Clark Emma M, Ness Andy, Tobias Jon H
Community Based Medicine, University of Bristol, United Kingdom.
J Bone Miner Res. 2005 Dec;20(12):2082-9. doi: 10.1359/JBMR.050808. Epub 2005 Aug 8.
We studied relationships between social position of the mother in pregnancy and bone mass of the child at age 9.9 years. The tendency for social position to increase bone area and bone mass through a positive influence on height was opposed by a negative effect of social position on weight and fat mass.
Evidence that social factors influence skeletal growth raises the possibility that bone mass acquisition in childhood is socially determined.
To clarify the role of social factors in bone mass acquisition in childhood, we studied relationships between these variables in the Avon Longitudinal Study of Parents and Children (ALSPAC). Measures of the mother's social position during pregnancy were linked to DXA results obtained at age 9.9 years in 6,702 children. Linear regression analyses were carried out after adjusting for age and gender. Because social position may affect height and weight of the child, analyses were repeated after adjusting for these additional variables.
Measures of social position in pregnancy were unrelated to total body BMC in analyses adjusted for age and gender alone. However, after adjusting for height, which was positively related to social position, a strong negative association was observed between BMC and housing tenure (p < 0.001), maternal education (p < 0.001), paternal education (p < 0.001), and social class (p < 0.001). Similar results were obtained for bone area. After adjusting for weight as well as height, an association between social position and BMC and bone area was no longer observed. Hence, social position seems to exert opposing height- and weight-dependent effects on BMC and bone area in childhood. In further analyses, we found that adjusting for fat mass of the child led to similar results to those obtained with weight.
Social position in childhood seems to be positively related to bone mass acquisition in childhood as a consequence of enhanced gain in height (i.e., longitudinal growth). However, this influence is counteracted by the tendency for increased fat deposition in those from a lower social position to increase bone area, presumably reflecting the stimulation of appositional bone growth.
我们研究了孕期母亲的社会地位与9.9岁儿童骨量之间的关系。社会地位通过对身高的积极影响来增加骨面积和骨量的趋势，被社会地位对体重和脂肪量的负面影响所抵消。
社会因素影响骨骼生长的证据表明，儿童期骨量的获得可能受社会因素决定。
为阐明社会因素在儿童期骨量获得中的作用，我们在阿冯父母与儿童纵向研究（ALSPAC）中研究了这些变量之间的关系。孕期母亲社会地位的测量指标与6702名儿童9.9岁时获得的双能X线吸收法（DXA）结果相关联。在调整年龄和性别后进行线性回归分析。由于社会地位可能影响儿童的身高和体重，在调整这些额外变量后重复进行分析。
仅在调整年龄和性别的分析中，孕期社会地位的测量指标与全身骨矿含量（BMC）无关。然而，在调整与社会地位呈正相关的身高后，观察到BMC与住房保有情况（p < 0.001）、母亲教育程度（p < 0.001）、父亲教育程度（p < 0.001）和社会阶层（p < 0.001）之间存在强烈的负相关。骨面积也得到了类似结果。在调整体重以及身高后，未再观察到社会地位与BMC和骨面积之间的关联。因此，社会地位似乎在儿童期对BMC和骨面积产生相反的、依赖于身高和体重的影响。在进一步分析中，我们发现调整儿童的脂肪量会得到与调整体重时相似的结果。
儿童期的社会地位似乎因身高增长增加（即纵向生长）而与儿童期骨量获得呈正相关。然而，这种影响被社会地位较低者脂肪沉积增加从而增加骨面积的趋势所抵消，这可能反映了对骨表面生长的刺激。
