Final answer:
During pregnancy, the increase in blood volume, rise in pulse and blood pressure, compression of blood vessels by the uterus, and contractions during labor are all cardiovascular changes that can cause faintness and syncope.
Step-by-step explanation:
During pregnancy, there are several cardiovascular changes that can cause faintness and syncope. One of these is the increase in blood volume, which helps to manage the demands of fetal nourishment and waste removal. The pulse and blood pressure also rise moderately, and the compression of blood vessels by the growing uterus hampers venous return, leading to conditions like varicose veins. Additionally, contractions during labor can result in reduced oxygenated blood flow to the fetus, causing fetal distress.