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Table 4 Unadjusted and adjusted odds ratios for risk factors for perineal tear

From: Risk factors for perineal and vaginal tears in primiparous women – the prospective POPRACT-cohort study

n = 443

2nd degree (n = 182)

OASI (n = 31)

OR (95% CI)

aOR (95% CI)

OR (95% CI)

aOR (95% CI)

Age

 ≤ 25 years

Reference

Reference

Reference

Reference

 > 25 years

1.78 (1.05, 3.04)*

1.62 (0.90, 2.93)

1.41 (0.51, 3.86)

1.36 (0.40, 4.56)

BMI

 ≤ 25 kg/m2

Reference

Reference

Reference

Reference

 25.1–30 kg/m2

1.02 (0.64, 1.61)

1.11 (0.68, 1.81)

1.21 (0.52, 2.8)

1.04 (0.41, 4.56)

 > 30 kg/m2

1.19 (0.63, 2.22)

1.22 (0.61, 2.41)

0.63 (0.14, 2.85)

0.38 (0.07, 1.99)

Education

 9to < 12 years

0.3 (0.03, 2.69)

0.35 (0.04, 3.47)

3.32 (0.57, 19.2)

4.01 (0.54, 29.8)

 12 years

0.86 (0.57, 1.3)

0.93 (0.59, 1.46)

0.58 (0.24, 1.42)

0.56 (0.20, 1.55)

 University

Reference

Reference

Reference

Reference

Hereditya (n = 397)

 No

Reference

NE

Reference

NE

 Yes

1.38 (0.77, 2.46)

NE

1.63 (0.57, 4.7)

NE

SUI in late pregnancy

 No

Reference

NE

Reference

NE

 Yes

0.69 (0.42, 1.12)

NE

1.59 (0.7, 3.63)

NE

GA at birth

 Preterm/term

Reference

Reference

Reference

Reference

 Postterm

2.23 (1.11, 4.47)*

2.44 (1.03, 5.77)*

2.29 (0.7, 7.45)

1.48 (0.34, 6.50)

Delivery start

 Spontaneous

Reference

Reference

Reference

Reference

 Induction

1.16 (0.7, 1.93)

0.73 (0.38, 1.40)

1.76 (0.73, 4.22)

1.31 (0.43, 4.00)

Epidural analgesia

 No

Reference

Reference

Reference

Reference

 Yes

1.20 (0.81, 1.77)

0.97 (0.63, 1.5)

2.41 (1.09, 5.35)*

1.62 (0.68, 3.87)

Oxytocin stimulation

 No

Reference

Reference

Reference

Reference

 Yes

1.53 (1.03, 2.26)*

1.18 (0.74, 1.9)

1.9 (0.89, 4.06)

0.85 (0.34, 2.13)

Duration of active 2nd stage

 ≤ 15 min

0.66 (0.39, 1.14)*

0.69 (0.39, 1.21)

1.08 (0.43, 2.76)

1.22 (0.44, 3.4)

 16–60 min

Reference

Reference

Reference

Reference

 > 60 min

1.09 (0.68, 1.74)

0.99 (0.6, 1.62)

0.84 (0.32, 2.23)

0.59 (0.21, 1.72)

Maternal position at birth

 Flexible

    

 sacrum

Reference

Reference

Reference

Reference

 positions

    

 Reduced

0.94 (0.59, 1.49)

0.53 (0.32, 0.90)*

1.07 (0.42, 2,75)

0.63 (0.21, 1.85)

 sacrum

    

 flexibility

    

Mode of delivery

 Spontaneous

Reference

Reference

Reference

Reference

 Vacuum

    

 extraction

2.37 (1.29, 4.34)*

2.41 (1.24, 4.68)*

3.86 (1.52, 9.8)*

3.91 (1.32, 11.6)*

Fetal scalp electrode

 No

Reference

Reference

Reference

Reference

 Yes

1.28 (0.87, 1.9)*

1.13 (0.73, 1.77)

3.03 (1.3, 7.05)*

2.55 (0.98, 6.61)

Fetal presentation

 Occiput anterior

Reference

Reference

Reference

Reference

 Occiput posterior

1.27 (0.44, 3.7)

1.38 (0.45, 4.21)

2.2 (0.44, 11.08)

3.22 (0.53, 19.5)

Hand or arm presenting fetal part

 No

Reference

NE

Reference

NE

 Yes

1.05 (0.57, 1.91)

NE

0.81 (0.23, 2.83)

NE

Fetal weight

 ≤ 4000 g

Reference

Reference

Reference

Reference

 > 4000 g

2.46 (1.35, 4.49)*

2.22 (1.17, 4.22)*

6.11 (2.55, 14.6)*

6.02 (2.32, 15.6)*

Fetal head circumference

 ≤ 35 cm

Reference

NE

Reference

NE

 > 35 cm

1.87 (1.26, 2.77)*

NE

3.94 (1.63, 9.51)*

NE

  1. Unadjusted and adjusted odds ratios for risk factors for perineal tear using multinomial logistic regression. The group of women with second-degree perineal tear and OASI were compared with women with no or first-degree perineal tear. Women having an episiotomy were excluded from the analysis. Sample size for the unadjusted OR for heredity, SUI, hand or arm presenting fetal part and fetal head circumference was based on n = 397, n = 415, n = 441 and n = 442, respectively. aHeredity of pelvic floor dysfunction and/or connective tissue deficiency; *Significant at level p < 0.05. aOR adjusted odds ratio, BMI body mass index, CI confidence interval, GA gestational age, NE not estimated, OASI obstetric anal sphincter injury, OR odds ratio, SUI stress urinary incontinence
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BMC Pregnancy and Childbirth

ISSN: 1471-2393

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