Abstract Objective Reproductive disorders, such as premature ovarian insufficiency (POI) and polycystic ovary syndrome (PCOS), are associated with hormonal and metabolic changes, which might lead to changes in bone mineral density (BMD). On the one hand women with POI enter menopause too early and have less estrogen exposure rendering them more prone to develop low BMD. On the other hand women with PCOS, who often have a delayed menopause and therefore experience longer estrogen exposure, may have an increased BMD. A third reproductive disorder, preeclampsia (PE) does not seem to affect BMD or menopausal age. The effect of these reproductive disorders, with different menopausal ages, on BMD could be most evident in middle-aged women. We hypothesized that the duration of estrogen exposure is a key factor in BMD. Materials and methods In this cross-sectional study we compared the BMD of 258 women with a history of PE as a reference group (age 46.0; 40% postmenopausal) to 90 women with POI (age 48.1; 100% postmenopausal) and 84 women with PCOS (age 48.3; 26% postmenopausal). BMD was measured using non-contrast coronary CT scans in three consecutive thoracic vertebrae (in the T7-T10 range). Secondary outcomes included T-scores, prevalence of osteoporosis and osteopenia and the comparison of measured BMD to predicted BMD, calculated by a formula based on age. We performed linear regression analysis to assess differences in BMD between groups, adjusted for age and BMI. Results Compared to women with a history of PE, women with POI had lower BMD (p<0.001) and women with PCOS had higher BMD (p=0.003). Prevalence of osteoporosis was higher in women with POI (12.2%) compared to PE (0.8%; P=0.002) and none of the women with PCOS fulfilled the criteria for osteoporosis. Prevalence of osteopenia was significantly higher in the POI group and lower in the PCOS group compared to the PE group (57.8%, 17.9% and 26.4% respectively; p<0.01). As expected, measured BMD of women with POI was significantly lower than the predicted BMD. On the contrary, the measured BMD of women with PCOS was significantly higher than the predicted BMD. Interestingly, the measured BMD of women with a history of PE was also higher than the predicted BMD. Conclusion Our results imply that prolonged estrogen exposure as in PCOS is associated with a higher BMD. A lower estrogen exposure associated with an early menopause in POI is associated with a lower BMD and osteoporosis. Patients with a history of PE could be seen as an intermediate group in terms of BMD and estrogen exposure, however, the measured BMD of women with a history of PE was higher than the predicted BMD. This study emphasizes the importance of adequate counseling on long term health issues when diagnosing a reproductive disorder. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.