Table 4 Adjusted Odds Ratios (OR) of obstetric anal sphincter injuries (OASIS) (n = 1,137/n = 256) among primiparous (n = 109,596) and multiparous women with vaginal delivery (n = 146,064) in Non-University central Hospitals divided into three groups based on OASR rates (Low, Medium, High) between 1997 and 2007 in Finland.
CHARACTERISTICS/INTERVENTIONS | Adjusted OR | 95% CI | p value |
|---|---|---|---|
PRIMIPAROUS, n = 109,596 | |||
Mode of delivery | |||
Vaginal spontaneous | 1 | ||
Forceps | 24.40 | 6.90-86.29 | ≤0.001 |
Vacuum assistance | 4.76 | 3.70-6.14 | ≤0.001 |
Episiotomy and vaginal spontaneous | 1 | ||
Episiotomy and forceps | 0.18 | 0.04-0.75 | 0.018 |
Episiotomy and vacuum assistance | 0.50 | 0.38-0.65 | ≤0.001 |
Epidural analgesia | 0.79 | 0.70-0.89 | ≤0.001 |
Maternal age (year) | |||
≤19 | 1 | ||
20-29 | 1.74 | 1.22-2.49 | 0.002 |
30-39 | 2.23 | 1.56-3.21 | ≤0.001 |
≥40 | 1.56 | 0.78-3.12 | 0.21 |
Birth weight (g) | |||
≤2,999 | 1 | ||
3,000-3,499 | 1.91 | 1.47-2.47 | ≤0.001 |
3,500-3,999 | 2.74 | 2.12-3.53 | ≤0.001 |
≥4,000 | 4.27 | 3.27-5.59 | ≤0.001 |
Hospitals OASIS rate | |||
Low: ≤0.5% | 1 | ||
Medium: 0.6-1% | 1.84 | 1.38-2.47 | ≤0.001 |
High: 1.1-1.4% | 2.97 | 2.29-3.85 | ≤0.001 |
MULTIPAROUS, n = 146, 064 | |||
Mode of delivery | |||
Vaginal spontaneous | 1 | ||
Vacuum assistance | 8.33 | 4.78-14.54 | ≤0.001 |
Episiotomy and vaginal spontaneous | 1 | ||
Episiotomy and vacuum assistance | 0.41 | 0.20-0.83 | 0.01 |
Episiotomy | 2.82 | 2.12-3.76 | ≤0.001 |
Epidural analgesia | 1.38 | 1.03-1.84 | 0.03 |
Birth weight (g) | |||
≤2,999 | 1 | ||
3,000-3,499 | 2.03 | 0.80-5.21 | 0.14 |
3,500-3,999 | 3.92 | 1.61-9.76 | 0.003 |
≥4,000 | 7.56 | 3.15-19.0 | ≤0.001 |
Hospitals OASIS rate | |||
Low: ≤0.1% | 1 | ||
Medium: 0.1-0.2% | 4.37 | 1.62-11.81 | 0.004 |
High: 0.3-0.4% | 8.24 | 3.03-22.41 | ≤0.001 |