Pregnancy puts an extra strain on the heart, just as it does other parts of the body. Carrying a child requires the heart to work harder than normal as it supplies blood to the uterus. The following changes to the heart and blood vessels during pregnancy are common:
Increase in blood volume
The amount of blood in the body rises as much as 50 percent and remains high until baby is born.
Increase in heart rate
It is normal for the heart rate to increase about 25 percent faster than usual during pregnancy.