Children whose mothers used cell phones frequently during pregnancy are more likely to have behavior problems, especially if they themselves are cell phone users.

A team of scientists looked at a group of more than 13,000 children. When the children reached age 7, mothers were asked to complete a questionnaire about their own cell phone use in pregnancy and their child’s use of cell phones, as well as their children’s behavior and health.

Children with both prenatal and postnatal cell phone exposure were 80 percent more likely to have emotional problems, conduct problems, hyperactivity, or problems with peers. Children who were only exposed prenatally also had a higher likelihood of behavior problems, but not as high as those who were also cell phone users.