Background: Cardiovascular changes of pregnancy are well-known; however, parameters for accurately assessing these changes have not been refined as measurement tools have advanced. We sought to examine the range of echocardiographic parameters during normal pregnancy using current echocardiographic imaging modalities. Methods: We performed a retrospective analysis of normal echocardiograms in 121 women (97 pregnant, 24 non-pregnant) without evidence of cardiovascular disease. Linear, area, and Doppler fl ow measurements were made of commonly reviewed cardiac structures. Height-indexed measurements were compared between pregnant women and controls and between trimesters of pregnancy. Results: Compared to non-pregnant patients, all four cardiac chambers showed significant enlargement in the pregnant patients. The left atrium was the first chamber to enlarge. LV mass also increased in the third trimester (134.5 ± 31 vs. 112.3 ± 28.2 g, P & lt; 0.01), with preservation of LV mass to volume ratio. LV ejection fraction was significantly larger (68% vs. 63%, P < 0.036) in the second trimester patients, but decreased into the third trimester (64.1% & plusmn; 6.8%, P < 0.006). When pulmonary artery systolic pressure (PASP) was calculated from the pulmonary artery acceleration time, observed pressures were significantly greater in the third trimester than second trimester (40.1 ± 10.3 vs. 45.5 ± 10.1 mm Hg, P = 0.029). PASP calculated conventionally from tricuspid regurgitation gradient did not show similar significance. There was no significant change in diastolic parameters throughout pregnancy. Conclusion: This study provides data on echocardiographic parameters during normal pregnancy and is one of the largest sample sizes in the literature. The results will contribute to the current literature by helping to distinguish between normal and abnormal echocardiograms during pregnancy.