| BMI (mean±SD) | 26.2±3.3 | 26.4±3.4 | 26.1±3.1 | 1 | 0.97–1.10 | 0.33 |
| Medical history | 53 (13.8) | 27 (13.0) | 26 (14.8) | 0.61 | 0.48–1.54 | 0.09 |
| Surgical history | 32 (8.3) | 20 (9.6) | 12 (6.8) | 1.45 | 0.69–3.10 | 0.33 |
| Delivery history | | | | | | |
| No | 190 (49.5) | 157 (75.5) | 33 (18.7) | Ref | | |
| Vaginal delivery | 184 (47.9) | 42 (20.2) | 142 (86.7) | 0.06 | 0.04–0.10 | <0.001 |
| Cesarean section | 7 (1.8) | 6 (2.9) | 1 (0.6) | 1.26 | 0.15–10.82 | 0.83 |
| Vaginal birth after caesarean | 3 (0.8) | 3 (1.4) | 0 (0.0) | 1 | - | - |
| Gestational age | | | | | | |
| <34 weeks | 3 (0.8) | 3 (1.4) | 0 (0.0) | - | | |
| 34–37 weeks | 32 (8.3) | 13 (6.3) | 19 (10.8) | Ref | | |
| ≥37 weeks | 346 (90.1) | 191 (91.8) | 155 (88.1) | 1.80 | 0.86–3.76 | 0.12 |
| Unknown | 3 (0.8) | 1 (0.5) | 2 (1.1) | 0.81 | 0.06–8.92 | 0.81 |
| EFW (g) (mean±SD) | 3,026.6±373.6 | 3,026.6±372.8 | 3,026.8±375.6 | 1.00 | 0.99–1.00 | 1.00 |
| Gestational diabetes | 85 (22.1) | 40 (19.2) | 45 (25.6) | 0.69 | 0.43–1.12 | 0.14 |
| Premature rupture of membranes | 72 (18.8) | 43 (20.7) | 29 (16.5) | 1.32 | 0.78–2.22 | 0.30 |
| Group B Streptococcus (GBS) positive status | 33 (8.6) | 18 (8.7) | 15 (8.5) | 1.02 | 0.50–2.08 | 0.96 |
| Gestational hypertension | 11 (2.9) | 9 (4.3) | 2 (1.1) | 3.93 | 0.84–18.46 | 0.08 |
| Intrauterine growth restriction (IUGR) | 9 (2.3) | 6 (2.9) | 3 (1.7) | 1.71 | 0.42–6.95 | 0.45 |
| Labor induction | 37 (9.6) | 21 (10.1) | 16 (9.1) | 1.12 | 0.57–2.23 | 0.74 |
| Epidural analgesia | 229 (59.6) | 134 (64.4) | 95 (54.0) | 1.54 | 1.02–2.33 | 0.04 |
| Oxytocin use in labor | 78 (20.3) | 50 (24.0) | 28 (15.9) | 1.67 | 1.00–2.80 | 0.05 |
| Active labor duration (hours) (mean±SD) | 3.3±2.4 | 3.7±2.4 | 2.7±2.2 | 1.23 | 1.11–1.35 | <0.001 |
| Perineal length (cm) (mean±SD) | 4.0±0.7 | 4.0±0.8 | 3.9±0.5 | 1.44 | 1.05–1.98 | 0.02 |
| Fetal heart rate monitoring | | | | | | |
| Category I | 229 (59.6) | 110 (52.9) | 119 (67.6) | 0.52 | 0.34–0.80 | 0.003 |
| Category II | 152 (39.6) | 97 (46,6) | 55 (31.3) | Ref | | |
| Not monitored | 3 (0.8) | 1 (0.5) | 2 (1.1) | 0.28 | 0.03–3.20 | 0.31 |
| Total vaginal exams (mean±SD) | 7.2±2.9 | 7.7±2.8 | 6.6±2.8 | 1.14 | 1.06–1.23 | <0.001 |
