If pregnant women stop smoking, babies are happier

WASHINGTON (Reuters) - Mothers who stop smoking while pregnant tend to have cheerier, more adaptable babies, British researchers reported on Wednesday.

Babies of women who continued to smoke while pregnant were notably grumpy, and the researchers believe that mothers who can muster the effort to kick the habit are also caring more for their babies in other ways.

Babies of non-smokers also are more temperamental than babies born to quitters, the researchers found -- which they said suggested that mothers who suspend smoking are doing something special.

Tobacco can affect the growth of a fetus and has been shown to also affect children if they breathe in their mothers' secondhand smoke.

But Dr. Kate Pickett at Britain's University of York thinks her team is on to something more. They have been following 18,000 British babies born between 2000 and 2002, as well as their mothers, who are taking part in a larger study.

They asked the mothers a number of questions about their babies' temperaments.

"There are things like whether or not a child is receptive to new things, whether they are frightened of strangers, whether their mood is cheerful or not," Pickett said in a telephone interview.

The mothers were classified as heavy or light smokers, never-smokers or quitters. The women who quit had noticeably more easygoing babies, Pickett and colleagues reported in the Journal of Epidemiology and Community Health.

"It's a significant association. We can be sure it's not due to chance," Pickett said.

"What we think: quitting smoking is a really difficult thing to do at any time. And we do know that most women who quit smoking when they are pregnant start smoking again afterwards," she said.

"So what they are doing is taking a very specific maternal action to protect their babies. We are seeing it as a marker for other characteristics of women who manage to quit. It may also be a marker for their easy temperament."

People who can quit smoking tobacco -- one of the most addictive substances known -- may pass on their genetic traits to their babies, the researchers said.

"Consistent with this, women who quit smoking in pregnancy have better general functioning, including more sustained relationships, more skillfulness in use of community resources and less disrupted and stressful life circumstances and are less likely to have a history of social problems and antisocial behavior compared to pregnancy smokers," they wrote.

The study showed that heavy smokers had the most difficult children, scoring low for positive mood.

"I think it is really important to avoid stigmatizing women who can't manage to quit," Pickett said. "And pregnancy is a stressful time."

Pickett's team is still following the babies and analyzing data from ages 3 and 5, when they can get input from teachers and caregivers.

(Editing by Julie Steenhuysen and John O'Callaghan)