Abstract
BACKGROUND: To identify factors related to reproductive history and weight change associated with first incident fracture in middle-aged women. METHODS: In total, 18,326 women from the Malmö Diet and Cancer study were included in this prospective population-based cohort study. Participants were included 1991-1996 and followed to 2016. Using data from the National Patient Registry, linked with every participants' unique personal identification number, any first fracture affecting spine, thoracic cage, upper and lower extremities was identified. The association of baseline factors with incident fracture risk was analyzed using Cox regression models. RESULTS: For participating women, median age 56.0 years, the multivariable Cox regression analysis observed that early menopause (40-44 years) (hazard ratio (HR) 1.14, 95% confidence interval (CI) 1.03-1.27) but not premature menopause < 40 years (HR 1.06, 95% CI 0.91-1.24) was associated with future fracture risk. Self-reported weight loss since age 20 was also associated with future fracture risk (HR 1.39, 95% CI 1.17-1.65) whereas a daily alcohol consumption in the third quartile (5.36-11.42 g/day) compared to the lowest quartile (0-0.80 g/day) was associated with decreased future fracture risk (HR 0.88, 95% CI 0.81-0.96). The multivariable Cox regression analysis also observed that increasing age and weight at baseline, current smoking, a positive history of previous fracture and family history of fractures were associated with increased fracture risk whereas an increasing BMI was associated with a decreased fracture risk. No association to parity or period of lactation was observed nor ever-use of oral contraceptives and menopausal hormone therapy. CONCLUSION: This study shows that early menopause between 40 to 45 years and self-reported weight loss since age of 20 are relevant factors associated with increased fracture risk in middle-aged women. These factors were independent of traditional predictors of fracture risk among women and may be considered in preventive initiatives. TRIAL REGISTRATION: Clinicaltrials.gov with identifier: NCT04151732, since Nov 5th 2018.