Table 3. Trends in vaginal birth after caesarean section by maternal age, number of previous caesarean sections and hospital level, China, 2012–2016.
| Characteristic | Vaginal birth after caesarean section |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| cRR (95% CI) |
Pa | aRR (95% CI) | Pa | |||||||||
| 2012 | 2013 | 2014 | 2015 | 2016 | 2012 | 2013 | 2014 | 2015 | 2016 | |||
| Maternal age, yearsb | ||||||||||||
| < 20 | 1.00 | 0.97 (0.73–1.27) | 0.87 (0.66–1.13) | 0.91 (0.71–1.17) | 1.15 (0.90–1.47) | 0.0000 | 1.00 | 1.05 (0.82–1.36) | 0.91 (0.71–1.16) | 0.95 (0.75–1.21) | 1.17 (0.94–1.47) | 0.0046 |
| 20–24 | 1.00 | 0.97 (0.89–1.05) | 0.99 (0.92–1.07) | 1.11 (1.02–1.22) | 1.18 (1.07–1.29) | 1.00 | 0.95 (0.88–1.03) | 0.99 (0.92–1.07) | 1.10 (1.01–1.19) | 1.15 (1.05–1.26) | ||
| 25–29 | 1.00 | 0.96 (0.91–1.01) | 0.93 (0.87–1.00) | 1.00 (0.92–1.09) | 1.04 (0.95–1.13) | 1.00 | 0.95 (0.90–1.00) | 0.96 (0.90–1.02) | 1.04 (0.96–1.13) | 1.12 (1.03–1.21) | ||
| 30–34 | 1.00 | 0.97 (0.91–1.03) | 0.95 (0.88–1.02) | 1.04 (0.95–1.13) | 1.06 (0.97–1.16) | 1.00 | 0.98 (0.92–1.03) | 1.01 (0.95–1.08) | 1.13 (1.04–1.22) | 1.20 (1.11–1.29) | ||
| ≥ 35 | 1.00 | 0.90 (0.83–0.97) | 0.88 (0.81–0.95) | 0.94 (0.85–1.03) | 0.93 (0.85–1.02) | 1.00 | 0.92 (0.85–0.98) | 0.96 (0.89–1.04) | 1.07 (0.98–1.16) | 1.11 (1.02–1.21) | ||
| No. of previous caesarean sectionsc | ||||||||||||
| 1 | 1.00 | 0.95 (0.92–0.99) | 0.94 (0.89–0.99) | 1.00 (0.94–1.07) | 1.02 (0.95–1.10) | 0.0000 | 1.00 | 0.96 (0.92–1.00) | 1.00 (0.95–1.05) | 1.09 (1.02–1.16) | 1.17 (1.09–1.25) | 0.0000 |
| 2 | 1.00 | 0.84 (0.71–1.00) | 0.70 (0.58–0.85) | 0.69 (0.58–0.83) | 0.65 (0.55–0.77) | 1.00 | 0.87 (0.75–1.02) | 0.78 (0.66–0.93) | 0.79 (0.66–0.93) | 0.74 (0.63–0.87) | ||
| ≥ 3 | 1.00 | 0.78 (0.36–1.70) | 0.83 (0.38–1.79) | 0.75 (0.34–1.64) | 0.41 (0.21–0.81) | 1.00 | 0.68 (0.32–1.44) | 0.76 (0.36–1.59) | 0.76 (0.35–1.62) | 0.47 (0.25–0.88) | ||
| Hospital leveld | ||||||||||||
| Level 1 | 1.00 | 0.83 (0.74–0.93) | 0.79 (0.68–0.93) | 0.84 (0.70–1.02) | 0.90 (0.71–1.14) | 0.0000 | 1.00 | 0.81 (0.72–0.92) | 0.79 (0.68–0.91) | 0.84 (0.70–1.02) | 0.91 (0.73–1.13) | 0.0000 |
| Level 2 | 1.00 | 0.96 (0.91–1.01) | 0.92 (0.86–0.99) | 0.97 (0.90–1.05) | 0.94 (0.86–1.02) | 1.00 | 0.98 (0.93–1.03) | 0.98 (0.92–1.04) | 1.05 (0.98–1.14) | 1.08 (1.00–1.17) | ||
| Level 3 | 1.00 | 0.95 (0.90–1.01) | 0.99 (0.89–1.09) | 1.09 (0.96–1.25) | 1.15 (1.03–1.30) | 1.00 | 0.93 (0.88–0.99) | 1.02 (0.94–1.11) | 1.16 (1.04–1.29) | 1.28 (1.16–1.41) | ||
| Unknown | 1.00 | 0.98 (0.87–1.10) | 1.06 (0.92–1.22) | 1.06 (0.89–1.27) | 1.28 (0.89–1.84) | 1.00 | 0.92 (0.84–1.01) | 1.01 (0.92–1.10) | 0.97 (0.85–1.12) | 1.26 (0.93–1.71) | ||
| Total | 1.00 | 0.95 (0.91–0.98) | 0.93 (0.88–0.98) | 0.98 (0.92–1.05) | 1.00 (0.93–1.07) | NA | 1.00 | 0.95 (0.92–0.99) | 0.98 (0.93–1.03) | 1.07 (1.00–1.14) | 1.14 (1.07–1.21) | NA |
aRR: adjusted relative risk; CI: confidence interval; cRR: crude relative risk; NA: not applicable.
a We calculated P-value for interactions between year and maternal age; year and number of previous caesarean sections; and year and hospital level.
b We did not adjust for maternal age in the age groups.
c We did not adjust for number of caesarean sections in previous pregnancy when calculating aRR for number of previous caesarean sections.
d We did not adjust for hospital level in the hospital-level group.