Table 1.
Elective CS: distribution of singleton deliveries and proportion of elective CS according to risk factors, all included in a multivariable logistic regression model
| Singleton deliveries | All deliveries | Elective CS | ||
| n (%) | n (% within category) | OR | 95% CI | |
| 226 612 (100) | 19 620 (8.7) | |||
| Year | ||||
| 2009 | 58 880 (27) | 5186 (8.8) | Ref | |
| 2010 | 59 139 (27) | 4973 (8.4) | 0.94 | 0.89 to 0.99 |
| 2011 | 55 099 (24) | 4773 (8.7) | 0.92 | 0.87 to 0.97 |
| 2012 | 53 574 (24) | 4688 (8.8) | 0.95 | 0.90 to 1.00 |
| Size of maternity unit | ||||
| Small | 13 638 (6) | 884 (6.5) | 0.74 | 0.68 to 0.81 |
| Medium | 97 653 (43) | 8746 (9.0) | Ref | |
| Large | 115 321 (51) | 9990 (8.7) | 1.08 | 1.04 to 1.12 |
| Weekend delivery (yes) | 60 993 (27) | 260 (0.4) | 0.03 | 0.03 to 0.04 |
| Night delivery (yes) | 100 718 (44) | 361 (0.4) | 0.02 | 0.02 to 0.02 |
| Maternal age (years) | ||||
| 15–19 | 3292 (1) | 93 (2.8) | 0.62 | 0.50 to 0.77 |
| 20–34 | 176 722 (78) | 13 179 (7.5) | Ref | |
| 35–44 | 46 598 (21) | 6348 (13.6) | 1.58 | 1.51 to 1.66 |
| Maternal smoking (yes) | 28 150 (12) | 2157 (7.7) | 0.99 | 0.93 to 1.05 |
| Maternal BMI | ||||
| 14.0–18.4 | 9321 (4) | 642 (6.9) | 1.02 | 0.92 to 1.13 |
| 18.5–24.9 | 142 597 (63) | 10 986 (7.7) | Ref | |
| 25.0–29.9 | 46 731 (21) | 4593 (9.8) | 1.17 | 1.11 to 1.22 |
| 30–34.9 | 18 291 (8) | 2093 (11.4) | 1.37 | 1.29 to 1.47 |
| 35.0+ | 9672 (4) | 1306 (13.5) | 1.56 | 1.43 to 1.70 |
| Maternal height≤163 cm (yes) | 55 288 (24) | 5389 (9.7) | 1.05 | 1.00 to 1.09 |
| Parity | ||||
| Nulliparous | 104 448 (46) | 5299 (5.1) | 1.08 | 1.03 to 1.14 |
| Multiparous without previous CS | 96 166 (42) | 3855 (4.0) | Ref | |
| Multiparous with previous CS | 25 998 (11) | 10 466 (40.3) | 16.9 | 16.08 to 17.75 |
| Complication factors | ||||
| Diabetes | 422 (0.2) | 42 (10.0) | ||
| Hypertension | 3954 (2) | 356 (9.0) | ||
| Pre-eclampsia/eclampsia | 6257 (3) | 385 (6.2) | ||
| Placenta praevia | 1128 (0.5) | 511 (45.3) | ||
| Placental abruption | 938 (0.4) | 16 (2) | ||
| Premature rupture of membranes | 17 548 (8) | 98 (0.6) | ||
| Complication (yes) | 29 461 (13) | 1374 (4.7) | 0.46 | 0.42 to 0.50 |
| Term | ||||
| <37+0 | 10 992 (5) | 615 (5.6) | 0.28 | 0.25 to 0.32 |
| 37+0–41+6 | 205 338 (91) | 18 897 (9.2) | Ref | |
| ≥42+0 | 10 282 (5) | 108 (1.1) | 0.12 | 0.10 to 0.15 |
| Female baby (yes) | 110 397 (49) | 9812 (8.9) | 1.01 | 0.97 to 1.05 |
| Breech presentation (yes) | 8979 (4) | 4382 (48.8) | 24.02 | 22.45 to 25.70 |
| Macrosomia (yes), >4500 g | 6220 (3) | 578 (9.3) | 1.11 | 0.98 to 1.25 |
OR with 95% CI based on a multivariable logistic regression model.
BMI, body mass index; CS, caesarean section; n, number; Ref, reference group.