Inter-generational lead: Lead transfer to the foetus

- By Robert Taylor, Researcher for The LEAD Group

One of the major problems with lead is its capacity to be transferred to the foetus. There is a strong correlation between a mother’s blood lead level and that of her newborn, with blood lead levels of newborns equal to or slightly lower than that of  their mother’s. (Goyer 1990) while at some points in the pregnancy it may even exceed maternal blood lead levels (Lagerkwist 1996). In rare circumstances foetal lead levels can be two to three times higher than the mother’s (Horowitz 2001,Tait 2002). 

There is evidence that high blood pressure increases the transfer of lead to the foetus (Harville 2005) as does alcohol consumption (Rhiands1997, Ernhardt et al 2004, Harville 2005).

 Much of the total foetal lead is sourced from the mother’s bones. Indeed maternal bone lead may be a better measure of foetal lead exposure than the traditional birth cord measurements with trabecular bone being most predictive of reduction in MDI (mental development index) scores (Gomma 2002). The gradual depletion of bone lead, baring subsequent heavy exposure, in each pregnancy means higher lead exposure for babies born early in the family birth order (Rabinowitz & Needleman 1984, Korrik 2002, Tellez-Rojo et al 2002, Al- Jawadi et al 2011) though it is possible that the proportion of lead transferred to the child may increase with latter pregnancy (Rothenburg 1989).

Unfortunately chelation during pregnancy does not reduce the contamination levels of the foetus and indeed may increase them (Tait 2002). It is thought that chelation may lead to increased mobilisation of lead from body stores such as bone, so its short term impact could increase foetal lead exposure while having little long term effect on developmental outcomes (Dietrich et al 2004).

(Miranda 2010)

(Tait 2002)