Table 4 Prevalence of chronic LBP by age at first and last childbirths, in women with at least two childbirths
Total number of women in category | Number of women with chronic LBP (%) | PR (95% CI) with adjustment for age, number of children, and age at first or last childbirth | PR (95% CI) with additional adjustmenta | |
|---|---|---|---|---|
Number of women included in the analysis | 20,584 | 18,384 | ||
Age at first childbirth (years) | ||||
≤ 19 | 4020 | 1397 (34.8) | 1.52 (1.41–1.65) | 1.36 (1.25–1.49) |
20–24 | 11,099 | 3278 (29.5) | 1.27 (1.19–1.35) | 1.18 (1.10–1.27) |
25–29 | 4560 | 1057 (23.2) | 1.00 (reference) | 1.00 (reference) |
30–34 | 772 | 179 (23.2) | 0.98 (0.85–1.12) | 1.04 (0.89–1.20) |
≥ 35 | 133 | 41 (30.8) | 1.25 (0.95–1.63) | 1.23 (0.91–1.66) |
P for categorical effect | < 0.001 | < 0.001 | ||
P for linear trend | < 0.001 | < 0.001 | ||
P for quadratic effect | < 0.001 | < 0.001 | ||
Age at last childbirth (years) | ||||
≤ 24 | 3082 | 956 (31.0) | 1.04 (0.96–1.12) | 1.03 (0.94–1.11) |
25–29 | 7736 | 2215 (28.6) | 1.00 (0.95–1.06) | 1.01 (0.95–1.07) |
30–34 | 6445 | 1798 (27.9) | 1.00 (reference) | 1.00 (reference) |
35–39 | 2843 | 847 (29.8) | 1.03 (0.96–1.11) | 1.05 (0.97–1.14) |
≥ 40 | 478 | 136 (28.5) | 0.96 (0.82–1.12) | 0.98 (0.82–1.17) |
P for categorical effect | 0.66 | 0.73 | ||
P for linear trend | 0.46 | 0.74 | ||
P for quadratic effect | 0.96 | 0.82 | ||