AbstractBackground:Alterations in left ventricular (LV) twist (torsion) and untwist have been described for a variety of physiologic and pathologic conditions. Little information is available regarding changes in these parameters during normal pregnancy.Hypothesis:Pregnancy is associated with significant changes in LV torsional mechanics.Methods:Left ventricular twist and untwist was measured in 32 pregnant females (mean gestation 199 ± 48 d) and 23 nonpregnant controls using speckle‐tracking echocardiography.Results:Left ventricular ejection fraction (68 ± 5% vs 66 ± 5%) was similar between the groups (P not significant). There was a significant increase in peak LV twist from nonpregnant controls (9.4 ± 3.7 degrees) to second‐trimester (12.0 ± 4.2 degrees) and third‐trimester subjects (12.6 ± 5.9 degrees, all P<0.05). Peak LV twist velocity was also increased in second‐ and third‐trimester groups compared with controls (94 ± 24 degrees/sec and 93 ± 30 vs 64 ± 21 degrees/sec, respectively, both P<0.05). Both peak untwist velocity and time to peak untwist velocity were not significantly different between groups (P not significant). Multiple regression analysis indicate that only systolic blood pressure (r = 0.394, P = 0.005) was an independent predictor for increased LV torsion.Conclusions:There are significant changes in LV torsional indices during the course of pregnancy, whereas untwist parameters remain unchanged. Blood pressure is independently associated with increased torsion during pregnancy. © 2011 Wiley Periodicals, Inc.The authors have no funding, financial relationships, or conflicts of interest to disclose.