Effects of maternal tobacco smoking, sleeping position, and sleep state on arousal in healthy term infants

OBJECTIVES: To investigate whether a history of maternal tobacco smoking affected the maturation of arousal responses and whether sleeping position and infant age alters these relations. DESIGN: Healthy term infants (13 born to mothers who did not smoke and 11 to mothers who smoked during pregnancy) were studied using daytime polysomnography on three occasions: (a) two to three weeks after birth, (b) two to three months after birth, and (c) five to six months after birth. Multiple measurements of arousal threshold in response to air jet stimulation were made in both active sleep (AS) and quiet sleep (QS) when infants slept both prone and supine. RESULTS: Maternal smoking significantly elevated arousal threshold in QS when infants slept supine at 2-3 months of age (p<0.05). Infants of smoking mothers also had fewer spontaneous arousals from QS at 2-3 months in both prone (p<0.05) and supine (p<0.001) sleeping positions. In infants of non-smoking mothers, arousal thresholds were elevated in the prone position in AS at 2-3 months (p<0.01) and QS at 2-3 weeks (p<0.05) and 2-3 months (p<0.001). CONCLUSIONS: Maternal tobacco smoking significantly impairs both stimulus induced and spontaneous arousal from QS when infants sleep in the supine position, at the age when the incidence of sudden infant death syndrome is highest.