Lead Exposure During Pregnancy Affects Blood Pressure
During pregnancy, blood pressure is typically slightly above normal because the heart pumps harder as blood volume increases. Prolonged high blood pressure, however, can be a life-threatening condition if it leads to preeclampsia or eclampsia. Scientists from George Washington University have found that exposure to lead, even at low levels, can increase the risk of pregnancy hypertension.
Blood Lead Levels Below Maximum Allowed Increase Risk of Hypertension
High blood pressure problems occur in 6 to 8 percent of all pregnancies in the United States. In about 70% of cases, according to the National Institutes of Health, these are first-time pregnancies. The agency also notes that while the overall proportion of pregnancies with gestational hypertension has remained stable over the past decade, the rate of preeclampsia has increased by nearly one-third.
Lynn Goldman MD MS MPH, Dean of GWU’s School of Public Health and Health Services, and a team from Johns Hopkins Hospital monitored 285 pregnant women. About 25% had a lead level higher than about 1 microgram/dL of umbilical blood. While this level is below the threshold set by the Centers for Disease Control and Prevention, those women had an average of 6.9 mm/Hg increase in systolic pressure and 4.4 mm/Hg increase in diastolic pressure.
The researchers did not find an associated correlation between blood lead levels and preeclampsia incidence. But Dr. Goldman does believe the study suggests that there are cardiovascular effects of lead in pregnant women at lower levels than previously suggested.
The CDC advises action to be taken to reduce exposure to lead when pregnant women or children have a blood level higher than 5 micrograms per deciliter.
The best way to reduce lead in a woman’s blood is to prevent exposure, not only during pregnancy but also prior to pregnancy, says first author Ellen Wells PhD, a postdoctoral scholar at Case Western Reserve University.
The workplace is a good place to start, suggests Dr. Goldman. According to the Washington State Department of Labor and Industries, ninety-four percent of adults with elevated blood lead levels are exposed to the compound in the workplace. Workers than can bring the contaminant home and expose their families. The study also finds that approximately two to three percent of children with blood levels exceeding 10 mcg/dL were exposed by lead from the parents’ workplace.
“Because lead is stored in bones for many years,” says Dr. Wells, “even childhood exposure could impact lead levels in pregnancy.”
Lead exposure has steadily decline in the United States since the nineties, primarily because of bans on lead in gasoline, paint, and drinking water, but more restrictions on the metal should remain a public health priority. In December, President Obama was asked to sign into law a bill that would reduce exposure to lead by tightening restrictions on lead in drinking water plumbing.
The American Academy of Pediatrics also supports a restriction on lead in the environment and the CDC has named a reduction in lead exposure as one of its national health objectives for 2010.