4-33.7) | 28.4 (25.3-31.8) | 5.1 (4.9-5.4) |
Placenta previa | 17.7 (12.9-24.2) | 30.4 (25.6-36.1) | 29.8 (27.9-31.8) |    16.8 (12.5-22.7) | 6.6 (4.5-9.6) | 2.1 (1.8-2.5) |    3.4 (2.0-5.9) | 3.0 (1.5-5.7) | 0.8 (0.6-1.0) |
   Chorioamnionitis | 3.8 (3.3-4.5) | 1.5 (1.3-1.8) | 0.9 (0.9-1.0) |    24.0 (21.5-26.8) | 12.4 (11.2-13.6) | 2.0 (1.9-2.1) |    9.6 (8.7-10.6) | 4.5 (3.9-5.2) | 1.0 (1.0-1.1) |
   Amniotic sac |  |  |  |  |  |  |  |  |  |
Polyhydramnios | 3.1 (2.0-4.7) | 5.1 (4.0-6.5) | 3.6 (3.3-4.0) |    1.7 (1.0-3.0) | 2.4 (1.6-3.5) | 1.3 (1.1-1.5) |    2.1 (1.4-3.1) | 4.1 (3.0-5.6) | 1.6 (1.5-1.8) |
Oligohydramnios | 10.2 (8.4-12.4) | 13.0 (11.5-14.8) | 8.6 (8.1-9.1) |    15.1 (12.8-17.8) | 12.6 (10.9-14.6) | 2.2 (2.0-2.4) |    2.6 (2.0-3.5) | 1.7 (1.1-2.5) | 0.8 (0.7-0.9) |
   Cervical incompetence | 68.6 (54.6-86.1) | 13.6 (9.8-18.9) | 7.1 (6.1-8.4) |    123 (103-146) | 33.4 (26.1-42.7) | 6.1 (5.1-7.2) |    159 (139-183) | 32.4 (24.5-42.9) | 6.9 (5.9-7.9) |
   Structural abnormality | 6.8 (5.5-8.3) | 6.3 (5.4-7.3) | 3.5 (3.2-3.7) |    4.2 (3.3-5.2) | 4.2 (3.4-5.1) | 2.0 (1.9-2.2) |    2.5 (2.0-3.2) | 2.2 (1.6-2.9) | 0.8 (0.7-0.9) |
   Previous cesarean delivery | 1.2 (1.0-1.4) | 1.3 (1.1-1.4) | 2.0 (2.0-2.1) |    1.1 (0.9-1.3) | 0.9 (0.7-1.0) | 0.8 (0.7-0.8) |    0.4 (0.3-0.5) | 0.5 (0.4-0.6) | 0.4 (0.4-0.4) |
   Fetal anomaly | 159 (123-204) | 16.3 (10.2-26.2) | 12.4 (10.1-15.3) |    3.2 (0.8-12.8) | 7.0 (3.1-15.6) | 2.3 (1.5-3.5) |    142 (115-176) | 8.7 (3.9-19.6) | 4.1 (3.1-5.5) |