Parents who quit smoking may be less likely to relapse when they discuss the dangers of cigarettes with their children, a U.S. study suggests.

Researchers followed almost 700 ex-smokers with children for one year. Half of the parents received a series of mailers with educational materials explaining the risks of tobacco and activities to help them discuss these dangers with their children. The other parents served as a control group and didn't get any help.

After one year, the parents supported by mail were twice as likely to still be abstinent.

More research is needed to explain why this happened because the findings came from a project designed to test something different - whether parents prompted to talk about cigarettes with their kids might help prevent their children from smoking, noted lead study author Christine Jackson.

It's possible, however, that talking to kids helped parents cement their own identities as non-smokers, or that the conversations created a feeling of cognitive dissonance that made it difficult for participants to advocate against smoking while being smokers themselves, said Jackson, a senior research scientist at RTI International in Research Triangle Park, North Carolina.

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"Our research is important because it suggests an entirely new approach to helping adults, specifically adults who are parents of school-aged children, succeed in quitting smoking," Jackson said by email.

To understand how parent-child conversations about smoking might influence tobacco use, researchers asked parents of children aged 8 to 10 years old to participate in a study when they called a smoking cessation hotline available in 11 U.S. states.

Parents were around 37 years old at the start of the study, and they had typically started smoking when they were about 16.

Most of them had tried to quit at least once before the current attempt and had a previous daily habit of at least 20 cigarettes, or about a pack a day. Many parents also lived in households with at least one or two current smokers.

The parents in the support group received six magazines with tips to prepare them for conversations about smoking with their children, as well as supplies to complete structured anti-smoking activities with their children.

Only 465 out of the original 689 parents remained in the study by the end of the year. When researchers counted all of the dropouts as parents who relapsed, the effect of the mailers remained meaningful, though smaller.

After accounting for the dropouts, parents who received mailers were still 58 percent more likely to remain abstinent by the end of the study, the authors report in Nicotine and Tobacco Research.

In addition to the high dropout rate, other shortcomings of the study include the reliance on parents to accurately report whether they remained abstinent and the lack of data to explain why parents who received mailers were more likely to avoid tobacco.

Even so, the findings suggest that parents may reinforce what they know about the benefits of smoking cessation by teaching these lessons to their children, said Jonathan Bricker, a behavioral scientist at the University of Washington and Fred Hutchinson Cancer Center in Seattle.

"Humans tend to want to act consistent with what they teach others," Bricker, who wasn't involved in the study, said by email. "By teaching your child, you hold yourself more accountable. If you teach it, you are more likely to do it yourself."

Regarding the experiment's original focus, Bricker noted, previous research has found parents who stop smoking when their children are young may cut the risk that their kids will start smoking by as much as 40 percent.

When parents quit, this can also nearly double the odds that any children who smoke may also quit, he added.