Pregnancy and Your Heart

Written by: Dr. Paige Partridge

During pregnancy, our bodies change in many remarkable ways.  As the fetus grows and the uterus expands, we often document with pictures our ever-enlarging profile.  Internally, there are changes occurring that we cannot see but are vitally important to the health and progress of the pregnancy.

Changes in the cardiovascular system begin as early as the 4th week of pregnancy.  There is an increase in the red blood cells which assists our bodies with the increasing requirement for oxygen.  The maternal heart rate increases and the size of the heart increases, as well. The cardiac output, which is a measure of the heart rate and the volume of blood, increases 30-50% above the baseline.  This increase in volume provides reserve against the blood loss during delivery which can range between 300mL and 1000mL, based on either a vaginal delivery or a cesarean section. 

Blood pressure falls early in pregnancy and then gradually increases in the third trimester back to normal values.  In the case of preeclampsia, however, the blood pressure rises to abnormally elevated levels along with other findings, such as protein in the urine, swelling, visual changes, and headaches.

Heart palpitations occur frequently during pregnancy as do heart murmurs.  Mild shortness of breath tends to occur in the second and third trimesters.  Most commonly, these findings are normal. These symptoms, however, occasionally warrant an evaluation by a cardiologist.  During delivery, there are also significant hemodynamic changes due to exertion, pain, contractions and bleeding.

Cardiovascular events account for the highest percentage of maternal deaths.  Maintaining a healthy weight throughout the pregnancy creates less physical strain on the heart.  Focusing on a healthy diet and regular exercise contributes to a normal blood pressure. Wearing compression socks on long trips will improve blood flow and decrease the risk of a blood clot.

If you are experiencing symptoms of palpitations, shortness of breath or chest pain, it is important to make your obstetrician aware so that he/she can evaluate appropriately and consult a cardiologist if needed.