The impact of reproductive and menstrual history on bone mineral density in Chinese women.

Low bone mineral density (BMD) is an important risk factor for osteoporotic fractures. The impact of gynecological history on BMD is of great concern, but the results are largely inconsistent. In this study, we investigated the association of gynecological history with BMD in 214 postmenopausal women (60.4 +/- 5.7 yr), as well as with peak bone density (PBD) in 428 premenopausal women (30.8 +/- 5.3 yr) from Shanghai City in China. BMD was measured at lumbar spine (L1-4) and total hip by dual energy X-ray absorptiometry. Raw BMD values were adjusted by age, age2, height, and weight. In the postmenopausal group, more parity had significantly detrimental effects on BMD at both the spine and hip (p < 0.01). The age of the first delivery, the duration of lactation, and the age at menarche did not show significant impacts on BMD (p > 0.05). More years since menopause only had marginally significant decreasing effects at the spine (p = 0.09), but not at the hip (p > 0.10). In the premenopausal group, none of the three reproductive factors had significant impact on PBD (p > 0.05); the age of menarche inversely affected PBD at both the spine (p < 0.01) and hip (p < 0.05). Our results suggest that some gynecological events might influence BMD variation in healthy Chinese women.