Table 2. Perinatal outcomes after induction of labour compared with expectant management (primary analysis).
| Outcome | Week of gestation induction was performed | Induction group | Expectant management group (delivery beyond week of induction) | Univariate analysis | Multivariable analysis | ||
|---|---|---|---|---|---|---|---|
| n (%) | n (%) | RR | 95% CI | adjRR | 95% CI | ||
| In-hospital perinatal death | 39 | 3 (0.08) | 123 (0.22) | 0.36 | (0.12 to 1.15) | 0.37 | (0.12 to 1.15) |
| 40 | 5 (0.08) | 74 (0.26) | 0.32 | (0.13 to 0.80)* | 0.33 | (0.13 to 0.80)* | |
| 41 | 5 (0.07) | 19 (0.30) | 0.25 | (0.10 to 0.62)** | 0.24 | (0.09 to 0.65)** | |
| Stillbirth | 39 | 2 (0.05) | 99 (0.18) | 0.30 | (0.07 to 1.23) | 0.31 | (0.08 to 1.26) |
| 40 | 3 (0.05) | 61 (0.22) | 0.23 | (0.07 to 0.75)* | 0.25 | (0.08 to 0.79)* | |
| 41 | 3 (0.04) | 15 (0.24) | 0.18 | (0.06 to 0.58)** | 0.18 | (0.05 to 0.65)** | |
| Birth injury | 39 | 15 (0.40) | 249 (0.45) | 0.90 | (0.54 to 1.52) | 0.87 | (0.52 to 1.46) |
| 40 | 28 (0.47) | 137 (0.49) | 0.98 | (0.65 to 1.46) | 0.96 | (0.63 to 1.46) | |
| 41 | 24 (0.33) | 41 (0.65) | 0.63 | (0.41 to 0.97)* | 0.47 | (0.29 to 0.78)** | |
| Shoulder dystocia | 39 | 42 (1.13) | 602 (1.08) | 1.05 | (0.77 to 1.43) | 0.87 | (0.64 to 1.19) |
| 40 | 66 (1.12) | 308 (1.09) | 1.02 | (0.78 to 1.33) | 0.85 | (0.65 to 1.11) | |
| 41 | 64 (0.88) | 75 (1.20) | 0.76 | (0.58 to 1.00) | 0.68 | (0.49 to 0.94)* | |
| Hypoxia in laboura | 39 | 219 (5.90) | 4,310 (7.73) | 0.76 | (0.67 to 0.87)*** | 0.74 | (0.65 to 0.85)*** |
| 40 | 492 (8.33) | 2,367 (8.40) | 0.99 | (0.90 to 1.09) | 0.98 | (0.89 to 1.08) | |
| 41 | 645 (8.89) | 560 (8.92) | 1.08 | (0.99 to 1.17) | 1.02 | (0.91 to 1.13) | |
| Meconium aspiration syndrome | 39 | 6 (0.16) | 414 (0.74) | 0.22 | (0.10 to 0.49)*** | 0.22 | (0.10 to 0.49)*** |
| 40 | 26 (0.44) | 242 (0.86) | 0.51 | (0.34 to 0.77)** | 0.52 | (0.35 to 0.78)** | |
| 41 | 41 (0.57) | 62 (0.99) | 0.67 | (0.48 to 0.93)* | 0.57 | (0.39 to 0.83)** | |
| Seizuresa | 39 | 12 (0.32) | 143 (0.26) | 1.26 | (0.70 to 2.27) | 1.14 | (0.62 to 2.10) |
| 40 | 12 (0.20) | 78 (0.28) | 0.73 | (0.40 to 1.35) | 0.67 | (0.36 to 1.24) | |
| 41 | 15 (0.21) | 23 (0.37) | 0.74 | (0.43 to 1.29) | 0.50 | (0.26 to 0.99)* | |
| Neonatal readmission within 28 days of birtha | 39 | 119 (3.20) | 1,534 (2.75) | 1.16 | (0.97 to 1.30) | 1.16 | (0.96 to 1.30) |
| 40 | 192 (3.25) | 709 (2.52) | 1.29 | (1.04 to 1.50)** | 1.30 | (1.03 to 1.50)** | |
| 41 | 176 (2.43) | 160 (2.55) | 0.90 | (0.76 to 1.00) | 0.95 | (0.76 to 1.10) | |
| Emergency caesarean sectiona,b,c | 39 | 1,301 (35.02) | 15,992 (28.67) | 1.22 | (1.17 to 1.28)*** | 1.04 | (0.99 to 1.09) |
| 40 | 2,312 (38.94) | 9,409 (33.38) | 1.17 | (1.13 to 1.22)*** | 1.05 | (1.01 to 1.09)* | |
| 41 | 2,994 (41.27) | 2,636 (42.00) | 1.26 | (1.23 to 1.31)*** | 0.94 | (0.90 to 0.97)** | |
| Instrumental deliverya,b,c | 39 | 994 (26.76) | 15,414 (27.63) | 0.97 | (0.92 to 1.02) | 1.04 | (0.98 to 1.10) |
| 40 | 1,647 (27.88) | 7,894 (28.00) | 1.00 | (0.95 to 1.04) | 1.06 | (1.01 to 1.11)* | |
| 41 | 2,024 (27.90) | 1,699 (27.07) | 1.00 | (0.96 to 1.04) | 1.06 | (1.00 to 1.12) | |
| 3rd or 4th degree tearsa | 39 | 121 (3.26) | 1,945 (3.49) | 0.93 | (0.78 to 1.12) | 0.97 | (0.81 to 1.17) |
| 40 | 183 (3.10) | 973 (3.45) | 0.90 | (0.77 to 1.05) | 0.93 | (0.79 to 1.10) | |
| 41 | 216 (2.98) | 208 (3.31) | 0.85 | (0.74 to 0.98) | 0.91 | (0.75 to 1.10) | |
| Maternal readmission within 28 days of giving birtha | 39 | 114 (3.07) | 1,120 (2.01) | 1.52 | (1.26 to 1.80)*** | 1.38 | (1.13 to 1.60)** |
| 40 | 146 (2.47) | 543 (1.93) | 1.28 | (1.07 to 1.50)** | 1.16 | (0.96 to 1.30) | |
| 41 | 156 (2.15) | 118 (1.88) | 1.08 | (0.91 to 1.00) | 1.06 | (0.83 to 1.30) | |
*P < 0.05
** P < 0.01
*** P < 0.001. Estimates were adjusted for pregnancy-related conditions when these were found to have significant coefficient: apreeclampsia/pregnancy-induced hypertension/edema in pregnancy
bgestational diabetes
cabnormal fluid volume (oligohydramnios or polyhydramnios).
Abbreviations: adjRR, adjusted risk ratio; RR, risk ratio (unadjusted).