Sonographic quantitative analysis of the heart in the third trimester of gestation.

The fetal heart was studied with transabdominal sonography in 40 single normal pregnancies to analyze the increase of cardiac length and width (major longitudinal and transverse diameters of the heart) during the third trimester. Relationships between the cardiac data and fetal age, femur length and biparietal diameter (BPD) were explored by allometry and linear regression analysis. The length and width of the heart could be measured reproducibly in the 4-chamber view of the heart. This study verified that the heart grows very rapidly during the third trimester (positive allometry). The linear increase of the fetal heart shows a strong and significant correlation with the increase of both femur length and BPD. This suggests that non invasive analysis of cardiac data can be useful for prenatal detection of congenital heart disease or for the assessment of gestational age.