Chronic effects of maternal smoking on pulse waves in the fetal aorta

OBJECTIVE: In order to evaluate the impact of maternal smoking on arterial stiffness in utero, pulse wave characteristics in the fetal aorta were investigated. A prospective clinical study was made of 34 smoking and 34 non-smoking healthy volunteers with uncomplicated pregnancies at 31-40 weeks of gestation. METHODS: The mechanical properties of the fetal thoracic aorta were assessed by an ultrasonic phase-locking echo-tracking system. For each fetus with a smoking mother, a non-smoking control matched for gestational and maternal age was monitored. Women with later appearing pregnancy complications were excluded. Pulse wave velocity (PWV), maximum diameter in systole (Ds), end-diastolic diameter (Dd), pulse amplitude (DeltaD), and maximum incremental velocity (MIV) in the fetal aorta were measured and analyzed in relation to maternal smoking and gestational age. RESULTS: Results were computed on fetuses of 32 smokers and 30 non-smokers. PWV increased with gestational age in smokers (corr. coeff. 0.49, p < 0.006) but not in non-smokers (corr. coeff. -0.12). MIV did not change in smokers (corr. coeff. -0.15) but increased in non-smokers (corr. coeff. 0.40, p < 0.03). Differences in regression lines between the groups regarding PWV and MIV were significant (p < 0.02 for both). CONCLUSIONS: Maternal smoking seems to promote the stiffening of the fetal aorta during gestation.