What triggers the baroreceptors to respond during cord compression?

The correct answer highlights the role of baroreceptors, which are specialized sensors in the body that detect changes in blood pressure. During cord compression, the resulting physiological stress leads to a series of responses. When the umbilical cord is compressed, it can cause a decrease in blood flow to the fetal circulation, which can subsequently lead to an elevation in fetal blood pressure due to the body's compensatory mechanisms to maintain perfusion to vital organs.

As the baroreceptors sense this increased fetal blood pressure, they respond by initiating reflexes to help regulate and stabilize the cardiovascular system. These reflexes can include adjusting heart rate and vascular tone. While changes in fetal heart rate and oxygen supply are important factors during cord compression, the primary trigger for the baroreceptors in this scenario is the increase in fetal blood pressure. This underscores the body’s intricate feedback systems aimed at protecting fetal well-being during stress situations like cord compression.