Children who were exposed to cocaine in the womb show poorer-than-average language skills during their early years and do not catch up, new research suggests.

In a study that followed nearly 400 children from birth to age 6, researchers found that those whose mothers used cocaine during pregnancy showed persistently poorer language ability. This was true even when the researchers accounted for factors like the mothers’ vocabulary and family income.

Dr. Barbara A. Lewis and colleagues at Case Western Reserve University in Cleveland, Ohio, report the findings in the journal Pediatrics.

Research has tied prenatal cocaine exposure to a number of developmental delays and behavioral problems in childhood. For their study, Lewis and her colleagues tracked the effects of cocaine exposure on children’s language development over time.

The study included 209 children whose mothers had used cocaine during pregnancy and 189 children whose mothers had not abused the drug. At ages 1, 2, 4 and 6, the children took standard tests of their ability to understand and effectively use language.

Their mothers also took tests of vocabulary and general intelligence, and were interviewed about their caregiving skills. If a child had been placed in a foster home or adopted, the current caregiver was tested and interviewed.

Overall, Lewis’s team found, cocaine-exposed children performed more poorly on the language tests from early on, and did not catch up over time. Home environment and other factors did not change this link.

In addition to these drug effects, the researchers also found that children whose mothers smoked cigarettes during pregnancy performed more poorly on the language tests. The effect was over and above that of any cocaine use.

“The present findings indicate that tobacco exposure is additive to the risk of (cocaine-exposed) children for language deficits,” Lewis and her colleagues write.

Pediatricians, they conclude, need to be aware of the language delays linked to prenatal cocaine and tobacco exposure, and step up their efforts to detect such problems.

SOURCE: Pediatrics, July 2007.