Participating units Non-participating units Total p
Maternal age (years) 31.0±4.8 30.2±4.8 30.8 ±4.8 <0.001
Maternal pre-pregnancy BMI 24.3±4.8 24.1±4.4 24.3±4.8 0.01
Parity
0 9554 (41.9%) 1813 (36.6%) 11367 (41.0%) <0.001
1+ 3139 (58.1%) 13225 (63.4%) 16364 (59.0%)
Gestational age at delivery (days) 280.6 281.0 280.7 0.002
Start of labour
Spontaneous 16272 (71.4%) 3731 (75.3%) 20003 (72.1%) <0.001
Induced 5152 (22.6%) 950 (19.2%) 6102 (22.0%)
Pre-labour cesarean delivery 1355 (5.9%) 271 (5.5%) 1626 (5.9%)
Mode of delivery
Spontaneous vaginal 17069 (74.9%) 3858 (77.9%) 20927 (75.5%) <0.001
Operative vaginal 2443 (10.7%) 432 (8.7%) 2875 (10.4%)
Cesarean 3267 (14.3%) 662 (13.4) 3929 (14.2%)
Birthweight (g) 3583±483 3589±464 3584±479 0.38
5 min Apgar score < 7 260 (1.1%) 51 (1.0%) 311 (1.1%) 0.55
Transfer to NICU 1740 (7.6%) 254 (5.1%) 1994 (7.2%) <0.001