[Increase in weight and changes in the heart weight/body weight quotient of the embryonic heart in early pregnancy]

Abstract

On the basis of measuring heart weight and body weight of 73 embryos it is shown that there is a close linear correlation between growth of the heart, increase of heart weight and body weight and age of pregnancy. The increase in heart weight, however, is not proportional to that of the increase in body weight during intrauterine development. There is a considerable shift in the heart weight/body weight ratio (i.e. a change in the cardio-fetal index: (formula; see text) In early pregnancy (5-7th weeks) the cardio-fetal index varies from 1.5 to 2.5 and in the course of pregnancy it decreases gradually. In the 12th-14th weeks it falls below 1, and following the 14th week it stays on a relatively constant level of 0.5-0.8. In early embryonic phase heart weight in relation to body weight is 2-5 times bigger than in the period following the 14th week. The significance of these findings is discussed.