| Duration of the second stage of labor (minutes) (mean±SD) | 34.5±35.6 | 43.4±39.0 | 23.9±27.7 | 1.02 | 1.01–1.03 | <0.001 |
| Birth attendants | | | | | | |
| Midwife | 122 (31.8) | 48 (23.1) | 74 (42.1) | Ref | | |
| Attending doctor | 120 (31.3) | 73 (35.1) | 47 (26.7) | 2.39 | 1.43–4.01 | 0.001 |
| Private doctor | 115 (29.9) | 75 (36.1) | 40 (22.7) | 2.89 | 1.70–4.90 | <0.001 |
| Trainee | 27 (7.0) | 12 (5.8) | 15 (8.5) | 1.23 | 0.53–2.86 | 0.63 |
| Delivery method | | | | | | |
| Spontaneous vaginal delivery | 362 (94.3) | 186 (89.42) | 176 (100.0) | 1 | - | - |
| Vacuum delivery | 16 (4.2) | 16 (7.7) | 0 (0.0) | - | - | - |
| Forceps delivery | 6 (1.5) | 6 (2.9) | 0 (0.0) | - | - | - |
| Degree of perineal injury | | | | | | |
| No injury | 35 (9.1) | 0 (0.0) | 35 (19.9) | - | | |
| First-degree tear | 124 (32.3) | 5 (2.4) | 119 (67.6) | Ref | | |
| Second-degree tear | 225 (58.6) | 203 (97.6) | 22 (12.5) | 219.61 | 81.03–595.20 | <0.001 |
| Total blood loss | | | | | | |
| ≤200 mL | 299 (77.9) | 144 (69.2) | 155 (88.1) | Ref | | |
| 200–500 mL | 79 (20.6) | 59 (28.4) | 20 (11.4) | 3.18 | 1.82–5.53 | <0.001 |
| ≥500 mL | 6 (1.5) | 5 (2.4) | 1 (0.5) | 5.38 | 0.62–46.62 | 0.13 |
| Pain score (Wong-Baker Faces Pain Rating Scale) 24 hours postpartum | 1.6±0.9 | 1.8±0.9 | 1.2±0.8 | 2.19 | 1.69–2.85 | <0.001 |
| Need for additional pain medication in postpartum departments | 86 (22.4) | 61 (29.3) | 25 (14.2) | 2.51 | 1.49–4.21 | 0.001 |
| Perineal condition in postpartum departments | | | | | | |
| Good recovery | 287 (74.7) | 134 (64.4) | 153 (86.9) | Ref | | |
| Perineal swelling | 89 (23.2) | 67 (32.2) | 22 (12.5) | 3.48 | 2.04–5.93 | <0.001 |
| Infection | 6 (1.5) | 5 (2.4) | 1 (0.6) | 5.71 | 0.66–49.48 | 0.11 |
| Wound dehiscence | 2 (0.5) | 2 (1.0) | 0 (0.0) | - | - | - |
| Length of hospital stay since delivery (days) | 2.4±0.9 | 2.5±1.0 | 2.4±0.8 | 1.22 | 0.96–1.55 | 0.11 |
| Apgar score 1 min≥7 | 375 (97.7) | 201 (96.6) | 174 (98.9) | 0.33 | 0.07–1.61 | 0.17 |
| Apgar score 5 min≥7 | 382 (99.5) | 206 (99.0) | 176 (100.0) | - | - | - |
| Birth weight (g) | 3,052.8±367.6 | 3,030.9±365.1 | 3,078.8±369.9 | 1.00 | 0.99–1.00 | 0.20 |
| Head circumference | 32±1.6 | 32.1±1.7 | 31.9±1.6 | 1.09 | 0.96–1.23 | 0.21 |
| Neonatal admission | 27 (7.0) | 17 (8.17) | 10 (5.7) | 1.48 | 0.66–3.32 | 0.34 |