Where There's Smoke, Reading Suffers

Smoking during pregnancy linked to lower reading skills in children

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Women have heard over and over not to smoke while pregnant. But the difference it can make is still sometimes surprising. A very positive surprise when considering children's reading skills.

A recent study has found that children scored much lower on reading skills if their mothers smoked during pregnancy.

Overall, the researchers found that children whose mothers smoked during pregnancy were much more likely to have lower reading skills or slower development in reading.

"Don't smoke while pregnant."

The study, led by Kelly Cho, PhD, of both Yale University School of Medicine and Harvard Medical School, aimed to determine whether children of mothers who smoked during pregnancy experienced any difficulties with reading skills.

A total of 5,119 children from the United Kingdom were assessed in terms of their reading speed, spelling, fluency accuracy, comprehension and ability to identify individual words. They were tested at age 7 and age 9.

The children were divided according to whether their mothers had no nicotine during pregnancy, more than 17 mg of nicotine per day during pregnancy or 17 mg or less nicotine daily. Seventeen milligrams was the amount selected because it is approximately equivalent to the total nicotine in a single package of cigarettes.

The researchers adjusted their analysis of the children's reading performance scores to account for the children's socioeconomic status, the relationship between the mothers and their children and 14 other possible factors that might also influence reading skills.

The children whose mothers smoked a high number of cigarettes (taking in over 17 mg a day) scored 21 percent lower on the reading assessments overall compared to the children whose mothers did not smoke. The children of smoking mothers had the most difficult time with was being able to identify single words, including having difficulties with phonics.

When the researchers considered the data in terms of a single classroom of 31 students, they estimated that a child whose mother smoked during pregnancy would be seven rankings lower in reading skills than a child whose mother didn't smoke while pregnant.

"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 senior author Jeffrey Gruen, MD, in a release about the study.

The study was published in the November issue of The Journal of Pediatrics. The research was funded by the United Kingdom Medical Research Council, the Wellcome Trust, the National Institutes of Health and the University of Bristol in the UK.

Reviewed by: 
Review Date: 
November 19, 2012
Last Updated:
April 1, 2013