Table 4

Relative risk ratio (RRR) of overall spinal pain according to potential risk factors among the 46,726 children participated in the 11-year follow-up in the Danish National Birth Cohort

CharacteristicsOverall spinal pain
ModelabModel 2ac
Moderate pain
RRR (95% CI)
Severe pain
RRR (95% CI)
Moderate pain
RRR (95% CI)
Severe pain
RRR (95% CI)
Sex, age
 Boys, 11 yearsRef.Ref.Ref.Ref.
 Boys, 12 years1.12 (1.03–1.21)1.16 (1.03–1.31)1.12 (1.03–1.21)1.15 (1.02–1.30)
 Boys, 13+ years1.41 (1.18–1.69)1.29 (0.98–1.70)1.41 (1.17–1.69)1.26 (0.96–1.66)
 Girls, 11 years1.15 (1.10–1.20)1.46 (1.37–1.56)1.14 (1.09–1.19)1.44 (1.35–1.54)
 Girls, 12 years1.41 (1.31–1.53)2.39 (2.16–2.64)1.41 (1.30–1.52)2.34 (2.12–2.59)
 Girls, 13+ years1.49 (1.23–1.80)3.47 (2.83–4.26)1.48(1.23–1.79)3.40 (2.77–4.18)
Sibling position
 Biological full siblingsRef.Ref.Ref.Ref.
 Biological only child1.18 (1.10–1.25)1.35 (1.24–1.47)1.12 (1.05–1.20)1.18 (1.08–1.30)
Family type
 Child lives with both parentsRef.Ref.Ref.Ref.
 Child not living with (both) parentsd1.25 (1.19–1.31)1.57 (1.47–1.68)1.18 (1.12–1.25)1.39 (1.29–1.50)
Maternal educational level
 HighRef.Ref.Ref.Ref.
 Medium1.02 (0.98–1.07)1.18 (1.13–1.27)0.99 (0.94–1.03)1.11 (1.05–1.19)
 Low1.08 (1.00–1.20)1.62 (1.45–1.82)1.01 (0.92–1.11)1.37 (1.21–1.55)
Equivalised household income
 4th quartile (highest)Ref.Ref.Ref.Ref.
 3rd quartile1.06 (1.01–1.12)1.10 (1.02–1.18)1.05 (1.00–1.11)1.06 (0.98–1.14)
 2nd quartile1.11 (1.05–1.17)1.23 (1.14–1.33)1.07 (1.01–1.13)1.09 (1.00–1.18)
 1st quartile (lowest)1.19 (1.10–1.27)1.55 (1.46–1.70)1.10 (1.02–1.18)1.23 (1.11–1.36)
Maternal age at childbirth
 ≤ 25 yearsRef.Ref.Ref.Ref.
 26–30 years0.92 (0.86–0.98)0.84 (0.77–0.92)0.96 (0.89–1.02)0.95 (0.86–1.04)
 31–35 years0.91 (0.85–0.98)0.81 (0.74–0.89)0.95 (0.89–1.02)0.91 (0.83–1.01)
 > 35 years0.87 (0.80–0.95)0.78 (0.69–0.88)0.90 (0.83–0.98)0.87 (0.77–0.98)
aReference category: not having reported moderate or severe spinal pain (no pain)

bCrude model

cAdjusted for additional variables in the model, as well as the interaction between child’s age and sex (P < 0.001)

dParents not living together due to divorce, separation, they never lived together, or only one parent alive