Table 1 Characteristics of the study and control group (n=391)

Nulliparous (n, %)

219

56.0

216

55.2

-

Mode of birth (n, %)

-

 Spontaneous

322

82.8

301

77.0

 Instrumental vaginal

39

10.0

38

9.7

 Cesarean

28

7.2

52

13.3

 Missing

2

0

Obstetric injury (n, %)

-

 First degree perineal laceration, labia laceration

75

21.3

75

22.8

 Second degree perineal laceration, vaginal or clitoral laceration

165

46.9

168

51.1

 Third or fourth degree perineal laceration, cervical laceration

6

1.7

12

3.6

 None

106

30.1

74

22.5

 Missing*

39

62

Adverse outcome in the third stage (n, %)

30

7.7

31

8.0

-

 Missing

2

4

Postpartum hemorrhage (n, %)

52

13.5

44

11.5

-

 Missing

6

8

Duration of labor (min), (mean, SD)

433.6

334.9

443.9

317.0

0.663^#

 Missing

6

9

Episiotomy (n, %)

35

9.8

31

9.3

0.888

 Missing^a

33

56

Epidural anesthesia (n, %)

89

22.9

158

41.1

<0.001

 Missing

2

7

Hospital discharge within six hours after birth (n, %)

88

23.1

27

7.0

<0.001

 Missing

10

5

Length of hospital stay (days), admission to discharge (mean, SD)

2.8

1.2

3.3

1.2

<0.001

 Missing^b

104

42

Length of hospital stay (days), birth to discharge (mean, SD)

2.3

1.0

2.7

1.0

<0.001

 Missing^b

105

42

5-minute APGAR score < 7 (n, %)

2

0.5

5

1.3

-

 Missing

1

1

Umbilical cord arterial pH < 7.10 (n, %)

7

1.8

9

2.3

-

 Missing

6

4

Unplanned transfer to specialist neonatal care (n, %)

10

2.6

15

3.9

-

 Missing

6

5

Birthweight (gram), mean (SD)

3475.2

391.3

3461.9

399.7

0.664

 Missing

1

3

Birthweight percentile, mean (SD)

49.7

25.5

47.1

26.7

0.173

 Missing

91

89

1-minute APGAR score (mean, SD)

8.9

0.7

8.8

1.0

0.305

 Missing

1

2

5-minute APGAR score (mean, SD)

9.8

0.6

9.7

0.8

0.855

 Missing

1

1

10-minute APGAR score (mean, SD)

10.0

0.2

9.9

0.3

0.035

 Missing

1

1

Umbilical cord arterial pH (mean, SD)

7.3

0.1

7.3

0.1

0.080

 Missing

6

4

Umbilical cord arterial Base Excess (mean, SD)

-5.6

3.4

-5.4

3.4

0.163

 Missing

10

9