Children exposed to secondhand smoke at home are more likely to have an increased waist circumference and higher body mass index (BMI) by age 10 years, according to a report published online ahead of print June 11 in Nicotine and Tobacco Research. 

Lead author Linda S. Pagani, PhD, and colleagues analyzed data on the behavior of 2,055 families and outcomes for their children. They found that by age 10 years, children who had been intermittently or continuously exposed to smoke were likely to have waists that were up to three-fifths of an inch wider than their peers who were not. Their BMIs were likely to be 0.48 to 0.81 points higher. Their findings suggest the effect of secondhand smoke exposure before age 10 years is almost as great as the effect of smoking while pregnant, according to the authors. 

“Early childhood exposure to secondhand smoke could be influencing endocrine imbalances and altering neurodevelopmental functioning at this critical period in hypothalamic development, thus damaging vital systems, which undergo important postnatal growth and development until middle childhood, ie, the period that we’ve looked at in this study,” Dr. Pagani said. 

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In addition, the study’s findings may underestimate the effect of secondhand smoke in the household, she said, as the parents in their study may have underreported how much they smoked.