OBJECTIVE: To investigate the impact of multiple pregnancies on postmenopausal bone mineral density (BMD). STUDY DESIGN: BMD at the femoral neck (FN) and lumbar spine (LS) was measured by dual energy X-ray absorptiometry (DXA) method. Diagnosis of osteoporosis (OP) was confirmed by World Health Organization criteria. Women were stratified according to number of parity as < 3, 4-7, and > 7 parity groups as well as in age groups of < 65 and 65 in age groups of < 65 and > or = 65 years. BMD values and frequency of OP were compared across the groups according to age. Multiple logistic regression analysis with calculation of adjusted odds ratio (OR) was used for association. RESULTS: A total of 264 women with mean age of 63 +/- 8.7 and mean menopausal duration of 15.8 +/- 10.2 years were studied. LS-OP and FN-OP were observed in 28% and 58.3% of women, respectively. There were significant differences in BMD values across different parity groups at both sites of LS and FN (p = 0.011 and p = 0.036, respectively). Parity 4-7 (vs. < or = 3) increased BMD nonsignificantly, but > 7 significantly decreased LS-BMD and FN-BMD as compared with 0-7 parity (p = 0.006 and p = 0.009, respectively). Parity > 7 increased the risk of LS-OP by OR = 1.81 (95% CI 1.03-3.1, p = 0.037) and FN-OP by OR = 1.67 (95% CI 0.97-2.8, p = 0.063). In addition, women with high parity had lower BMD decline at LS and FN by age (> or = 65 vs. < 65 years) by 1.3% (p = 0.77) and -10.1% (p = 0.009) as compared with 0-7 parity group by -9.5% (p = 0.001) and -15% (p = 0.0001), respectively. CONCLUSION: Parity > 7 is associated with spinal trabecular bone loss in younger postmenopausal women as well as an osteoprotective effect against age-related bone loss, which counteracts the early negative effect. Therefore, parity should not be considered as a risk factor for postmenopausal osteoporosis.
OBJECTIVE: To investigate the impact of multiple pregnancies on postmenopausal bone mineral density (BMD). STUDY DESIGN: BMD at the femoral neck (FN) and lumbar spine (LS) was measured by dual energy X-ray absorptiometry (DXA) method. Diagnosis of osteoporosis (OP) was confirmed by World Health Organization criteria. Women were stratified according to number of parity as < 3, 4-7, and > 7 parity groups as well as in age groups of < 65 and 65 in age groups of < 65 and > or = 65 years. BMD values and frequency of OP were compared across the groups according to age. Multiple logistic regression analysis with calculation of adjusted odds ratio (OR) was used for association. RESULTS: A total of 264 women with mean age of 63 +/- 8.7 and mean menopausal duration of 15.8 +/- 10.2 years were studied. LS-OP and FN-OP were observed in 28% and 58.3% of women, respectively. There were significant differences in BMD values across different parity groups at both sites of LS and FN (p = 0.011 and p = 0.036, respectively). Parity 4-7 (vs. < or = 3) increased BMD nonsignificantly, but > 7 significantly decreased LS-BMD and FN-BMD as compared with 0-7 parity (p = 0.006 and p = 0.009, respectively). Parity > 7 increased the risk of LS-OP by OR = 1.81 (95% CI 1.03-3.1, p = 0.037) and FN-OP by OR = 1.67 (95% CI 0.97-2.8, p = 0.063). In addition, women with high parity had lower BMD decline at LS and FN by age (> or = 65 vs. < 65 years) by 1.3% (p = 0.77) and -10.1% (p = 0.009) as compared with 0-7 parity group by -9.5% (p = 0.001) and -15% (p = 0.0001), respectively. CONCLUSION: Parity > 7 is associated with spinal trabecular bone loss in younger postmenopausal women as well as an osteoprotective effect against age-related bone loss, which counteracts the early negative effect. Therefore, parity should not be considered as a risk factor for postmenopausal osteoporosis.