Even years after widespread lead abatement methods have been considered to be successful and childhood lead levels have dropped significantly, maternal exposure to lead may still be impacting birth outcomes according to research by Dr. Felicia Rabito, associate professor of epidemiology at the Tulane University School of Public Health and Tropical Medicine.
Dr. Rabito and her colleagues participated in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) birth cohort study. They measured blood levels in pregnant women during the second and third trimesters and at birth as well as cord blood lead levels.
The average blood lead level of study participants was representative of lead levels typically found in pregnant women in the United States. The study found that even at very low levels, lead levels did not fluctuate randomly throughout pregnancy, but followed patterns found in women with much higher lead levels with relatively increased levels found in the second trimester and rising throughout pregnancy. Although the increase in lead was measured at extremely low levels, researchers found that even these moderately increased levels were predictive of cord blood lead levels and were associated with lower birth weight and preterm birth.
Dr. Rabito’s research is consistent with a “life course” view of health. Although the women in the study have no current lead exposure, the researchers theorize that these women were exposed to lead when they were young and that the lead was stored in the mother’s bone.
Lead stored in the bone leeches into the bloodstream and becomes a source of exposure to the developing fetus. “Lead levels in the study were far below the currently recommended action level for pregnant women.
The take home message is that most people think that lead is no longer an issue and that’s just not the case,” says Dr. Rabito. Even at very low levels, the developing fetus may be impacted by the presence of lead leading to poorer birth outcomes and potential impacts on IQ and behavior during childhood. These findings, along with others documenting lead’s adverse effects at low levels, highlight the need for continued promotion of childhood lead prevention activities.
Dr. Rabito’s research was published in Reproductive Toxicology.