| Cerclage Height (mm) | Delivery <34 weeks RR(95%CI) | Delivery<37weeks RR(95%CI) |
|---|---|---|
| <20 | 1.14*(1.03 – 1.26) | 1.15*(1.03 – 1.29) |
| <15 | 1.42*(1.09 –1.85) | 1.58*(1.20 – 2.08) |
| <10 | 1.65(0.92–2.97) | 1.94*(1.07 – 3.51) |
| Cerclage Height (%) | ||
| <80 | 0.98(0.83 – 1.16) | 0.97(0.84 – 1.13) |
| <70 | 1.05(0.86 – 1.29) | 1.05(0.86 – 1.28) |
| <60 | 1.39*(1.07 – 1.81) | 1.39*(1.06 – 1.82) |
| <50 | 1.72*(1.11 – 2.68) | 2.10*(1.32 – 3.35) |
↵* p<0.05