THURSDAY, March 13 (HealthDay News) -- Women who quit smoking during pregnancy may be more likely to have an easygoing child, according to British researchers.

The researchers analyzed data on more than 18,000 children born in the United Kingdom between 2000 and 2002. The mothers' smoking habits during pregnancy were noted, and they were classified as either nonsmokers, light smokers, or heavy smokers (more than 10 cigarettes a day). At age 9 months, the children's temperaments were assessed for things such as positive mood, receptivity to new things, and regular sleep and eating patterns.

The researchers found that children born to pregnant women who stopped smoking were more easygoing -- least likely to display unpredictable behavior or to become distressed when faced with new situations or things -- than children born to nonsmokers or heavy smokers.

The study also found that children born to heavy smokers were most likely to have the lowest scores for positive mood.

The findings were published in the Journal of Epidemiology and Community Health.

The study authors noted that previous research in animals showed that nicotine is a behavioral toxin and that having a difficult temperament can be a forerunner of antisocial behavior.

Pregnant women who smoke not only expose their unborn babies to harmful chemicals that could affect their development, but these mothers also may pass on traits and behaviors associated with their smoking during pregnancy, the researchers said.

They noted that quitting smoking during pregnancy is associated with an urge to protect the baby rather than any intention to kick the habit in the long term, and smoking relapse rates are high after these women give birth.

However, quitting smoking during pregnancy shows that a woman has the capacity to adapt to different circumstances and the ability to plan and delay gratification -- traits that seem to be absent in women who continue smoking during pregnancy, the study authors said.

More information

The American Lung Association has more about smoking and pregnancy.

-- Robert Preidt

SOURCE: British Medical Journal, news release, March 13, 2008

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