Pregnancy and labor, though a physiological and natural time in a woman’s life, are associated with many changes to the woman’s body. The overall blood volume, cardiac output and heart rate of a pregnant woman differ significantly from pre-pregnancy time. This again has a significant effect on the electrical activity of the heart. Abnormal electric activity of the heart might be confused with an ongoing or commencing heart disease. Moreover, pregnancy, labour and especially the post partum period are also known to increase the risk of cardiac events including arrhythmia, myocardial infarction or even sudden cardiac death, especially in women with a present cardiac disease like LQTS (Long QT Syndrome). In order to reduce the occurrence of adverse cardiac events and enable their early detection and diagnosis, there is a need for a more thorough understanding of electrocardiographic changes occurring during pregnancy. Unfortunately, data regarding changes of the electric activity of the heart during pregnancy are scarce. The aim of this work is to give an outline on the electric activity changes of the heart of a pregnant woman. The available data confirm that intense changes in the cardiovascular system caused by pregnancy strongly affect the electrical activity of the heart.