title: Changes in Doppler flow velocity waveforms and fetal size at 20 weeks gestation among cigarette smokers.
abstract: OBJECTIVE
  To compare umbilical and uterine artery Doppler waveforms and fetal size at 20 weeks between smokers and nonsmokers.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Auckland, New Zealand and Adelaide, Australia.
  
  
  METHODS
  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.
  
  
  METHODS
  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 < 0.0001] and mean uterine RI [0.59 (0.09) versus 0.56 (0.10), P < 0.0001]. They were twice as likely to have an abnormal umbilical Doppler at 20 weeks compared with nonsmokers [n = 35 (14.6%) versus n = 156 (7.2%), OR 2.21, 95% CI 1.49-3.27]. This effect remained significant after adjusting for age, ethnicity, marital status, employment and BMI (adjusted OR 1.62, 95% CI 1.03-2.54). Smokers were more likely to have an abnormal mean uterine RI [n = 33 (13.7%) versus n = 198 (9.2%), OR 1.57, 95% CI 1.06-2.33], but this association was not significant after adjusting for confounders. Fetuses of women who smoked had a small reduction in femur length and estimated weight compared with nonsmokers.
  
  
  CONCLUSIONS
  At 20 weeks' gestation, women who smoke have higher umbilical artery RI, a surrogate measure for an abnormal placental villous vascular tree. This may contribute to later fetal growth restriction among smokers. Further research is needed to explore the clinical significance of these findings.
authors: Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, School of Population Health, University of Auckland, Auckland, New Zealand.
authors: E M
authors: EM
authors: Kho
authors: R A
authors: RA
authors: North
authors: E
authors: E
authors: Chan
authors: P R
authors: PR
authors: Stone
authors: G A
authors: GA
authors: Dekker
authors: L M E
authors: LM
authors: McCowan
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D049628:Body Size; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D033401:Microscopy, Acoustic; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D012907:Smoking / Q000503:physiopathology*; D018608:Ultrasonography, Doppler / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*; D014655:Vascular Resistance / Q000502:physiology; D055815:Young Adult