During pregnancy, a number of physiological changes occur which can predispose to arrhythmias. Symptoms can range from asymptomatic states to shortage of breath or palpitations, as also found in non-pregnant patients. Treatment is currently subject of scientific studies and there are different recommendations proposed by the main scientific societies. Hence, doubts and disputes raise when facing each case, firstly due to the concern about maternal and fetal well-being, and secondly to the possible complications inherent in the management of each drug. Clinical case: A case of a pregnant woman with 37 weeks of pregnancy, who presented supraventricular tachycardia without hemodynamic instability, is presented. According to the Spanish Society of Cardiology, guidelines an intravenous adenosine treatment was applied in a first instance. Since no reversion of the arrhythmic state was observed, the conduction of an electric countershock and termination of pregnancy by elective caesarean section was performed in agreement among Obstetrics, Intensive Care, Emergency Care and Pediatric Services.