Table 1. Trial of labor after cesarean section (TOLAC) and TOLAC failure in low risk pregnancies by maternal characteristics and size of delivery unit, Norway 1989–2014.
Rate, relative risk (RR) and RR adjusted (ARR) for maternal age, origin, education, and delivery unit size.
| TOLAC | Failed TOLAC | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Determinant | N | n | % | RR | 95% CI | ARR | 95% CI | n | % | RR | 95% CI | ARR | 95% CI | ||||||
| Maternal age (years) | |||||||||||||||||||
| <25 | 2532 | 2052 | 81.0 | Reference = 1 | 297 | 14.5 | Reference = 1 | ||||||||||||
| 25–29 | 8278 | 6554 | 79.2 | 0.97 | 0.95 | 0.99 | 0.96 | 0.94 | 0.98 | 941 | 14.4 | 0.99 | 0.88 | 1.12 | 1.04 | 0.92 | 1.18 | ||
| 30–34 | 9383 | 7019 | 74.8 | 0.92 | 0.90 | 0.94 | 0.89 | 0.88 | 0.91 | 1166 | 16.6 | 1.15 | 1.02 | 1.29 | 1.24 | 1.10 | 1.41 | ||
| 35–39 | 3761 | 2512 | 66.8 | 0.82 | 0.80 | 0.84 | 0.80 | 0.78 | 0.82 | 499 | 19.9 | 1.37 | 1.20 | 1.57 | 1.49 | 1.30 | 1.70 | ||
| >39 | 691 | 322 | 46.6 | 0.57 | 0.53 | 0.62 | 0.57 | 0.53 | 0.62 | 91 | 28.3 | 1.95 | 1.59 | 2.39 | 2.08 | 1.69 | 2.56 | ||
| Maternal education (years) | |||||||||||||||||||
| <11 | 11713 | 8691 | 74.2 | Reference = 1 | 1477 | 17.0 | Reference = 1 | ||||||||||||
| 11–14 | 9882 | 7473 | 75.6 | 1.02 | 1.00 | 1.03 | 1.04 | 1.03 | 1.06 | 1140 | 15.3 | 0.90 | 0.84 | 0.96 | 0.93 | 0.86 | 1.00 | ||
| >14 | 2704 | 2020 | 74.7 | 1.00 | 0.97 | 1.02 | 1.04 | 1.02 | 1.07 | 327 | 16.2 | 0.95 | 0.85 | 1.06 | 0.95 | 0.85 | 1.07 | ||
| Missing | 346 | 275 | 79.5 | 50 | 18.2 | ||||||||||||||
| Maternal origin (country) | |||||||||||||||||||
| Norway | 20245 | 15245 | 75.3 | Reference = 1 | 2322 | 15.2 | Reference = 1 | ||||||||||||
| Europe | 1247 | 931 | 74.7 | 0.99 | 0.96 | 1.02 | 1.01 | 0.98 | 1.04 | 146 | 15.7 | 1.03 | 0.88 | 1.20 | 0.96 | 0.82 | 1.12 | ||
| North America | 130 | 101 | 77.7 | 1.03 | 0.94 | 1.13 | 1.03 | 0.95 | 1.13 | 13 | 12.9 | 0.85 | 0.51 | 1.41 | 0.85 | 0.51 | 1.41 | ||
| Latin America and the Caribbean | 187 | 112 | 59.9 | 0.80 | 0.71 | 0.90 | 0.83 | 0.74 | 0.93 | 31 | 27.7 | 1.82 | 1.34 | 2.46 | 1.67 | 1.24 | 2.26 | ||
| West Asia, South Asia, North Africa | 837 | 634 | 75.7 | 1.02 | 0.98 | 1.06 | 1.00 | 0.97 | 1.04 | 136 | 21.5 | 1.41 | 1.21 | 1.64 | 1.43 | 1.22 | 1.67 | ||
| Africa south of the Sahara | 511 | 410 | 80.2 | 1.07 | 1.03 | 1.12 | 1.07 | 1.03 | 1.11 | 153 | 37.3 | 2.45 | 2.15 | 2.79 | 2.30 | 2.01 | 2.64 | ||
| East Asia, South-East Asia | 468 | 293 | 62.6 | 0.85 | 0.79 | 0.91 | 0.87 | 0.81 | 0.93 | 72 | 24.6 | 1.61 | 1.32 | 1.98 | 1.47 | 1.20 | 1.80 | ||
| Oceania | 9 | 8 | 88.9 | 1 | 12.5 | ||||||||||||||
| Missing | 1011 | 725 | 71.7 | 121 | 16.5 | ||||||||||||||
| Size of unit (deliveries/year) | |||||||||||||||||||
| ≥3000 | 8687 | 6677 | 76.9 | Reference = 1 | 1030 | 15.4 | Reference = 1 | ||||||||||||
| 1500–2999 | 7332 | 5356 | 73.0 | 0.96 | 0.94 | 0.97 | 0.96 | 0.94 | 0.97 | 915 | 17.1 | 1.11 | 1.02 | 1.20 | 1.16 | 1.07 | 1.26 | ||
| 500–1499 | 5937 | 4445 | 74.9 | 0.98 | 0.96 | 1.00 | 0.96 | 0.95 | 0.98 | 731 | 16.4 | 1.07 | 0.98 | 1.16 | 1.20 | 1.10 | 1.32 | ||
| <500 | 2650 | 1942 | 73.3 | 0.96 | 0.93 | 0.98 | 0.95 | 0.92 | 0.97 | 318 | 16.4 | 1.06 | 0.95 | 1.19 | 1.22 | 1.09 | 1.37 | ||
| Missing/not hospital | 39 | 39 | 100 | 0 | 0 | ||||||||||||||
| Total | 24645 | 18459 | 74.9 | 2994 | 16.2 | ||||||||||||||