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Maternal cerebral blood flow changes in pregnancy
Gerda G Zeeman1, Mustapha Hatab, Diane M Twickler
1Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. g.g.zeeman@isala.nl
American Journal of Obstetrics and Gynecology
|October 31, 2003
Summary
Normal pregnancy causes a significant reduction in cerebral blood flow within large arteries, particularly the middle cerebral artery. This blood flow decrease is attributed to velocity changes, not vessel size alterations.
Area of Science:
- Neurology
- Obstetrics
- Medical Imaging
Background:
- Cerebral blood flow regulation during pregnancy is not fully understood.
- Pregnancy involves significant physiological adaptations affecting cardiovascular dynamics.
Purpose of the Study:
- To quantify changes in cerebral blood flow within major arteries during normal pregnancy.
- To assess if these changes correlate with gestational stage.
Main Methods:
- Velocity-encoded phase contrast magnetic resonance imaging (MRI) was used.
- Ten healthy pregnant volunteers were scanned at multiple gestational points and postpartum.
- Statistical analysis involved paired Student t tests to compare blood flow measurements.
Main Results:
- Cerebral blood flow in the middle cerebral artery decreased significantly by early pregnancy (14-16 weeks).
- Both middle and posterior cerebral arteries showed significant blood flow reductions in late pregnancy.
- No significant changes were observed in the posterior cerebral artery in early pregnancy.
Conclusions:
- Normal pregnancy is associated with an approximate 20% reduction in large cerebral artery blood flow.
- The reduction is primarily due to decreased blood velocity, with vessel area remaining constant.
- This may indicate widespread vasodilation in smaller cerebral arteries to maintain tissue-level perfusion.