Background: Osteoporosis is rapidly becoming a serious global issue, especially for women. This is particularly true for women in Iraq, where a lack of health beliefs towards osteoporosis in addition to a low awareness of the disease, leads to an increased burden of disease. Methods: This study obtained a balanced panel data set of the health beliefs (e.g., perceived susceptibility, perceived severity, perceived benefits, perceived barriers, cues to action, and perceived self-efficacy) and preventive behaviors for osteoporosis for 250 postmenopausal women in Iraq for a period of 12 months. To control for the unobserved individual heterogeneity, a Fixed-Effects (FE) panel time-series model was used. As part of the analysis, a number of diagnostic checks, including the Wooldridge test for autocorrelation, were performed. Results: The FE model demonstrated that perceived susceptibility (β = 0.34, p < 0.001), perceived severity (β = 0.28, p < 0.001), and self-efficacy (β = 0.45, p < 0.001) significantly enhance preventive behaviors over time, while perceived barriers (β = -0.22, p = 0.015) reduce them. Conclusion: Long-term changes in health beliefs translate directly to improvements in osteoporosis prevention. Fixed-effects modeling offers an excellent framework for analyzing these trends in behavioral changes in women in Iraq.