Maternal cerebral blood flow during normal pregnancy: a cross-sectional study.
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.
Nevo
Ori
O
Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, University of Toronto, 60 Grosvenor Street, Toronto, Ontario, Canada. ori.nevo@sunnybrook.ca
Soustiel
Jean F
JF
Thaler
Israel
I
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