Cole, Zoë A.
How do early environment, diet and physical activity interact to determine bone development in young children?
University of Southampton, School of Medicine,
Aims: To examine the interaction of maternal factors (body composition, physical activity, diet and cigarette consumption) with childhood factors (body composition, diet & physical activity) in the determination of bone mineral accrual by aged 6 years, assessed by a) bone densitometry b) hip structural analysis c) pQCT measurement of the tibia in children born to mothers from the Southampton Women?s Survey.
Methods: Children were recruited at 6 years old from the Southampton Women's Survey. Their mothers? diet, lifestyle and anthropometry had previously been characterised before and during pregnancy. The children underwent measurement of bone mass by DXA, including hip structure analysis (HSA), and by pQCT at the tibia. Physical activity was assessed by accelerometry (Actiheart) for 7 continuous days. Diet was assessed using a validated food frequency questionnaire and detailed anthropometric data was also collected.
Results: There were 530 children who attended for a DXA scan. Of these, 148 also underwent pQCT assessment. Increased childhood height, weight and milk intake were associated with increased measures of bone size; increased physical activity levels and greater lean mass were positively associated with increased volumetric BMD. Fat mass was negatively associated with volumetric BMD. Whilst maternal height, weight, exercise in late pregnancy and pre pregnancy calcium intake were associated with increased bone size in the offspring, this association was removed after adjusting for childhood factors suggesting that maternal body composition and lifestyle may predict the child?s body composition and lifestyle.
On assessment of growth patterns in this cohort, children were who born small tended to remain small at aged 6 years. Increased catch up growth was associated with increased maternal height and total milk intake at aged 3 years. Rapid weight gain during childhood was associated with maternal smoking during pregnancy.
Conclusions: We have demonstrated that maternal and childhood factors influence bone mineral accrual and bone strength, in the developing child. Whilst many important maternal determinants measured (such as physical activity levels) were shown to influence the corresponding determinants in the offspring, other factors such as maternal cigarette smoking were shown to have persistent independent effects on post-natal growth and body composition.
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