Objective: The aim of the study was to assess the left ventricular (LV) synchronicity in pregnant women and to identify the main determinants of LV dyssynchrony in asymptomatic pregnant women. Methods: One hundred sixty-seven pregnant women consecutively and 48 age-matched nonpregnant controls were enrolled. For the assessment of LV systolic dyssynchrony, the standard deviation of the time from QRS onset to peak systolic (Tps-LV- standard deviation [SD]) velocity and the maximal difference of the time from QRS onset to peak systolic velocity (Tps-LV) from 12 segments at the apical views. For the LV diastolic dyssynchrony, the standard deviation of the time from QRS onset to peak diastolic (Tpe-LV- SD) velocity and the maximal difference of the time from QRS onset to peak diastolic velocity (Tpe-LV) were calculated. Results: Both systolic and diastolic dyssynchrony indexes were significantly higher in pregnant women than in the normal controls (Tps-LV; P<.01, Tps-LV- SD; P<.03, Tpe-LV, P<.05 and Tpe-LV- SD; P<.02). A total of 28 (16.8%) of the pregnant women had a dyssynchrony index above the accepted value for LV dyssynchrony (>34.4 msec). There was a significant correlation between LV dyssynchrony indexes with, multiparty, multifetal pregnancies, systolic blood pressure in pregnant women with LV dyssynchrony. Additionally LV dyssynchrony was significantly associated with elevated E/e” and brain natriuretic peptide (BNP). Conclusions: Both systolic synchronicity and diastolic synchronicity were affected in pregnant women compared to nonpregnant women. LV dyssynchrony was significantly correlated with age, multiparity, and BNP level. Early detectable changes in systolic and diastolic synchrony may be present in pregnant women at higher risk of peripartum cardiomyopathy.