To determine the influence of maternal smoking on autonomic nervous system
in healthy infants, 36 infants were recorded polygraphically for one night.
Their mothers were defined, according to their smoking frequency during pr
egnancy, as "nonsmokers" (no cigarettes smoked during pregnancy) or "smoker
s" (10 or more cigarettes per day). The infants had a median postnatal age
of 10.5 wk (range 6 to 16 wk); 18 were born to nonsmokers, and 18 to smoker
s. During the whole night, spectral analyses of heart rate (HR) were evalua
ted as a function of sleep stages. Two major peaks were recognizable: a low
-frequency component (LF) related to sympathetic and parasympathetic activi
ties and a high-frequency component (HF) reflecting parasympathetic tonus.
The ratio of LF/HF powers was calculated as an index of sympathovagal inter
action. In REM sleep, "smokers" infants were characterized by significantly
lower HF powers and normalized HF powers, and higher LF/HF ratios than "no
nsmokers." The finding did not reach statistical significance in NREM sleep
. In conclusion, maternal smoking induced changes in autonomic control and
maturation in infants. These effects of cigarette smoke exposure can be add
ed to those already reported and offer additional evidence for counseling m
others to stop smoking.