Antenatal ultrasonography is noninvasive and done on routine basis in our institution. A four chamber view of the fetal heart is done as a part of regular sonographic examination of the fetus. Most cases of congenital heart disease are of structural rather than functional origin. Aims & objectives: To determine cardiac length (major longitudinal diameter) of the fetal heart during the third trimester of pregnancy. To evaluate the relationship between fetal heart dimensions obtained from sonography (cardiac length) and Gestational age (weeks) Biparietal diameter (mm) Femur length (mm) & abdominal circumference. Materials & Methods: The fetal heart was studied with transabdominal sonography in 132 single normal pregnancies in third trimester Measurement of cardiac length ( longitudinal diameter) of the heart was taken. Gestational age was assessed by fetal parameters that are biparietal diameter, femur length and abdominal circumference as per the norms in one of the Mumbai’s medical teaching institute and tertiary care centre. Results: The linear increase of the fetal heart shows a strong and significant correlation with the increase of biparietal diameter, femur length and abdominal circumference. Relationships between the cardiac data and fetal age, biparietal diameter, femur length and abdominal circumference were explored by allometry and linear regression analysis in order to estimate cardiac growth rates during third trimester. Conclusion: This study verified that the heart grows very rapidly during the third trimester (positive allometry). This suggests that noninvasive analysis of cardiac data can be useful for the assessment of gestational age or for prenatal detection of congenital heart disease [1].

Keywords: USG; BPD; FL; AC; & CL.