Table 2 Characteristics and delivery interventions (%) in non-university hospitals (F-S) (included if ≥1, 000 deliveries/year) with different obstetric anal sphincter injuries (OASIS) rates in primiparous (n = 109, 596) and multiparous women (n = 146, 064) with singleton vaginal delivery between 1997 and 2007 in Finland (Chi Square test/Kruskall Wallis test).

PRIMIPAROUS,

n = 109, 596 (%)

15, 529 (14.2)

24, 315 (22.2)

69, 752 (63.6)

Hospitals, n

3 (G, L, P)

4 (I, M, N, R)

7 (F, H, J, K, O, Q, S)

OASIS, n = 1,137

61 (0.4)

185 (0.8)

891 (1.3)

≤0.001

1.0

Birth weight >4,000 g

13.0

11.6

12.8

≤0.001

12.5

Mean (± SD) of active second stage of birth (min)

40 ± 36

28 ± 29

45 ± 43

≤0.001

39 ± 39

Episiotomy

75.0

75.7

60.7

≤0.001

66.1

Vacuum assistance

12.9

16.1

14.8

≤0.001

14.8

Amniotomy

46.5

52.1

50.0

≤0.001

50.0

Augmentation with oxytocin

66.7

72.6

66.3

≤0.001

67.7

Epidural analgesia

57.4

61.1

55.8

≤0.001

57.2

Paracervical block

15.6

18.1

11.8

≤0.001

13.7

*Caesarean section

21.9

22.4

22.2

0.47

22.2

CHARACTERISTICS/INTERVENTIONS

Low: Hospitals with <0.1%

OASIS rate

Medium: Hospitals

with 0.1-0.2%

OASIS rate

High:

Hospitals

with 0.3-0.4%

OASIS rate

p value

Pooled

MULTIPAROUS,

n = 146, 064 (%)

12, 128 (8.3)

98, 793 (67.6)

35, 143 (24.1)

Hospitals, n

2 (G, L)

9(F, H, I, K, M, N, O, P, R)

3 (J, Q, S)

OASIS, n = 256

4 (0.03)

151 (0.15)

101 (0.29)

≤0.001

0.18

Birth weight >4,000 g

21.8

22.6

23.8

≤0.001

22.8

Mean (± SD) of active second stage of birth (min)

13 ± 18

13 ± 19

12 ± 15

≤0.001

13 ± 18

Episiotomy

21.1

17.4

16.5

≤0.001

17.5

Vacuum assistance

1.9

2.1

2.0

0.17

2.1

Amniotomy

45.8

54.5

56.1

≤0.001

54.1

Augmentation with oxytocin

28.4

39.4

37.0

≤0.001

37.9

Epidural analgesia

11.5

16.7

16.6

≤0.001

16.3

Paracervical block

24.8

22.5

16.5

≤0.001

21.3

*Caesarean section

10.1

10.0

8.6

≤0.001

9.7