Throughout your pregnancy you might feel your heart pounding harder than usual, as you already know, blood volume steadily increases to accommodate the body’s increasing need for oxygen and nourishment. By the third trimester you have forty-five percent more blood than you started with. Your heart has to work harder to pump this extra fluid: your heart rate increases by around ten beats per minute and the heart pumps about thirty percent more blood with each beat. These changes peak during mid-pregnancy when you may be able to feel your heart working harder; many women feel “heart-pounding” sensations during the second half of pregnancy, especially when they exercise or change position suddenly.
The heart’s occasional pounding is a normal response to the major circulatory changes that take place during pregnancy. Yet, it is also a signal that your heart, at the moment, is working too hard. The more fit you are, the better your heart adjusts to the extra demands of pregnancy. If the pounding increases noticeably during exercise, slow down. Rise from lying to sitting, or from sitting to standing more slowly. These heart-pounding sensations will disappear within a few weeks after birth, as your heart rate slows and your circulatory system returns to its pre-pregnant state.