Smoking During Pregnancy Lowers Reading Scores in Kids

First Posted: Nov 20, 2012 04:24 AM EST

Health hazards tied to smoking can spill down generations. Children born to mothers who smoke more than one pack a day during pregnancy not only suffer health problems but struggle with reading comprehension too.

This study was conducted by Dr. Jeffrey Gruen, professor of pediatrics and genetics at Yale School of Medicine, and colleagues.

The researchers analyzed data of more than 5,000 children that were involved in the Avon Longitudinal Study of Parents and Children (ALSPAC), a large-scale study of 15,211 children from 1990-1992 at the University of Bristol in the United Kingdom.

The researchers compared the performance of the children based on seven specific tasks. The tasks included reading, speed, single word identification, spelling, accuracy, real and non-word reading and reading comprehension with maternal cigarette smoking, after adjusting the socioeconomic status, mother-child interactions and 14 other potential factors.

The researchers noticed that, on an average the children with high levels of nicotine (the minimum being one pack of cigarettes per day) in utero scored 21 percent lower in these areas than classmates born to non-smoking mothers. The children were tested at age seven and again at age nine.

It was noticed that among students who came from similar backgrounds and education, a child of a smoking mother will, on average, be ranked seven places lower in a class of 31 in reading accuracy and comprehension ability.

"It's not a little difference -- it's a big difference in accuracy and comprehension at a critical time when children are being assessed, and are getting a sense of what it means to be successful," said Gruen, who also points out that the effects of smoking in pregnancy are especially pronounced in children with an underlying phonological (i.e., speech) deficit, suggesting an interaction between an environmental exposure (smoking) and a highly heritable trait (phonological ability).

"The interaction between nicotine exposure and phonology suggests a significant gene-by-environment interaction, making children with an underlying phonological deficit particularly vulnerable," he said.

The findings are published in the current issue of The Journal of Pediatrics.

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