Acute effects of maternal smoking on fetal breathing and movements.

The acute effects of cigarette smoking on fetal breathing movements and fetal movements were determined with a realtime ultrasound system in 10 healthy habitually smoking women in late gestation. The study was carried out for 1 hour before and 1 hour after the woman smoked a single cigarette. The maternal blood glucose concentration was maintained at a raised postprandial level through the study. After smoking a significant increase in the rate of fetal breathing movements (P<.05) appeared together with a reduction in the short time variability of the breath-to-breath intervals (P<.05). The number of epochs without fetal breathing movements or fetal trunk and limb movements increased after smoking (P<.05) indicating a change in the spacing of these fetal activities. The increased breathing rate and number of apneic epochs were both correlated to maternal nicotine levels. These observations suggest an acute influence on the fetal behavioral state of maternal smoking. (authors)