Exposure to these solvents could increase the risk of having a baby with a heart defect by 60 percent to 70 percent, Gilboa said. The absolute risk, however, is low.
"The overall risk of having baby with a heart defect is one in 1,000 or less, so exposure might mean going from one case to two cases," she said.
Organic solvents are used for dissolving or dispersing things like fats, oils and waxes, and in chemical manufacturing. They are found in paints, varnishes, adhesives, degreasing/cleaning agents, dyes, polymers, plastic, synthetic textiles, printing inks and agricultural products, according to the report.
Most of these solvents are highly volatile and can be breathed in or absorbed through the skin or mouth.
Gilboa's team collected data on 5,000 women exposed to these solvents in their workplace early in pregnancy. They looked for associations between 15 types of congenital heart defects and exposure to these chemicals.
The researchers found that 4 percent of women whose babies did not have birth defects -- and 5 percent of those who did -- were exposed to organic solvents at the time they were trying to conceive or early in pregnancy.
When they accounted for these findings using other published material, they increased to 8 percent and 10 percent, respectively.
"These findings are encouraging," Katz said. The weakness of both of these studies, however, is that the work experience is self-reported, so it is subject to faulty memory of what the actual exposure was at the critical time, he said.
Another caveat about the two studies: while they uncovered an association between parents' occupations and birth defects, they did not prove a cause-and-effect relationship.
For more on birth defects, visit the March of Dimes.
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