Blood Pressure and Heart Rate Variability in Preschool Children Exposed to Smokeless Tobacco in Fetal Life

Background Maternal smoking during pregnancy has been associated with higher blood pressure and autonomic imbalance in the offspring. However, it has been difficult to determine the selective prenatal and postnatal contributions as children frequently have been exposed to smoking both before and after birth. The specific role of nicotine is also unclear. We aimed to determine whether exclusive prenatal exposure to nicotine from maternal use of smokeless tobacco (Swedish snus) in pregnancy was associated with blood pressure and autonomic heart rate control in their children. Methods and Results We measured oscillometric blood pressures in forty 5- to 6-year-old children with snus exposure in fetal life (n=21) and in tobacco-free controls (n=19). Taking the child's age and height into account, snus-exposed children had 4.2 (95% CI, 0.2-8.1) mm Hg higher systolic blood pressure than controls (P=0.038). The corresponding sex-, age-, and height-standardized systolic blood pressure centiles were 61 and 46 (95% CI of the difference, 2-28) (P=0.029). Heart rate variability was tested in 30 of the children. The spectral heart rate variability variable low-frequency/high-frequency ratio was higher (median, 0.69; interquartile range, 0.45-1.21) in snus-exposed children than in controls (median, 0.21; interquartile range, 0.32-0.57; P=0.034). Conclusions Prenatal snus exposure was associated with higher systolic blood pressure and altered heart rate variability at 6 years of age. These findings may indicate adverse prenatal programming of nicotine, but implications for cardiovascular health in later life remain to be studied. Meanwhile, women should be recommended to abstain from all types of tobacco and nicotine products during pregnancy.