Mom's caffeine harms pups' brain cells.

Rats born to mothers who drank caffeinated beverages throughout their pregnancies had abnormal brain-cell function, researchers report.

Experts already recommend that pregnant women limit their caffeine to 300 milligrams per day--about the amount in three cups of coffee. Although this moderate consumption is considered safe, Deborah Soellner and Joseph Nunez of Michigan State University in East Lansing wondered whether it could still have significant effects on youngsters' brains.

The researchers provided some pregnant rats with free access to caffeinated water. On average, the animals consumed 3 to 4 mg of caffeine daily, the equivalent of the recommended limit for pregnant women. Other pregnant rats received only plain water.

When the pups were born, the researchers took samples of cells from each baby's hypothalamus. Soellner and Nunez tested the cells' responses to various chemicals that brain cells use to communicate, such as the neurotransmitters gamma-aminobutyric acid and glutamate.

The scientists found that cells from the caffeine-exposed and caffeinefree pups behaved differently. The response in the caffeine-exposed pups was heightened for certain neurotransmitters but dampened for others. Since some of these signaling chemicals affect brain development, the researchers suggest that caffeine during pregnancy may affect children's later brain function.

"Maybe human studies on caffeine consumption during pregnancy should be reevaluated," Nunez says.--C. B.