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Table 1 Unadjusted/Adjusted Odds Ratios (OR) of OASR among vaginally delivered women (n = 514,741)

From: The role of nocturnal delivery and delivery during the holiday period in Finland on obstetric anal sphincter rupture rates- a population based observational study

DELIVERY INTERVENTION/
CHARASTERISTICS
Unadjusted OR
(95% CI)
Adjusted OR
(95% CI)
Adjusted
p-value
Mode of delivery    
Normal vaginal birth   1  
Forceps 9.48 (6.18-14.55) 22.55 (9.05-56.22) ≤ 0.001
Vacuum assistance 5.40 (4.98-5.86) 7.37 (6.26-8.67) ≤ 0.001
Episiotomy 2.54 (2.35-2.73) 1.95 (1.77-2.13) ≤ 0.001
Episiotomy and vaginal delivery   1  
Episiotomy and forceps 3.02 (2.41-3.80) 0.21 (0.07-0.59) 0.003
Episiotomy and vacuum assistance 2.34 (2.24-2.44) 0.40 (0.33-0.49) ≤ 0.001
Maternal age (years)    
≤ 19   1  
20-29 1.29 (1.02-1.64) 1.39 (1.09-1.77) 0.008
30-39 1.18 (0.92-1.30) 1.37 (1.07-1.74) 0.01
≥ 40 0.83 (0.59-1.17) 1.01 (0.71-1.44) 0.95
Birth weight (g)    
≤ 2999   1  
3000-3499 1.69 (1.42-2.02) 1.66 (1.40-1.98) ≤ 0.001
3500-3999 2.40 (2.02-2.84) 2.36 (2.00-2.80) ≤ 0.001
≥ 4000 2.87 (2.72-3.86) 3.22 (2.70-3.83) ≤ 0.001
Amniotomy 0.95 (0.89-1.03) 0.91 (0.84-0.98) 0.01
Augmentation with oxytocin 1.89 (1.75-2.04) 1.12 (1.07-1.27) ≤ 0.001
Epidural analgesia 1.96 (1.82-2.11) 1.37 (1.26-1.49) ≤ 0.001
*Spinal analgesia 0.68 (0.54-0.85) 0.77 (0.61-0.96) 0.02
Nitrous oxide gas 1.03 (0.96-1.11) 0.87 (0.80-0.93) ≤ 0.001
*Occiput posterior presentation 7.95 (5.89-10.74) 2.07 (1.52-2.81) ≤ 0.001
Time of day    
8-23.59   1  
00.00-7.59 0.85 (0.78-0.92) 0.89 (0.82-0.97) 0.01
Months    
All months excluding July   1  
July 0.86 (0.75-0.98) 0.85 (0.74-0.97) 0.02
  1. OR adjusted for mode of delivery, induction, amniotomy, oxytocin, episiotomy, occiput posterior presentation, epidural analgesia, spinal analgesia, paracervical block, maternal age, length of the active second stage of birth, and birth weight) and time of birth (month, day of the week, time).
  2. (*adjusted 2004-2007)