Differential relationships between parent-child DXA and pQCT bone measures: Results from the Southampton Women's Survey.

AIM: To investigate the associations between indices of bone health in childhood and corresponding parental measures. METHODS: The Southampton Women's Survey characterised 12,583 non-pregnant women aged 20-34 years; 3158 subsequently had singleton live births. In a subset, dual-energy X-ray absorptiometry (DXA) measurements of bone area (BA), bone mineral content (BMC) and areal bone mineral density (aBMD) lumbar spine and total hip were obtained in the parent/offspring (aged 8-9 years) trios. Another subset of children (aged 6-7 years), and their parents, had peripheral quantitative computed tomography (pQCT; 4% and 38% tibia) measures. Using multivariable linear regression we examined relationships between mother/father and offspring, adjusting for parental age, habitual walking speed and education; offspring age and sex; and the corresponding bone measure in the other parent (ß-coefficients (95%CI) unit/unit for each bone measure). RESULTS: Data were available for 260 trios with DXA and 99 with pQCT. There were positive associations for BA, BMC and aBMD between either parent and offspring. Mother-child associations were of greater magnitude than father-child; for example, mother-child aBMD (ß = 0.26 g·cm-2/g·cm-2 (0.21,0.32)) and father-child aBMD (ß = 0.16 g·cm-2/g·cm-2 (0.11,0.21)), P-difference in ß = 0.007. In the subset with pQCT there was a positive association for mother-offspring 4% tibial total area (ß = 0.33 mm2/mm2 (0.17,0.48)), but little evidence of a father-offspring association (ß = -0.06 mm2/mm2 (-0.17,0.06)). In contrast offspring 38% cortical density was more strongly associated with this measure in fathers (ß = 0.48 mg·cm-3/mg·cm-3 (0.15,0.82)) than mothers (ß = 0.27 mg·cm-3/mg·cm-3 (-0.03,0.56)). In general mother-father differences were attenuated by adjustment for height. CONCLUSIONS: Whilst offspring bone measures are independently associated with those of either parent, the magnitude of the association is often greater for maternal than paternal relationships. These findings are consistent with an in utero influence on offspring growth but might also reflect genetic and/or epigenetic parent of origin effects. SUMMARY: In an established parent-offspring cohort, associations between parent and offspring bone indices were generally greater in magnitude for mother-offspring than father-offspring relationships.