Maternal diet during pregnancy is associated with bone mineral density in children: a longitudinal study

Objective: To describe the association between maternal diet during the third trimester of pregnancy and bone mass in 8 y-old male and female children. Design: Longitudinal study. Setting: Southern Tasmania between 1988 and 1996. Subjects: One-hundred and seventy-three 8-y-old male and female children with adequate maternal dietary information taking part in a study of bone mineralization. Results: After adjustment for confounders, femoral neck bone mineral density (BMD) was positively associated with magnesium and phosphorus density of the maternal diet; lumbar spine BMD was positively associated with magnesium, phosphorus and potassium and negatively associated with fat density while total body BMD was positively associated with magnesium, potassium and protein and negatively associated with fat density (al P<0.05). After further adjustment for other significant dietary factors, the only significant remaining associations observed were for phosphorus and fat at the lumbar spine, although the adjusted goodness of fit of the models improved compared to those including one dietary variable. A child in the 'optimal' levels of dietary exposures had significantly higher adjusted BMD at all sites (femoral neck, +5.5%, lumbar spine, +12%, total body, +6.8%). Calcium intake was not associated with BMD at any site? possibly due to a high average intake. Conclusions: This study reports a substantial association between in utero diet in a well-nourished population and later bone mass in their children. However, it does not allow identification of the dietary components of greatest importance, indicating that these results should be regarded as hypothesis-generating. Further longitudinal studies in other populations are required to confirm that dietary manipulation during pregnancy has a role to play in the early life prevention of osteoporosis.