Table 3. Crude and adjusted Odds Ratios (99% CI) for second pregnancy outcomes for women with and without an initial third- or fourth-degree tear.
| Second pregnancy characteristic | Unadjusted OR (99%CI) | Adjusted OR(99%CI)a |
|---|---|---|
| Third/fourth degree tear | ||
| Yes | 4.49 (3.57–5.64) | 4.84 (3.64–6.46) |
| No | 1 | 1 |
| Age | ||
| (Missing = 1) | ||
| Mean (SD) | 1.05 (1.04–1.06) | 1.02 (1.00–1.03) |
| Smoking | ||
| Missing = 6584 (5.4%) | ||
| Non smoker | 1 | 1 |
| Smoker | 0.49 (0.42–0.56) | 0.67 (0.58–0.77) |
| Ex-smoker | 0.87 (0.75–1.02) | 0.83 (0.72–0.96) |
| Deprivation | ||
| Missing = 302 (0.2) | ||
| Most deprived (1–5) | 0.81 (0.74–0.89) | 0.90 (0.82–0.98) |
| Least deprived (6–10) | 1 | 1 |
| Diabetes | ||
| Missing = 19873 (16.3%) | ||
| Yes | 0.93 (0.60–1.45) | 0.79 (0.53–1.17) |
| No | 1 | 1 |
| BMI | ||
| Missing = 44646 (36.6%) | ||
| Mean (SD) | 1.00 (0.99–1.01) | 0.99 (0.98–1.00) |
| Mode of delivery | ||
| Missing = 24 (0.0%) | ||
| SVD | 1 | 1 |
| Forceps (non rot) | 1.20 (0.86–1.68) | 0.36 (0.25–0.51) |
| Ventouse (all) | 1.01 (0.68–1.51) | 0.65 (0.44–0.96) |
| Forceps (rotational) | 1.41 (0.71–2.77) | 0.45 (0.25–0.82) |
| Breech vaginal | 1.10 (0.08–14.85) | 0.63 (0.08–4.65) |
| Elective CS | 9.70 (8.68–10.83) | 12.75 (11.29–14.40) |
| Emergency CS | 1.49 (1.22–1.82) | 2.42 (2.01–2.93) |
| Weight of baby (grams) | ||
| Missing = 87 (0.1%) | ||
| <4500g | 1 | 1 |
| ≥4500g | 1.14 (0.87–1.49) | 0.84 (0.59–1.18) |
| Gestation at birth (weeks) | ||
| Missing = 119 (0.1) | ||
| Mean (SD) | 0.99 (0.97–1.01) | 1.01 (1.00–1.03) |
| Episiotomy | ||
| Missing = 1812 (1.5%) | ||
| Yes | 2.20 (1.93–2.50) | 3.74 (3.25–4.32) |
| No | 1 | 1 |
| Induction of labour | ||
| Missing = 447 (0.4) | ||
| None | 1 | 1 |
| ARM only | 0.59 (0.45–0.77) | 0.73 (0.56–0.93) |
| ARM + pharmacological methods | 0.59 (0.52–0.68) | 0.78 (0.68–0.89) |
| Position at delivery | ||
| Missing = 7228 (5.9) | ||
| OA | 1 | 1 |
| OP | 1.11 (0.85–1.44) | 0.88 (0.64–1.23) |
| OT | 1.24 (0.99–1.57) | 0.97 (0.72–1.31) |
| Other | 0.30 (0.22–0.41) |
aCovariates included in the multivariate model were third- or fourth-degree tear in 2nd pregnancy, age, smoking, deprivation, diabetes, BMI, mode of delivery, weight of baby, gestation, episiotomy, induction of labour and position at delivery (all in second pregnancy)
Missing data not included in the proportions presented.