Changes to the heart and blood vessels during pregnancy

During pregnancy, changes occur to the heart and blood vessels. These changes put extra stress on a woman’s body and require the heart to work harder. The following changes are normal during pregnancy. They help ensure that your baby will get enough oxygen and nutrients.

  • Increase in blood volume. During the first trimester, the amount of blood in the body increases by 40 to 50 percent and remains high.
  • Increase in cardiac output. Cardiac output refers to the amount of blood pumped by the heart each minute. During pregnancy, the output increases by 30 to 40 percent because of the increase in blood volume.
  • Increase in heart rate. It is normal for the heart rate to increase by 10 to 15 beats per minute during pregnancy.
  • Decrease in blood pressure. Blood pressure may decrease by 10 mmHg during pregnancy. This drop can be due to hormone changes and because there is more blood directed toward the uterus. Most of the time, the decrease does not cause symptoms and no treatment is needed. Your healthcare provider will check your blood pressure during your prenatal appointments and will tell you if blood pressure changes are cause for concern.

These changes cause fatigue (feeling overtired), shortness of breath and light-headedness. All of these symptoms are normal, but talk to your healthcare provider if you are concerned or have any questions.

If you have a heart condition you may need to take special precautions before and during pregnancy. Some heart conditions can increase a woman’s risk of complications. In addition, some women have heart or blood vessel conditions that are not identified until pregnancy. The mother’s health and well being are critical because if something bad happens to her, the baby is unlikely to survive.

Learn about our Cardio-Obstetrics Clinic

Reviewed 11/15