Health experts have known for decades that high levels of lead in the bloodstream can be bad for your health.  But a new study has found that even low lead levels can have a harmful affect - particularly for pregnant women and their babies.

The study, conducted at Johns Hopkins Hospital in Baltimore, Maryland, looked at the links between the level of lead in a pregnant woman's blood and her blood pressure at the time she was admitted to the hospital to deliver her baby.  Researchers found that even low lead levels - levels that are currently thought to be safe - are associated with blood pressure increases both at the time the woman is admitted to the hospital and throughout her labor and delivery.  

For the study, researchers measured umbilical cord lead levels after the delivery of almost 300 babies. They then used medical record data on the blood pressure of mothers at the time of admission to the hospital as well as her blood pressure readings throughout labor and delivery to determine if there were a link between lead levels and blood pressure.

The researchers divided the women into four groups based on their lead exposure levels. They found that women with the highest lead levels also had higher maximum blood pressure and higher admission blood pressure levels than women with the lowest lead exposure.  Specifically, an increase in lead levels of about 20 parts per billion - which works out to 2 micrograms of lead per deciliter of blood - led to a 10 percent increase in blood pressure during labor and delivery. This research also took into account other factors that might affect blood pressure, such as family history, smoking, and weight.

According to the Centers for Disease Control and Prevention, 5 micrograms of lead per deciliter of blood is the 'limit of concern' in pregnant women.  The goup advises pregnant women with blood lead levels above this to get medical attention and help in reducing their lead exposure. However, this study suggests that even this limit may not be enough to protect a pregnant women’s health - or her baby's.

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