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Table 3 Risk of severe perineal lacerations, maternal, fetal and delivery characteristics by mode of vaginal delivery

From: Duration of second stage of labor and instrumental delivery as risk factors for severe perineal lacerations: population-based study

Timec

Severe perineal lacerationsa

 

Instrumental delivery

Non- instrumental delivery

 

n

%

aORb

95% CI

n

%

aORb

95% CI

 0–< 1 h

1507

10.9

1.00

Ref

25465

4.8

1.00

Ref

 1–< 2 h

2042

14.7

1.38

1.11–1.71

13196

6.2

1.21

1.08–1.35

 2–< 3 h

2066

16.3

1.62

1.31–1.99

7358

6.9

1.34

1.18–1.53

 3–< 4 h

2164

16.6

1.61

1.32–2.02

4053

7.3

1.39

1.20–1.63

  ≥ 4 h

2171

16.3

1.51

1.22–1.86

2189

8.1

1.45

1.19–1.75

Maternal age

  < 24

1123

11.2

0.86

0.70–1.06

7723

18.3

0.73

0.63–0.84

 25–30

3044

30.3

1.00

Ref

14132

33.6

1.00

Ref.

 30–35

3918

39.0

1.05

0.91–1.21

14714

34.9

1.22

1.11–1.36

  > 35

1953

19.5

0.95

0.80–1.12

5570

13.2

1.17

1.02–1.33

BMI (kg/m2)

  < 19.9

1329

14.1

1.16

0.98–1.38

5773

14.5

1.07

0.95–1.21

 20–24.9

5718

60.6

1.00

Ref.

24303

61.1

1.00

Ref.

 25–29.9

1834

19.4

1.18

1.02–1.36

7265

18.2

1.10

0.95–1.21

  > 30

561

5.9

0.99

0.77–1.27

2460

6.2

1.18

0.99–1.40

Maternal height

 130–154

325

3.3

1.44

1.05–1.97

996

2.4

1.48

1.13–1.95

 155–159

1097

11.1

1.29

1.06–1.57

3714

8.9

1.42

1.22–1.66

 160–164

2524

25.4

0.99

0.84–1.16

9877

23.7

1.15

1.03–1.30

 165–169

2845

28.6

1.00

Ref

11987

28.7

1.00

Ref.

 170–200

3154

31.7

0.83

0.71–0.96

15155

36.3

0.95

0.86–1.06

Daily smoking

 Non-smoker

9631

96.5

1.00

Ref

39912

95.4

1.00

Ref.

 smoker

352

3.5

0.89

0.64–1.24

1907

4.5

0.64

0.49–0.84

Gestational age (weeks)

 37

339

9.1

0.59

0.39–0.88

1945

3.7

0.64

0.49–0.82

 38

740

11.6

0.75

0.58–0.97

4365

4.5

0.75

0.64–0.88

 39

1878

12.1

0.76

0.63–0.91

10078

4.8

0.80

0.71–0.90

 40

3158

15.5

1.00

Ref

13617

6.3

1.00

Ref.

 41

2617

17.3

1.09

0.94–1.26

9085

7.4

1.09

0.98–1.23

 42

1218

18.7

1.14

0.93–1.11

2901

7.9

1.14

0.96–1.35

Induction of labor

2204

16.3

0.95

0.82–1.11

6624

6.3

1.04

0.92–1.18

Epidural analgesia

7574

15.3

0.94

0.82–1.08

25182

5.9

0.88

0.80–0.97

Oxytocin augmentation

7998

15.4

1.01

0.87–1.18

23097

6.3

0.95

0.87–1.05

Occiput posterior position

685

20.7

1.89

1.54–2.32

973

8.9

1.45

1.13–1.85

Episiotomy

1893

13.9

0.81

0.70–0.94

28442

9.1

1.46

1.27–1.69

Birthweight > 4500 g

242

31.4

2.22

1.65–2.99

525

16.2

2.27

1.77–2.93

Head circumference >35.5 cm

3970

18.8

1.48

1.31–1.67

10643

8.6

1.51

1.37–1.66

  1. aPerineal lacerations third- and fourth degree
  2. bAdjusted for maternal age, BMI, maternal height, parental cohabitation, smoking, epidural analgesia, oxytocin augmentation, induction of labor, gestational age, episiotomy, occiput posterior position, head circumference, birthweight more than 4500 g and mode of delivery
  3. cTime from fully dilated cervix to birth
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BMC Pregnancy and Childbirth

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