Factors influencing the difference between maternal and cord blood lead

Aims: To determine the factors that affect why some infants receive higher exposures relative to the mother's body burden than do others. Methods: A total of 159 mother-infant pairs from a cohort of women receiving prenatal care at Magee-Womens Hospital in Pittsburgh, PA from 1992 to 1995 provided blood samples at delivery for lead determination. The difference between cord and maternal blood lead concentration (PbB) and a dichotomous variable indicator of higher cord than maternal PbB, were examined as indicators of relative transfer. Women were interviewed twice during the pregnancy about lifestyle, medical history, calcium nutrition, and physical activity. Results: Higher blood pressure was associated with relatively greater cord compared with maternal PbB, as was maternal alcohol use. Sickle cell trait and higher haemoglobin were associated with a lower cord relative to maternal blood lead PbB. No association was seen with smoking, physical exertion, or calcium consumption. Conclusion: While reduction in maternal exposure will reduce fetal exposure, it may also be possible to mitigate infant lead exposure by reducing transfer from the pregnant woman. Interventions aimed at reducing blood pressure and alcohol consumption during pregnancy may be useful in this regard.