The cardiac output (CO) and cardiac index (CI) were examined by echocardiography throughout pregnancy and 1 month of puerperium and the results were compared with fetal growth as determined by birth weight. The results are as follows. The changes in CO and CI during the pregnancy and puerperium of normal pregnant women (n = 48) were similar in all subjects, and reached the maximum at the 24th-31st week's of gestation. On the 5th day of puerperium, the CO and CI values were almost the same as those obtained at the 32nd-40th weeks of gestation, and after 1 month of puerperium the values were same as those obtained in the non-pregnant period. The CO and CI of HFD child-bearing group (n = 8), AFD child-bearing group (n = 30) and LFD child-bearing group (n = 10) were compared. The CO and CI values for the LFD group were lower than those for AFD group; particularly, significant differences (p less than 0.05) were observed in 24th-31st weeks and 32nd-40th weeks of gestation. The CO and CI values of HFD group tend to be higher than those for AFD group, but there is no statistical significance between the two groups. The birth weight correlated to the rate of increase in CO and CI during pregnancy with coefficients of correlation of 0.56 (p less than 0.05) and 0.54 (p less than 0.05), respectively. The rate indicates the ratio of maximum values of CO and CI obtained during pregnancy to the values after 1 month of puerperium, which have been shown to be consistent with those during the non-pregnant period. A significant correlation (r = 0.54, p less than 0.05) was found between placenta weight and birth weight. The correlations between placental weight and the rate of increase in CO and CI were also significant with coefficients of correlation of 0.40 (p less than 0.05), and 0.38 (p less than 0.05), respectively.