Pregnancy can be hard on your heart. During pregnancy, changes occur to the heart and blood vessels that stress a woman's body and increase the workload of the heart. Dr. Richard Krasuski, a cardiologist at Cleveland Clinic who treats pregnant women, calls  pregnancy the "ultimate stress test."

"Pregnancy is a remarkable time," he said. "If you think about all the changes that occur to the body, you know, you have another growing being inside you, so you're growing all of these additional blood vessels. Your heart is pumping much harder, it's working much harder. So, really, it's the ultimate form of stress testing."

During the first trimester, the volume of blood increases by 40 to 50 percent and remains high throughout pregnancy. The amount of blood that is pumped by the heart each minute increases 30 to 40 percent.

It's also normal for the heart rate to increase by 10 to 15 beats per minute during pregnancy and in some women, for blood pressure to decrease because of hormone changes.

Krasuski says women with heart problems don't necessarily have to avoid getting pregnant; they just have to have a good plan.

"So, if you have a history of heart disease, whether it was something you were born with or something that you developed it's very important that you see both, potentially a cardiologist and an obstetrician, just to be able to plan properly," he explained.

Krasuski says since so many women are having babies later in life, it is not uncommon to see a pregnant woman who has heart disease.