Cerebral hemodynamics in normal and complicated pregnancy

During pregnancy, approximately 6-25% of women are diagnosed with some form of hypertension. These disorders are among the leading causes of maternal mortality and severe morbidity. While multiple maternal organs can be affected, cerebral involvement is one of the most feared complications as it can lead to death or significant short- or long-term morbidity. The pathophysiology of these cerebrovascular complications remains poorly understood, but it is thought that the blood vessels in the brain malfunction. Normally, the blood flow in the brain does not change despite changes in blood pressure. This is called ‘cerebral autoregulation’. This mechanism protect the brain from bleeding when the blood pressure is high, and protects from fainting when the blood pressure is low. In this thesis, we show that in normal pregnancy, more blood flows to the posterior part of the brain. This may explain why women with preeclampsia have symptoms, which mainly originate from the posterior part of the brain, such as the vision. The cerebral autoregulation improves when a women is pregnant, but is worsened in pregnant women with preeclampsia or chronic hypertension. Autoregulation in pregnancy is not affected by diabetes, overweight or pregnancy induced hypertension. Breath holding also causes a reaction of the brain vessel. This reaction is different in preeclampsia from healthy pregnant women. This also shows that these vessels malfunction. Finally, in this thesis we show that examination of the brain vessels may be used as a screening tool to identify those women who are at risk for developing preeclampsia.