title: Maternal cerebral blood flow during normal pregnancy: a cross-sectional study.
abstract: OBJECTIVE
  Pregnancy is associated with substantial changes in the maternal circulatory physiology. Our aim was to investigate maternal cerebral blood flow (CBF) during normal pregnancies.
  
  
  METHODS
  We prospectively measured maternal CBF in 210 low-risk pregnant women at different gestational ages, and in 15 nonpregnant women. CBF was assessed by measuring blood flow volume in the internal carotid artery (ICA) by dual-beam angle-independent digital Doppler ultrasound.
  
  
  RESULTS
  ICA blood flow volume increased during pregnancy from 318 mL/min ± 40.6 mL/min in the first trimester to 382.1 mL/min ± 50.0 mL/min during the third trimester, corresponding to CBF values of 44.4 and 51.8 mL/min(-1)/100 g(-1), respectively (P < .0001). CBF changes were associated with progressive decrease in cerebral vascular resistance and moderate increase in ICA diameter.
  
  
  CONCLUSIONS
  Maternal CBF is gradually increasing during normal pregnancy. Vasorelaxing impact of estrogens and other factors on cerebral vessels may explain the changes in CBF during pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, University of Toronto, 60 Grosvenor Street, Toronto, Ontario, Canada. ori.nevo@sunnybrook.ca
authors.forename: Ori
authors.initials: O
authors.lastname: Nevo
authors.forename: Jean F
authors.initials: JF
authors.lastname: Soustiel
authors.forename: Israel
authors.initials: I
authors.lastname: Thaler
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D012016:Reference Values; D014463:Ultrasonography; D014655:Vascular Resistance / Q000502:physiology