EFFECTS OF PREGNANCY ON THE ELECTROCARDIOGRAM IN HEALTHY-SUBJECTS DURING STRENUOUS EXERCISE

OBJECTIVE: Our purpose was to examine the nature and the frequency of electrocardiographic changes at rest and after bicycle exercise in ear ly and late gestation compared with a group of nonpregnant subjects. S TUDY DESIGN: Thirty-nine pregnant subjects had electrically braked bic ycle exercise early and late in gestation. Eight nonpregnant subjects served as controls. Twelve-lead electrocardiograms were obtained durin g rest, exercise, and recovery. All electrocardiograms were analyzed b y a cardiologist blinded to subject group and stage of the pregnancy. Data were analyzed by analysis of variance for repeated measures, and contingency tables were used to compare findings at rest and during ex ercise between the time periods. A p value < 0.05 was considered signi ficant. RESULTS: T-wave inversion in V-2, was more frequent in the pre gnant than the nonpregnant subjects (p < 0.01). Subjects ''late'' in p regnancy had significantly fewer Q waves in II, III, and aVF than the nonpregnant group did. With exercise the time to onset of maximum ST d epression was significantly shorter during pregnancy. CONCLUSION: Alth ough minor electrocardiographic changes were found at rest and during exercise between the two groups, these should be considered normal unl ess associated with significant symptoms.