Grand multiparity associations with low bone mineral density and degraded trabecular bone pattern.

Introduction: Pregnancy is associated with changes in bone remodeling and calcium metabolism, which may increase the risk of fragility fracture after menopause. We hypothesized that in postmenopausal women, with history of grand multiparity, the magnitude of trabecular bone deterioration is associated with number of deliveries.

Methods: 1217 women aged 69.2 ± 6.4 years, from the Bushehr Elderly Health (BEH) program were recruited. The areal bone mineral density (aBMD) of the lumbar spine and femoral neck and trabecular bone score (TBS) of 916 postmenopausal women, with grand multiparity defined as more than 4 deliveries, were compared with those of 301 postmenopausal women with 4 or fewer deliveries. The association of multiparity with aBMDs and TBS were evaluated after adjustment for possible confounders including age, years since menopause, body mass index, and other relevant parameters.

Results: The aBMD of femoral neck (0.583 ± 0.110 vs. 0.603 ± 0.113 g/cm), lumbar spine (0.805 ± 0.144 vs. 0.829 ± 0.140 g/cm) and TBS (1.234 ± 0.086 vs. 1.260 ± 0.089) were significantly lower in women with history of grand multiparity than others. In the multiple regression analysis, after adjusting for confounders, the negative association did persist for lumbar spine aBMD (beta = -0.02, value = 0.01), and the TBS (beta = -0.01, p value = 0.03), not for femoral neck aBMD.

Conclusion: We infer that grand multiparity have deleterious effects on the aBMD and the trabecular pattern of the lumbar spine.