Table 1.

Maternal demographics and labour characteristics

Variable	All N = 27,648	Occiput posterior N = 1292	Occiput anterior N = 26,356	P value
Maternal age (years)
Mean (SD)	30.7 (5.0)	30.6 (5.0)	30.7 (5.0)	0.53
≥ 35	5404 (19.5)	251 (19.4)	5153 (19.6)	0.96
Nulliparity	12,806 (46.3)	750 (58.1)	12,056 (45.7)	< 0.001
Missing	6 (0.02)	2 (0.15)	4 (0.02)
Gestational length
Mean (SD), days	280 ± 8	281 ± 9	280 ± 8	0.005
< 41 weeks	19,836 (71.7)	885 (68.5)	18,951 (71.9)	0.008
Normal pregnancy	20,950 (85.2)	925 (80.4)	20,025 (85.5)	< 0.001
Missing	3064 (11)	141 (11)	2923 (11)
Induction of labour	4018 (14.6)	247 (19.2)	3771 (14.4)	< 0.001
Missing	198 (0.7)	7 (0.5)	191 (0.7)
Oxytocin
In the first stage of labour	7436 (26.9)	599 (46.4)	6837 (25.9)	< 0.001
In the second stage of labour	7880 (28.5)	483 (37.4)	7397 (28.1)	< 0.001
First and second stage	4255 (15.4)	258 (20.0)	3997 (15.2)	< 0.001
Epidural analgesia	9276 (33.6)	620 (48.0)	8656 (32.8)	< 0.001
Duration of pushing (min)
Mean (SD)	39.0 (113.8)	51.4 (123.1)	38.6 (113.5)	0.003
> 45 min	4947 (21.7)	255 (35.1)	4692 (21.2)	< 0.001
Missing	4811 (17)	565 (44)	4246 (16)
Mode of delivery
Spontaneous vaginal	23,323 (84.4)	635 (49.1)	22,688 (86.1)	< 0.001
Operative vaginal	2400 (8.7)	197 (15.2)	2203 (8.4)	< 0.001
Caesarean section	1924 (7.0)	460 (35.6)	1464 (5.6)	< 0.001
Missing	1	0	1
Birth weight (g)
Mean (SD)	3620 (487.2)	3645 (508.5)	3619 (486.1)	0.07
< 3295	6770 (25.3)	316 (25.0)	6454 (25.3)	0.80
3295–3925	13,242 (49.4)	603 (47.7)	12,639 (49.5)	0.24
> 3925	6794 (25.3)	344 (27.2)	6450 (25.3)	0.11
Missing	842 (3)	29 (2)	813 (3)

Data are presented as n (%) or mean ± standard deviation (SD)