Developmental psychologist Jan Frijters' latest research shows children whose mothers smoked while pregnant scored lower on reading tests.

Children whose mothers smoked more than a pack of cigarettes a day score lower on reading tests than those of mothers who did not smoke during their pregnancies.

This is the major finding of research done by Brock University and the Yale School of Medicine published online in the latest issue of The Journal of Pediatrics.

Brock researcher Jan Frijters explains that, other factors being equal, a child of a mother who smoked will be on average seven places lower in a class of 31 children in reading accuracy and comprehension.

“Reading is key to almost all areas of learning,” says Frijters. “Difficulty in reading is going to have long-term – and possibly deep – impacts on a child’s intellectual development, socialization, self-confidence and possibly future aspirations.”

Children in the study were tested at age seven and again at age nine.

“We do know that the results are not linked to a mother’s education, the economic status of the family, how much the mother and child spoke with each other, or even how many books they read together,” says Frijters, a developmental psychologist in the Department of Child and Youth Studies.

“We think nicotine may have a specific effect on a fetus’s developing brain,” he says. “That view is strengthened by the fact that the frequency and amount of smoking by the child’s father had no impact on the child’s reading.”

Frijters and his Yale colleagues analyzed data from more than 5,000 families involved in the UK-based Avon Longitudinal Studies of Parents and Children, which stretches back to 1990.

This is the first study to analyze the impact of smoking on specific aspects of children’s reading ability, including reading speed, accuracy and comprehension.