Bone remodeling during pregnancy and post-partum assessed by metal lead levels and isotopic concentrations

- There are conflicting data on bone remodeling during pregnancy and post-partum
- We describe an alternative highly sensitive approach using levels of the metal lead and its isotopic composition
- Studies demonstrate bone resorption with increased lead release from the maternal skeleton in later pregnancy and lactation
- The data for the Australian subjects are consistent with multi-generational passage of lead.

Bone remodeling is normally evaluated using bone turnover markers/indices as indicators of bone resorption and formation. However, during pregnancy and post-partum, there have been inconsistent results between and within biomarkers for bone formation and resorption. These differences may relate to pregnancy-related changes in metabolism and/or hemodilution altering measured marker levels. An alternative approach to evaluating bone remodeling is to use the metal lead (Pb) concentrations and Pb isotopic compositions in blood. These measurements can also provide information on the amount of Pb that is mobilized from the maternal skeleton. Despite some similarities with accepted bone turnover markers, the Pb data demonstrate increased bone resorption throughout pregnancy that further continues post-partum independent of length of breast-feeding, dietary intake and resumption of menses. Furthermore the isotopic measurements are not affected by hemodilution. These data confirm calcium balance studies that indicate increased bone resorption throughout pregnancy and lactation. They also indicate potentially major public health implications of the transfer of maternal Pb burden to the fetus and new born.