[Low blood pressure in pregnancy]

There has been a controversial discussion for decades about the significance of low blood pressure during pregnancy. This review should answer the question, whether low blood pressure itself or the decrease in blood pressure on standing have a negative effect on pregnant women. In addition, we will focus on physiologic and pathophysiologic pregnancy related mechanisms of changes in blood pressure. Subjective symptoms occur more frequently with low blood pressure, however, they disappear at the end of pregnancy. Physiologically, blood pressure decreases towards midpregnancy and rises to preconceptional values at term. Birthweight was directly related to the magnitude and direction of the pressor response on standing in late pregnancy but not to the low blood pressure at rest itself. There is no causal association between low blood pressure and poor perinatal outcomes. It is only an accompanied symptom for other risks in pregnancy. There is a direct relationship between the change in mean arterial blood pressure in standing position and birthweight during late pregnancy. Patients whose pressure falls on standing have the lightest babies.