Table 3 Prevalence of chronic LBP by age at childbirth, in women with one childbirth only
Total number of women in category | Number of women with chronic LBP (%) | PR (95% CI) with adjustment for age only | PR (95% CI) with additional adjustmenta | |
|---|---|---|---|---|
Total number of women in the analysis | 3143 | 2893 | ||
Age at childbirth (years) | ||||
≤ 19 | 420 | 119 (28.3) | 1.50 (1.23–1.83) | 1.42 (1.16–1.74) |
20–24 | 1257 | 288 (22.9) | 1.22 (1.03–1.43) | 1.14 (0.96–1.35) |
25–29 | 927 | 182 (19.6) | 1.00 (reference) | 1.00 (reference) |
30–34 | 361 | 98 (27.1) | 1.18 (0.96–1.47) | 1.17 (0.94–1.45) |
≥ 35 | 178 | 46 (25.8) | 1.07 (0.80–1.42) | 1.14 (0.86–1.52) |
P for categorical effect | 0.002 | 0.027 | ||
P for linear trend | 0.005 | 0.12 | ||
P for quadratic effect | 0.028 | 0.040 | ||