Women who smoked during pregnancy were more likely to report having children with behavioral problems, and researchers think the reason could be fetal brain damage, the BBC reported Nov. 3.

Researchers from the U.S. and U.K. studied more than 14,000 mother-and-child pairs, scoring the women as light or heavy smokers and interviewing them about the behavior of their three-year-old children. The authors found that heavy smokers were 80 percent more likely to have boys with conduct problem than nonsmokers, while light smokers faced a 44-percent increased chance of having male children with behavioral problems.

Smokers also were more likely to have children who were hyperactive or had attention-deficit disorders.

"Smoking in pregnancy may have direct effects on the fetal development of brain structure and functioning which has been shown in studies of rats," said lead researcher Kate Pickett of the University of York. "Or it may be a marker for the transmission of processes between the generations that are associated with both smoking in pregnancy and behavior problems in children."

The study was published in the November 2009 issue of the Journal of Epidemiology and Community Health.