There’s plenty of data showing how harmful smoking can be, and that goes for both smokers and the people around them. Two studies published in Pediatrics point out how indirect the effects can be. A study of paternal smoking in Hong Kong finds that children whose fathers smoke are heavier at seven and 11 years old than their counterparts who have non smoking dads; and investigation of children in Britain and Brazil finds that moms who smoke may be trigger behavioral problems in their children.
In the Hong Kong study, researchers at the University of Hong Kong studied a unique cohort of 6519 children born in 1997, for whom health records and information on household smoking was available. Among the cohort, more fathers than mothers lit up, and children of smoking fathers showed a greater change from average BMI charts than those whose fathers did not. Because fathers in the Chinese culture have a minimal role in diet and lifestyle choices of their children, the authors speculate that the fathers’ cigarette habit was affect their children’s obesity via biological mechanisms, through second hand exposure.
The second study, led by Marie-Jo Brion at the University of Bristol, aimed to adjust for all of the usual factors that might influence children’s mental and social health states—these included factors such as depression in the parents, parental education, the family’s social status and income, and parental alcohol consumption. By comparing two populations—a middle class group in Britain and a lower income group in Brazil, where smoking rates are generally higher—the researchers also hoped to isolate smoking effects that are independent of socioeconomic status. If the effect of lighting up persisted in both groups, they surmised, then it would suggest a stronger potential causal relationship.
In the end, mother’s smoking increased by an average of 53% the risk that children in both populations would be aggressive, break rules, bully, cheat or otherwise display disobedient behavior, compared to kids of non smoking moms. The effect of paternal smoking was nearly half that of maternal smoking, which leads the researchers to conclude that smoking’s effect on behavior is occurring during pregnancy. Among both groups, an average of 18% of mothers continued to smoke more than 20 cigarettes per day during pregnancy, despite public health messages warning about the potentially harmful effects of the habit on the growing fetus.
And that’s where Brion hopes studies like hers can have an impact. “We’re keen on studying the effects of smoking in children among women who are still smoking during pregnancy, to get a clearer picture of the effects on child development that might help to lower that a bit,” she says.