Morphometry of the human heart in the second and third trimesters of gestation.

The growth of the heart was studied in 56 human fetuses ranging from 14 to 38 weeks (23 female and 33 male) using the following measurements: cardiac length and width, aortic and pulmonary artery internal diameters, right and left anterior ventricular wall thickness. Relationships between the fetal cardiac data and crown-rump length were explored by allometry and linear regression analysis. The present study confirmed that the heart increases with high growth rates and positive allometry during prenatal life. Statistically different growth rates were found comparing female with male fetuses (sexual dimorphism): (a) in the third trimester (P < 0.001, except for the cardiac length and the left ventricular wall thickness), (b) considering fetuses of the second and third trimesters together (only for cardiac width, P = 0.0015). In these circumstances the female fetuses had the greatest growth rates. The length and the width of the heart are diameters easily obtained in the ultrasonographic four-chamber view of the heart in the last two trimesters of gestation. Therefore, these data can be analyzed by non-invasive methods and are useful for prenatal detection of congenital heart disease.