However, the new recommendations from the American College of Obstetricians and Gynecologists (ACOG) say doctors should ask women a series of questions to see if they might be at risk for high lead exposure.

If that's the case, a blood test for the heavy metal should be carried out, according to ACOG, so that precautionary steps can be taken if necessary.

Lead is toxic and particularly harmful for developing nervous systems. The metal can be passed through a pregnant woman's placenta to the fetus, or through breast milk to a baby.

Still, only about one percent of American women of child-bearing age have higher-than-normal lead levels in their blood (5 micrograms per deciliter or more).

"The majority of women in the U.S. have very low lead exposures," said Dr. Eva K. Pressman, who worked on the new recommendations. "The current recommendation is not to do blood screening on every pregnant woman, but to do some sort of exposure history."

The group lists a dozen risk factors that should trigger a blood test, including having remodeled older homes that have lead paint and using imported cosmetics or alternative medicines that may be contaminated.

If the blood levels are elevated, a number of steps can be taken - from eliminating the environmental culprit to taking supplements like iron and calcium that curb lead absorption, or medical treatments.

Lead poisoning can cause hypertension, headache, fatigue and behavioral changes. And very high levels of the metal may lead to seizures, coma or even death. In infants, one of the biggest concerns is the metal's effect on IQ.

But Pressman stressed that high lead levels don't necessarily mean a pregnant woman's baby will have problems.

"Every pregnancy is affected slightly differently, so there are pregnancies with high exposures that are not affected and pregnancies with low exposures that are being affected," Pressman told Reuters Health.

Currently, states have different rules about screening or otherwise assessing pregnant or breastfeeding women for lead exposure. But Pressman said routine screening is not very common.

She acknowledged that asking women about their exposure to lead might have some unfortunate consequences, including leading some to consider abortion if they end up screening positive for high levels.

"I think the biggest harm is worry, and perhaps unnecessary worry because we don't know that those levels will cause harm in a given pregnancy," Pressman said.

ACOG's recommendations draw on a much larger document from the Centers for Disease Control and Prevention and are meant to give doctors a set of handy instructions they can use in their daily practice.

SOURCE: bit.ly/O0H5Rt American College of Obstetricians and Gynecologists Committee Opinion #533, online July 23, 2012.

• A Permanent Economic Emergency