Effects of maternal cigarette smoking on ultrasonic measurements of fetal growth and on Doppler flow velocity waveforms.

Serial ultrasound biometry and Doppler flow velocity waveform analysis were used to measure the effects of maternal smoking in a prospective study of 535 pregnancies. Smoking was associated with significant reductions in maternal weight gain, birthweights and placental weights. Decreased fetal biparietal diameter measurements were observed in pregnancies of smoking women; this effect was maximal at 24 weeks' gestation, was restricted to male fetuses and was not associated with altered head circumferences after birth. Umbilical artery and uteroplacental systolic/diastolic ratios were similar in pregnancies of smoking and non-smoking women, indicating that the effects of smoking on placental vascular resistance are periodic rather than continuous. The findings of this study confirm the need for studies of fetal growth to include prenatal measurements obtained by high resolution ultrasound imaging, rather than relying on findings obtainable by examination of the infant after birth.