Changes in Doppler flow velocity waveforms and fetal size at 20 weeks gestation among cigarette smokers

Objectives To compare umbilical and uterine artery Doppler waveforms and fetal size at 20 weeks between smokers and nonsmokers. Design Prospective cohort study. Setting Auckland, New Zealand and Adelaide, Australia. Population Nulliparous participants in the Screening for Pregnancy Endpoints (SCOPE) study. Methods Self‐reported smoking status was determined at 15 ± 1 weeks’ gestation. At the 20 ± 1 week anatomy scan, uterine and umbilical Doppler resistance indices (RI) and fetal measurements were compared between smokers and nonsmokers. Main outcomes measures Umbilical and mean uterine artery Doppler RI values, abnormal umbilical and uterine Doppler (RI > 90th centile) and fetal biometry. Results Among the 2459 women, 248 (10%) were smokers. Smokers had higher umbilical RI [0.75 (SD 0.06) versus 0.73 (0.06), P