Numbers of deliveries to patients with a previous cesarean delivery, and associated rates of vaginal birth after cesarean delivery, severe maternal morbidity and mortality, and serious neonatal morbidity and mortality by tier of obstetric service, Canada (excluding Quebec), April 2013 to March 2019
| Variable | No. of patients with a previous cesarean delivery | No. (rate per 100 deliveries) of patients with VBAC* | No. (rate per 1000 deliveries) of patients with SMMM* | No. of live births without congenital anomalies | No. (rate per 1000 live births) of infants with SNMM* |
|---|---|---|---|---|---|
| Overall | |||||
| Tier 0 | 29 | 9 (31.0) | < 5 (< 172.4)† | 27 | 0 (0) |
| Tier 1 | 21 787 | 3971 (18.2) | 192 (8.8) | 20 327 | 62 (3.1) |
| Tier 2 | 77 524 | 13 479 (17.4) | 983 (12.7) | 73 186 | 321 (4.4) |
| Tier 3 | 65 297 | 10 526 (16.1) | 777 (11.9) | 61 182 | 315 (5.1)† |
| Tier 4 | 70 805 | 15 352 (21.7) | 1480* (20.9)† | 64 886 | 303 (4.7) |
| Total | 235 442 | 43 337 (18.4) | 3437 (14.6) | 219 608 | 1001 (4.6) |
| Parity of 1 | |||||
| Tier 0 | 13 | < 5 (< 38.5) | < 5 (< 384.6)† | 11 | 0 (0) |
| Tier 1 | 11 534 | 1725 (15.0) | 99 (8.6) | 10 747 | 36 (3.3) |
| Tier 2 | 44 573 | 6607 (14.8) | 541 (12.1) | 42 056 | 180 (4.3) |
| Tier 3 | 39 667 | 5481 (13.8) | 430 (10.8) | 37 167 | 185 (5.0) |
| Tier 4 | 42 675 | 8100* (19.0) | 840* (19.6)† | 39 121 | 177 (4.5) |
| Total | 138 462 | 21 921 (15.8) | 1909 (13.8) | 129 102 | 578 (4.5) |
Note: SNMM = serious neonatal morbidity and mortality, SMMM = severe maternal morbidity and mortality, VBAC = vaginal birth after cesarean delivery.
↵* Cells < 5 suppressed to prevent reidentification of patients, and some cells rounded to the nearest 10 to prevent back calculation.
↵† The rate was significantly higher than the rate in all the other tiers of service combined based on Fisher exact test (p < 0.05).