Table 3.
Primary and exploratory outcomes (modified intention-to-treat population)
| Outcomes | Lateral episiotomy, no (%) (n=344) | No episiotomy, no (%) (n=358) | P value | Risk difference, %* | Risk ratio* |
|---|---|---|---|---|---|
| Primary outcome | |||||
| OASI | 21 (6) | 47 (13) | 0.002 | −7.0 (−11.7 to −2.5) | 0.46 (0.28 to 0.78) |
| OASI adjusted† | - | - | 0.031 | — | 0.47 (0.23 to 0.97) |
| Exploratory outcomes, maternal | |||||
| Intact perineum | 12 (4) | 6 (2) | 0.16 | 1.8 (−0.6 to 4.5) | 2.08 (0.79 to 5.48) |
| Caesarean section | 12 | 4 | — | — | — |
| First degree injury | 8 (2) | 46 (13) | <0.001 | −10.5 (−14.6 to −6.7) | 0.18 (0.09 to 0.38) |
| Caesarean section | 5 | 1 | — | — | — |
| Second degree injury or episiotomy | 303 (88) | 259 (72) | <0.001 | 15.7 (9.9 to 21.4) | 1.22 (1.13 to 1.31) |
| Caesarean section | 5 | 0 | — | — | — |
| Postpartum haemorrhage ≥1000 mL | 51 (17) | 60 (19) | 0.54 | −1.8 (−7.8 to 4.1) | 0.90 (0.64 to 1.26) |
| Postpartum haemorrhage (mL), mean (SD) | 647 (436) | 654 (510) | 0.86 | — | — |
| Missing | 37 | 33 | — | — | — |
| Perineal pain‡, NRS ≥7 | 144 (49) | 142 (45) | 0.44 | 3.1 (−4.8 to 11.0) | 1.07 (0.90 to 1.27) |
| Pain‡, median (range) | 6 (1-10) | 6 (1-10) | 0.20 | — | — |
| Missing | 47 | 45 | — | — | — |
| Birth experience‡, NRS ≤3 | 32 (12) | 42 (14) | 0.32 | −2.8 (−8.3 to 2.8) | 0.81 (0.52 to 1.24) |
| Birth experience‡, median (range) | 7 (1-10) | 7 (1-10) | 0.39 | — | — |
| Missing | 66 | 64 | — | — | — |
| Hospital stay ≥3 days | 64 (19) | 76 (22) | 0.37 | −2.8 (−8.7 to 3.2) | 0.87 (0.65 to 1.17) |
| Hospital stay, days, mean (SD) | 2.25 (1.22) | 2.36 (1.32) | 0.23 | — | — |
| Missing | 5 | 7 | — | — | — |
| Exploratory outcomes, neonatal | |||||
| Apgar <7 at 5 min | 6 (2) | 12 (3) | 0.18 | −1.6 (−4.3 to 0.8) | 0.52 (0.20 to 1.37) |
| Missing | 0 | 1 | - | - | - |
| Metabolic acidosis§ | 22 (9) | 26 (10) | 0.69 | −1.1 (−6.5 to 4.4) | 0.90 (0.52 to 1.54) |
| Missing | 108 | 108 | - | - | - |
| NICU admission | 31 (9) | 34 (10) | 0.61 | −0.5 (−4.8 to 3.9) | 0.94 (0.60 to 1.51) |
| Shoulder dystocia | 0 | 3 (1) | 0.09 | −0.8 (−2.4 to 0.3) | n/a |
| Scalp haematoma | 19 (6) | 11 (3) | 0.11 | 2.4 (−0.6 to 5.7) | 1.79 (0.87 to 3.71) |
| Fracture | 3 (1) | 1 (<1) | 0.30 | 0.6 (−0.8 to 2.3) | 3.11 (0.33 to 29.79) |
| OBPP | 1 (<1) | 0 | 0.31 | 0.3 (−0.8 to 1.6) | n/a |
| HIE | 1 (<1) | 1 (<1) | 0.98 | 0.3 (−0.8 to 1.6) | 1.04 (0.07 to 16.57) |
| Seizures | 1 (<1) | 2 (1) | 0.59 | −0.3 (−1.5 to 1.0) | 0.52 (0.05 to 5.71) |
CI=confidence interval; HIE=hypoxic ischaemic encephalopathy; NICU=neonatal intensive care unit; NRS=numerical rating scale (1-10); OASI=obstetric anal sphincter injury; OBPP=obstetric brachial plexus palsy; SD=standard deviation.
Primary outcome had 96% confidence intervals and exploratory outcomes had 95% confidence intervals.
Adjusted for study site.
Pain and birth experience were assessed by numerical rating scales in the postnatal ward (pain 0-10, where 0=no pain to 10=worst imaginable pain and birth experience 1-10, where 1=worst possible overall experience and 10=best possible overall experience).
Metabolic acidosis is defined as umbilical artery pH <7.05 or base deficit 12.0 mmol/L or more.