Smoking and buccally administered nicotine. Acute effect on uterine and umbilical artery Doppler flow velocity waveforms

The effects of maternal smoking and buccal nicotine exposure on uterine and umbilical artery blood flow velocity waveforms were studied in 47 healthy women during late pregnancy. Systolic:diastolic ratios of recorded waveforms were calculated before and after each woman smoked one cigarette containing 1.2 mg of nicotine. The same protocol was followed at a subsequent clinic visit, when each woman chewed a piece of nicotine polacrilex containing 2 mg of nicotine. No significant changes could be induced in either nonsmokers or prior smokers, nor were any significant changes measured in the uterine vessels of any patient subgroup. A significant decrease (P less than .01) in umbilical artery diastolic blood flow velocities was measured after smoking in all habitual smokers after chewing nicotine polacrilex and in those who smoked greater than 10 cigarettes per day (P less than .05). All the measured changes returned to baseline levels by 10 minutes after cessation of exposure. Similar changes in the umbilical artery flow velocity waveforms after exposure to a cigarette and nicotine polacrilex implicated nicotine as a probable cause. Failure to observe significant changes except in habitually smoking women suggests a receptor-mediated response. The finding of altered umbilical artery flow velocity waveforms in the absence of demonstrable changes in the uterine vessels indicates a direct toxic effect of maternal nicotine exposure on the fetal cardiovascular system.