Low lead levels linked to higher blood pressure during labor.
Wells, EM, A Navas-Acien, JB Herbstman, BJ Apelberg, EK Silbergeld, KL Caldwell, RL Jones, RU Halden, FR Witter and LR Goldman. 2011. Low level lead exposure and elevations in blood pressure during pregnancy. Environmental Health Perspectives http://dx.doi.org/doi:10.1289/ehp.1002666.
Even at very low levels, lead in cord blood is associated with higher blood pressure readings in pregnant women giving birth, report researchers in the journal Environmental Health Perspectives.
The study of the pregnant women in Baltimore, Md., broadens the understanding of lead levels associated with high blood pressure in women giving birth. It shows that even low levels thought to be below concern are associated with blood pressure increases. It also found that those women who had higher overall blood lead levels at the time of delivery also had higher blood pressure readings during the birth process.
High blood pressure while pregnant may lead to pre-eclampsia – a common but dangerous birth complication – and an increased risk of future heart disease. No association was found in this study between lead exposure and pre-eclampsia.
Exposure to lead levels higher than those normally seen in the United States has been associated with higher blood pressure in adults and pregnant women. The blood lead levels in this study were lower than the average values observed previously in the U.S. population.
However, more and more studies are finding that even very low levels of lead can affect health. Some experts believe there is no safe level of lead exposure.
Blood lead levels in general have declined dramatically after lead-containing paints and gasoline were banned in the United States in the 1970s. The Centers for Disease Control and Prevention set 5 micrograms per deciliter of blood as the limit of concern in pregnant women and advises pregnant women with blood lead levels above this to seek help in reducing their lead exposure. Data from this study suggest that even this limit may not be enough to protect women’s health.
Researchers measured lead levels in umbilical cord blood after the delivery of almost 300 babies at the Johns Hopkins Hospital in Baltimore. Medical records provided information on the blood pressure of mothers at the time of admission to the hospital and the maximum blood pressure observed during labor and delivery.
The researchers divided the women into four groups based on their lead exposure levels. Women with the highest lead exposure had higher maximum blood pressure and higher admission blood pressure levels than women with the lowest lead exposure.
They found that an increase of about 20 parts per billion (2 micrograms of lead per deciliter of blood) led to a 10 percent increase in blood pressure during labor and delivery. The researchers considered and took into account other factors that might affect blood pressure, such as smoking and being overweight.
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