Association between reproductive history and chronic low back pain in the US women: a cross-sectional study.

BACKGROUND: Low back pain (LBP) is more prevalent in women, particularly peripartum, suggesting a link between reproductive history and chronic LBP (CLBP). Nationally representative evidence on this association is limited. METHODS: We conducted a cross-sectional study using NHANES 1999-2004 and 2009-2010 data. Weighted multivariable logistic regression examined associations between reproductive factors and CLBP. Restricted cubic splines assessed dose-response relationships. Subgroup and sensitivity analyses ensured robustness; multiple imputations addressed missing data. RESULTS: Women with CLBP had a significantly younger age at first live birth (22.01 vs. 23.05 years, P < 0.001) and elevated gravidity and parity. In fully adjusted models, both gravidity (odds ratio (OR) = 1.08; 95% confidence interval (CI) = 1.05-1.10) and parity (OR = 1.07; 95% CI = 1.04-1.11) were positively associated with CLBP, while older age at first (OR = 0.96; 95% CI = 0.94-0.97) and last live birth (OR = 0.97; 95% CI = 0.95-0.98) were associated with lower odds of CLBP. The highest odds were observed in women with a history of pregnancy but no live birth (OR = 2.33; 95% CI = 1.71-3.16). Birth at age ≤16 years was associated with 66% higher odds of CLBP (OR = 1.66; 95% CI = 1.26-2.18). CONCLUSIONS: First live birth, higher gravidity and parity, earlier last parity, and pregnancy without live birth are independently associated with a higher CLBP prevalence in women. Integrating reproductive history into pain-related clinical assessment and preventive care may be beneficial for targeted CLBP screening and prevention.