TUESDAY, Feb. 14 (HealthDay News) -- High blood levels of cadmium in women and high levels of lead in males can make it difficult for couples to conceive, new research suggests.

Cadmium is a metal that is used in batteries, metal coatings and plastics, but the most common source of cadmium exposure is cigarette smoke. Common sources of exposure to lead in the United States include lead-based paints in older homes, lead-glazed pottery, and contaminated soil and water.

Exposure to these toxic metals is known to have a number of effects on human health, but their impact on human fertility has not been extensively examined, according to researchers at the U.S. National Institutes of Health and colleagues.

The new study included 501 couples in Michigan and Texas who were trying to conceive. The couples were followed for up to one year, or until pregnancy was confirmed. The women were aged 18 to 44 and the men were all older than 18.

Using statistical measurements of the participants' blood concentration of the metals, the investigators found that, in the women, the probability of pregnancy was reduced by 22 percent with each increase in the blood cadmium concentration. In men, the probability of conceiving was reduced by 15 percent for each increase in their blood lead concentration.

The study was released online Feb. 4 in advance of publication in an upcoming print issue of the journal Chemosphere.

"Our results indicate that men and women planning to have children should minimize their exposure to lead and cadmium," principal investigator Dr. Germaine Buck Louis, director of the division of epidemiology, statistics and prevention research at the U.S. National Institute of Child Health and Human Development, said in an NIH news release.

"They can reduce cadmium exposure by avoiding cigarettes or by quitting if they are current smokers, especially if they intend to become pregnant in the future. Similarly, they can take steps to reduce their exposure to lead-based paints, which may occur in older housing, including during periods of home renovation," Louis advised.

He added that the "findings highlight the importance of assessing couples' exposure jointly, in a single, combined measure. Males matter, because couples' chances of becoming pregnant each cycle were reduced with increasing blood lead concentrations in men."

While the study uncovered an association between higher concentrations of these metals in blood and decreased fertility, it did not prove a cause-and-effect relationship.

More information

The U.S. Centers for Disease Control and Prevention has more about lead and how it affects health.