Table 1 The CS rates of Robson Classification by residents and migrants (n = 40,621)
|  | Residents(n = 27,169) | Migrants(n = 13,452) | p a | p b, c | ||||
|---|---|---|---|---|---|---|---|---|
CS rate % | Rate of CSMR% | Rate of MICS% | CS rate % | Rate of CSMR % | Rate of MICS % | Â | Â | |
Modified Robson Ten-group Classification System | ||||||||
 1 Nulliparous women with a single cephalic pregnancy, at ≥37 weeks of gestation in spontaneous labour | 6.2 (558/8941) | 3.1 (279/8941) | 3.1 (279/8941) | 5.0 (236/4675) | 2.4 (112/4675) | 2.7 (124/4675) | 0.005 | 0.015 |
 2 Nulliparous women with a single cephalic pregnancy, at ≥37 weeks of gestation, who had labour induced | 19.5 (878/4501) | 11.2 (504/4501) | 8.3 (374/4501) | 20.8 (548/2630) | 11.1 (291/2630) | 9.8 (257/2630) | 0.176 | 0.110 |
 3 Multiparous women, without a uterine scar, with a single cephalic pregnancy at ≥37 weeks of gestation in spontaneous labour | 5.1 (61/1199) | 1.4 (17/1199) | 3.7 (44/1199) | 4.6 (43/939) | 1.6 (15/939) | 3.0 (28/939) | 0.588 | 0.648 |
 4 Multiparous women, without a uterine scar, with a single cephalic pregnancy at ≥37 weeks of gestation, who had labour induced | 7.4 (26/350) | 2.3 (8/350) | 5.1 (18/350) | 8.6 (24/278) | 1.4 (4/278) | 7.2 (20/278) | 0.580 | 0.431 |
 5 Multiparous women, with at least one previous uterine scar with a single cephalic pregnancy at ≥37 weeks of gestation | 98.2 (387/394) | 0 (0/394) | 98.2 (387/394) | 96.8 (240/248) | 0 (0/248) | 96.8 (240/248) | 0.237 | 0.286 |
 6 All women with a single non-cephalic pregnancy, with previous CS | 98.7 (1169/1184) | 0 (0/1184) | 98.7 (1169/1184) | 98.6 (562/570) | 0 (0/570) | 98.6 (562/570) | 0.814 | 0.825 |
 7 Nulliparous women with a single cephalic pregnancy, at ≥37 weeks of gestation, who had caesarean section before labourd | 100.0 (7419/7419) | 51.3 (3803/7419) | 48.7 (3616/48.9) | 100.0 (2373/2373) | 49.6 (1176/2373) | 50.4 (1197/2372) | – | 0.150 |
 8 Multiparous women, without a uterine scar, with a single cephalic pregnancy at ≥37 weeks of gestation, who had caesarean section before labour d | 100.0 (1295/1295) | 31.4 (407/1295) | 68.6 (888/1295) | 100.0 (716/716) | 30.2 (216/716) | 69.8 (500/716) | – | 0.580 |
 9 All women with multiple pregnancies including women with a uterine scar | 95.9 (662/690) | 31.2 (215/690) | 64.8 (447/690) | 93.7 (388/414) | 33.8 (140/414) | 59.9 (248/414) | 0.097 | 0.125 |
 10 All women with a single cephalic pregnancy at < 37 weeks gestation, including women with previous CS | 41.6 (498/1196) | 17.4 (208/1196) | 24.2 (290/1196) | 39.4 (240/609) | 16.6 (101/609) | 22.8 (139/607) | 0.384 | 0.658 |