Cooper et al. [7] concluded that infant growth and physical activity in childhood are important determinants of peak bone mass in women. However, it has also been shown

that gains in bone mineral accretion during childhood via interventions such as increased physical activity and nutrient supplementation may only be transient, thus promoting the hypothesis that bone mass is ultimately governed by a homeostatic system which tends to return towards a yet-to-be defined set point [8]. Whether this set point is genetically predetermined needs to be further investigated. Our research group has shown that heritability of bone area (BA) and BMC by maternal descent is approximately 30 % in South African pre/early pubertal black selleck screening library and white children, despite ethnic differences in both body and bone size, as well

as in lifestyle [9]. The pattern of ethnic differences in bone strength in youth [10, 11] is similar this website to the reported ethnic differences in fracture rates in adults [12–14], suggesting that these differences in fracture rates may track back to differences in bone strength in childhood and adolescence. Although heritability has been shown to be an important determinant of bone mineral accrual and fracture risk in other countries [15], no information is available on the differences in bone mass and fracture patterns between families of different ethnic backgrounds in South Africa. In this study, we were interested in assessing the associations between bone mass and fracture history of mothers with those of their adolescent children. We hypothesized that as there is a strong association between the bone mass measurements of adolescent–biological mother

pairs, maternal bone mass will influence fracture prevalence in their adolescent offspring and that a history of fractures in the mother or other siblings check will be associated with an increased risk of fractures in the adolescent. Methods Study population Data from 1,389 adolescent–biological mother pairs from the Birth to Twenty (Bt20) longitudinal study of child health and development were used. All eligible neonates (n = 3,273) born within a 7-week period (April 23 to June 8, 1990) in the greater Johannesburg metropolitan area in South Africa were recruited at birth into the Bt20 study. Although the total cohort is demographically similar to long-term resident families living in Soweto, Johannesburg, the cohort under represents white children due to white families generally utilizing private practitioners and facilities which were excluded during initial enrolment. To compensate for this, at the age of 10 years, we recruited a supplementary sample of 120 white children born during the same period as the cohort children in 1990 into the bone health sub-study of the Bt20 cohort.