We assessed the relation between symptoms and cardiac arrhythmias in 110 consecutive pregnant patients without evidence of heart disease referred for evaluation of palpitations, dizziness, and syncope (study group) and in 52 consecutive patients referred for evaluation of an asymptomatic functional precordial murmur (control group). Both groups had a high incidence of arrhythmias on Holter monitoring with atrial premature complexes (APCs) of 56% in the study group and 58% in the control group, > 100 APCs in 7% and 4% of the patients, respectively, and isolated ventricular premature complexes (VPCs) in 59% and 50%, respectively. The number of isolated VPCs was higher and > 50 VPCs/hour were seen in more patients in the study group (3,235 +/- 6,397 vs 678 +/- 3,358 beats/24 hours p < 0.05 and 22% vs 2% p = 0.03). Similarly, the incidence of multifocal VPCs was higher in the study patients (12% vs 2%, p < 0.05). There was no correlation between the incidence of both VPCs or APCs and symptoms, and only 10% of symptomatic episodes were accompanied by the presence of arrhythmias. Repeated Holter monitoring 6 weeks postpartum in 9 women with multiple premature contractions during pregnancy (9,073 +/- 9,210/24 hours) showed a substantial reduction to 1,345 +/- 1,997/24 hours (p < 0.05). Thus, this study confirms an increased incidence of arrhythmias during normal pregnancy. These arrhythmias consist mostly of APCs and VPCs. The number of simple and multifocal VPCs is higher in patients presenting with symptoms of palpitations, dizziness, or syncope; however, there is no correlation between the incidence of arrhythmias and symptoms, and only 10% of symptomatic episodes were accompanied by the presence of arrhythmias.