Table 1. Characteristics of the overall cohort and the midwife-led and medical-led groups.
| Maternal Characteristic | Overall | Midwife-Led | Medical-Led | |||
|---|---|---|---|---|---|---|
| n (%) | n (%) | Age Standardized (%) | n (%) | Age Standardized (%) | p-Value | |
| Age | <0.001 | |||||
| <20 y | 16,380 (6.7) | 15,842 (7.1) | – | 538 (2.6) | – | – |
| 20 to 35 y | 187,156 (76.7) | 173,623 (77.7) | – | 13,533 (65.5) | – | – |
| >35 y | 40,502 (16.6) | 33,912 (15.2) | – | 6,590 (31.9) | – | – |
| Missing data | 9 (0.0) | 8 (0.0) | – | 1 (0.0) | – | – |
| Ethnicity | <0.001 | |||||
| European | 132,159 (54.2) | 117,547 (52.6) | 53.1 | 14,612 (70.7) | 65.7 | – |
| Māori | 60,985 (25.0) | 58,902 (26.4) | 25.9 | 2,083 (10.1) | 14.8 | – |
| Pacific | 21,308 (8.7) | 20,498 (9.2) | 9.1 | 810 (3.9) | 4.6 | – |
| Asian | 18,660 (7.7) | 16,590 (7.4) | 7.5 | 2,070 (10.0) | 9.6 | – |
| Indian | 6,741 (2.8) | 6,012 (2.7) | 2.7 | 729 (3.5) | 3.6 | – |
| Other | 4,163 (1.7) | 3,806 (1.7) | 1.7 | 357 (1.7) | 1.7 | – |
| Missing data | 31 (0.0) | 30 (0.0) | – | 1 (0.0) | – | – |
| NZ Deprivation Decile | <0.001 | |||||
| 1 to 2 | 37,191 (15.2) | 31,542 (14.1) | 14.4 | 5,649 (27.3) | 22.9 | – |
| 3 to 4 | 41,298 (16.9) | 36,809 (16.5) | 16.7 | 4,489 (21.7) | 19.4 | – |
| 5 to 6 | 48,348 (19.8) | 43,949 (19.7) | 19.8 | 4,399 (21.3) | 21.8 | – |
| 7 to 8 | 56,065 (23.0) | 52,250 (23.4) | 23.3 | 3,815 (18.5) | 22.4 | – |
| 9 to 10 | 60,638 (24.9) | 58,344 (26.1) | 25.9 | 2,294 (11.1) | 13.5 | – |
| Missing data | 507 (0.2) | 491 (0.2) | – | 16 (0.1) | – | – |
| Parity | <0.001 | |||||
| Nulliparous | 100,168 (41) | 90,798 (40.6) | 40.0 | 9,370 (45.3) | 51.2 | – |
| Prima or multiparous | 143,858 (59) | 132,567 (59.3) | 60.0 | 11,291 (54.6) | 48.8 | – |
| Missing data | 21 (0.0) | 20 (0.0) | – | 1 (0.0) | – | – |
| Body mass index | <0.001 | |||||
| <19 | 6,838 (2.8) | 6,214 (2.8) | 2.8 | 624 (3.0) | 3.3 | – |
| 19 to 24 | 114,220 (46.8) | 103,002 (46.1) | 46.2 | 11,218 (54.3) | 51.8 | – |
| ≥25 | 122,557 (50.2) | 113,849 (51.0) | 51.0 | 8,708 (42.1) | 44.9 | – |
| Missing data | 432 (0.2) | 320 (0.1) | – | 112 (0.5) | – | – |
| Trimester of LMC Registration | <0.001 | |||||
| 1 | 142,641 (58.5) | 129,238 (57.9) | 58.6 | 13,403 (64.9) | 60.4 | – |
| >1 | 99,302 (40.7) | 92,050 (41.2) | 41.4 | 7,252 (35.1) | 39.6 | – |
| Missing | 2,104 (0.9) | 2097 (0.9) | – | 7 (0.0) | – | – |
| Smoking Status | <0.001 | |||||
| No | 206,714 (84.7) | 187,182 (83.8) | 84.2 | 19,532 (94.5) | 90.7 | – |
| Yes | 37,263 (15.3) | 36,152 (16.2) | 15.8 | 1,111 (5.4) | 9.3 | – |
| Missing data | 70 (0.0) | 51 (0.0) | – | 19 (0.1) | – | – |
| Pre-existing Diabetes and/or Hypertension | 0.465 | |||||
| No | 242,327 (99.3) | 221,848 (99.3) | 99.3 | 20,479 (99.1) | 99.3 | – |
| Yes | 1,720 (0.7) | 1,537 (0.7) | 0.7 | 183 (0.9) | 0.7 | – |
| Gestational Age at Delivery (whole weeks) | <0.001 | |||||
| 37 | 13,486 (5.5) | 12,113 (5.4) | 5.4 | 1,373 (6.7) | 6.3 | – |
| 38 | 37,299 (15.3) | 32,941 (14.8) | 14.8 | 4,358 (21.1) | 19.3 | – |
| 39 | 65,707 (26.9) | 59,524 (26.7) | 26.7 | 6,183 (29.9) | 28.5 | – |
| 40 | 78,583 (32.2) | 72,744 (32.6) | 32.5 | 5,839 (28.3) | 30.1 | – |
| 41 | 41,882 (17.2) | 39,222 (17.6) | 17.5 | 2,660 (12.9) | 14.3 | – |
| 42+ | 7,090 (2.9) | 6,841 (3.1) | 3.1 | 249 (1.2) | 1.5 | – |