Placenta and uteroplacental perfusion

The placenta is a complex and changing organ necessary for normal fetal growth and development and for maintenance of a healthy pregnancy. It has three major functions: a protective function of the fetus, an endocrine function, and a metabolic function. The main functional unit of the placenta is the chorionic villous, responsible for the majority of the fetal–maternal exchanges. Migration of trophoblastic cells induces a remodelling of the uterine arteries, with vasodilatated and compliant vessels, unresponsive to maternal vasomotor control. Therefore, any significant change in maternal blood pressure, in particular in the context of general or regional anaesthesia, can directly impact on uteroplacental perfusion. Most anaesthetic drugs cross the placental barrier, but without significant consequences on the fetal well-being.