Pregnancy history is associated with lower odds of osteoporosis among Taiwanese women.
BACKGROUND Osteoporosis is a major public health concern worldwide. Although female reproductive factors have been suggested to influence bone health, their associations with osteoporosis remain inconclusive. OBJECTIVE This study aimed to investigate the associations between reproductive characteristics and the odds of osteoporosis in Taiwanese women. METHODS We conducted a cross-sectional analysis using data from women randomly selected from the Taiwan Biobank. Bone mineral density (BMD) status was classified into three categories according to the World Health Organization (WHO) criteria: normal BMD (T-score > - 1.0), osteopenia (- 2.5 < T-score ≤ - 1.0), and osteoporosis (T-score ≤ - 2.5). Univariable and multivariable logistic regression analyses were performed to assess the association between reproductive factors and the odds of BMD status. RESULTS Among the 4,854 participants, 3,107 (64.0%) were classified as having normal BMD, 1,374 (28.3%) as having osteopenia, and 373 (7.7%) as having osteoporosis. Univariate analysis showed that a history of pregnancy was associated with a higher odd of osteopenia (odds ratio [OR] = 1.946, 95% CI: 1.589-2.382, p < 0.001), osteoporosis (OR = 1.825, 95% CI: 1.288-2.586, p = 0.001), and low BMD level (T-score < -0.1) (OR = 1.919, 95% CI: 1.597-2.306, p < 0.001). After adjusting for known confounders, pregnancy history was associated with a lower odd of osteoporosis (adjusted OR = 0.644, 95% CI: 0.422-0.981, p = 0.041), but not significantly associated with the odds of osteopenia or low BMD level. CONCLUSIONS Pregnancy history was independently associated with lower odds of osteoporosis among Taiwanese women after adjustment for known confounding factors. However, given the cross-sectional nature of this study, causal relationships cannot be established. Future longitudinal studies are warranted to validate this finding.