Prenatal exposure to cigarette smoking is associated with a decrease in arousal in infants

Objective: Sudden infant death syndrome has been related to both exposure t o prenatal cigarette smoke and impaired arousability from sleep. We evaluat ed whether healthy infants born to mothers who smoked during pregnancy had higher auditory arousal thresholds than those born to mothers who did not s moke and whether the effects of smoking occurred before birth. Study design: Twenty-six newborns were studied with polygraphic recordings for 1 night: 13 were born to mothers who did not smoke, and 13 were born to mothers who smoked (>9 cigarettes per day). Other infants with a median po stnatal age of 12 weeks were also studied, 21 born to nonsmoking mothers an d 21 born to smoking mothers. White noise of increasing intensity was admin istered during rapid eye movement sleep to evaluate arousal and awakening t hresholds. Results: More intense auditory stimuli were needed to induce arousals in ne wborns (P = .002) and infants (P = .044) of smokers than in infants of nons mokers. Behavioral awakening occurred significantly less frequently in the newborns of smokers (P = .002) than of nonsmokers. Conclusions: Newborns and infants born to smoking mothers had higher arousa l thresholds to auditory challenges than those born to nonsmoking mothers. The impact of exposure to cigarette smoke occurred before birth.