FRIDAY, July 21, 2006 (HealthDay News) -- On top of its other risks to baby, maternal smoking during pregnancy may help trigger hearing-related cognitive defects in newborns -- and fetal exposure to nicotine may be to blame, researchers say.
That finding raises the concern that women who use the nicotine patch in an attempt to quit smoking during pregnancy might still be putting their babies at risk.
Scientists had already recognized the link between smoking during pregnancy and infant hearing trouble. This study, by researchers at the University of California, Irvine (UCI), is the first to identify nicotine as the likely culprit.
In research with rats, the UCI team showed that nicotine exposure during the rats' equivalent of a human's third trimester of pregnancy resulted in hearing-related cognitive problems in rat pups. Further research showed that these deficits were likely caused by damage to receptors in the brain that are sensitive to nicotine.
"This study is significant because it suggests to us precisely what aspect of smoking is so harmful in pregnancy when it comes to cognitive hearing deficits," researcher Raju Metherate, associate professor of neurobiology and behavior at the university, said in a prepared statement.
"Most women who smoke find it difficult to quit during pregnancy. For them, doctors often prescribe a nicotine patch. While that does protect the fetus from the well-known physical underdevelopment related to harmful chemicals in cigarette smoke, exposure to nicotine appears to be enough to cause serious problems on its own, in terms of brain development," Metherate said.
Children with cognitive hearing deficits can experience a number of problems, including difficulty understanding speech in noisy settings, an inability to understand information that's presented verbally, and being unable to tell the difference between similar sounds.
The findings are published in this week's online issue of the European Journal of Neuroscience.
More information
The American Medical Association has more about smoking and pregnancy.
