Table 1 Characteristics by maternal country of birth (n = 34,721)

  < 20 years

687(4.0%)

37(0.5%)

43(0.6%)

<0.001

 20–30years

7476(43.5%)

4181(53.1%)

2787(40.5%)

  > 30 years

9016(52.5%)

3656(46.4%)

4049(58.9%)

  < 19

561(3.3%)

461(5.9%)

798(11.7%)

<0.001

 19–24.9

7121(41.9%)

4161(53%)

4716(69.1%)

 25–29.9

4667(27.4%)

2404(30.6%)

1073(15.7%)

  ≥ 30

4662(27.4%)

820(10.5%)

240(3.5%)

Nulliparous

7300(42.5%)

3914(49.7%)

3247(47.2%)

<0.001

Interpreter required

88(0.5%)^a

1479(18.8%)

2441(35.5%)

<0.001

Private patient

2946(17.1%)

602(7.6%)

653(90.5%)

<0.001

Smoker

2797(16.3%)

24(0.3%)

75(1.1%)

<0.001

Previous cesarean

2341(13.6%)

1073(13.6%)

711(10.3%)

<0.001

First trimester ultrasound

14,926(86.9%)

6549(83.2%)

5481(79.7%)

<0.001

Pre-existing hypertension

230(1.3%)

36(0.5%)

29(0.4%)

<0.001

Pre-existing diabetes

181(1.1%)

81(1.0%)

39(0.6%)

0.001

Pre-existing thyroid disease

384(2.2%)

435(5.5%)

141(2.0%)

<0.001

Gestational diabetes

826(4.8%)

892(11.3%)

778(11.3%)

<0.001

Gestational Hypertension/Pre-eclampsia/HELLP

918(5.3%)

242(3.1%)

147(2.1%)

<0.001

Labor induced

4100(23.9%)

1841(23.3%)

1067(15.5%)

<0.001

Labor augmented

3286(19.1%)

1810(23%)

1714 (24.9%)

<0.001

Epidural

3626(21.1%)

1396(17.7%)

1015(14.8%)

<0.001

Length of 1^st stage of Labor (hours)^b

4.3(1.8–8.0)

5.3(2.3–9.2)

5.1(2.4–9.2)

<0.001

Length of 2^nd stage of Labor (mins)^b

15(0–48)

19(0–59)

20(4–58)

<0.001

 37–41 + 6 weeks

16,851(98.1%)

7760(98.6%)

6794(98.8%)

<0.001

  ≥ 42 weeks

328(1.9%)

114(1.4%)

85(1.2%)

Small for gestational age <10^th centile

1592(9.3%)

1266(16.1%)

896(13%)

<0.001

Birthweight of baby (g)

3491(498)

3309(460)

3312(426)

<0.001

Baby admission to NICU

146(0.8%)

62(0.8%)

44(0.6%)

<0.001

Apgar < 7 at 5 min

292(1.7%)

125(1.6%)

85(1.2%)

0.03

Fetal Compromise in Labour

4231(24.6%)

2369(30.1%)

1588(23.1%)

<0.001