Parental smoking was an independent risk factor for elevated systolic blood pressure in 4,236 preschool children who were part of a blood pressure screening project in Germany.
Current smoking was reported by 29% of fathers and 21% of mothers of the children in the study, and both parents reported smoking in 12% of cases. Children who had a parent who was a smoker were significantly more likely to have higher systolic blood pressure, even after adjusting for risk factors such as body mass index, parental hypertension, and birth weight, Dr. Giacomo D. Simonetti of the University of Heidelberg (Germany), and his colleagues reported online in Circulation.
Having a parent who was a smoker increased the likelihood of having a systolic blood pressure in the top 15% of the population by 21%, the investigators found (Circulation 2011 Jan. 25 [doi:10.1161/circulationaha.110.958769]).
Other significant correlates of systolic blood pressure were gender, height, BMI, birth weight, gestational hypertension, and parental hypertension. Correlates of diastolic blood pressure were gender, height, BMI, birth weight, and parental hypertension, the investigators said.
"Moreover, systolic and diastolic blood pressure progressively increased with the cumulative number of parent-related risk factors (parental obesity, hypertension, and smoking)," they noted.
The absolute difference in blood pressure between children with no risk factors and those with three risk factors was 3.2 mm Hg for systolic blood pressure, and 2.9 mm Hg for diastolic blood pressure, which corresponds to nearly half of a standard deviation of the blood pressure distribution in the total population, the investigators noted.
Children in the study were aged 4.0 to 7.5 years (mean 5.7 years), and were evaluated between February 2007 and October 2008. Blood pressure was measured in conjunction with a family health and lifestyle survey.
The findings demonstrate that the multifactorial dependency of blood pressure on various influences – including familial, prenatal, and environmental influences – are evident even in early childhood, they said, adding that a unique finding of this study is "the novel evidence for a BP-raising effect of environmental nicotine exposure in children as young as 4-5 years of age."
Although the effects of active and passive tobacco exposure on cardiovascular functions in adults are well known and have been widely demonstrated, the effects of passive tobacco smoke exposure on childhood blood pressure have not been reported previously.
Of note, maternal – but not paternal – cigarette consumption had a quantitative relationship with childhood blood pressure in this study, which may be a result of more at-home smoking among mothers, vs. at-work smoking among fathers. Also, the effect size of passive smoking was higher in boys than in girls, raising the question of whether the sex-preferential susceptibility of adolescent and adult males to cardiovascular risk factors also is present in younger children. This may be an interesting field of future research, the investigators suggested.
The findings of this study underscore the potential benefits of implementing strictly smoke-free environments, particularly at home. This may help preserve cardiovascular health in both adults and children, the researchers said.
The potential benefits of a smoke-free environment is supported by several lines of reasoning, including the fact that smoke-free environments have been shown to decrease cardiovascular mortality in nonsmokers, that childhood blood pressure consistently tracks into adult life, and that children whose parents smoke are more likely to become smokers themselves.
Indeed, "comprehensive interventions that seek to reduce the cardiovascular risk burden early in life by promoting lifestyle changes in all family members may prove essential for lowering the cardiovascular disease risk of future generations," the investigators concluded.
This study was funded by the Manfred-Lautenschläger Stiftung, the Reimann-Dubbers Stiftung, the Dietmar-Hopp Stiftung, and the Swiss Society of Hypertension AstraZeneca scholarship awarded to Dr. Simonetti. The investigators reported having no other disclosures.