Introduction <p>Accurate assessment of the gestation age (GA) is essential in management of all pregnancies. Ultrasound has been a very reliable tool for estimating GA in early pregnancy using fetal crown rump length (CRL).As pregnancy progresses, parameters such as biparietal diameter (BPD), head circumference (HC), femur length (FL) and abdominal circumference (AC) are used for estimation of fetal GA. However, these parameters are of limited use in late pregnancy with disparity of up to two to three weeks in assessment of GA in third trimester. Hence, this study was performed to determine whether novel fetal biometry measurements such as fetal colon diameter (FCD), fetal kidney length (FKL), transcerebellar diameter (TCD) and fetal pinna length (FPL) can be used as independent parameters for estimating GA in third trimester.</p> Methodology <p>This was a hospital-based prospective cross-sectional study conducted in the Department of Obstetrics and Gynecology along with the Department of Radiology, AIIMS, Mangalagiri, over a period of 2&#xa0;years from November 2020 to November 2022 after obtaining Institute Ethical clearance. Pregnant women at 28 to 40&#xa0;weeks of gestation for whom ultrasound was advised for assessment of fetal growth and well-being, and who fulfilled the inclusion criteria were recruited for the study. The GA of fetus was assessed by standard parameters (BPD, HC, AC and FL). In addition, the novel fetal parameters (FCD, FKL, TCD, FPL) were measured. Correlation of ultrasonographic measurement of novel fetal parameters with GA was assessed. In addition, correlation of novel fetal biometry measurements with that of standard fetal parameters (BPD, HC, AC and FL) was also assessed.</p> Results <p>A total of 121 study participants were included in the study. The mean (SD) maternal age was 25 (1.0) years, and the mean (SD) gestational age was 33.1 ± 2.6&#xa0;weeks. Majority of the participants were primigravida (58%) The mean and SD of all the routine and novel fetal biometric parameters showed gradual increase with GA. The GA had very strong positive correlation with novel fetal parameters FCD (<i>r</i> = 0.94), FKL (<i>r</i> = 0.91) and TCD (<i>r</i> = 0.97) and a strong positive correlation with FPL (<i>r</i> = 0.88). All the novel fetal parameters showed either very strong or strong correlation with routine fetal biometric parameters. Regression model for individual novel fetal parameter (FCD, TCD, FKL, FPL) to predict GA revealed a significant linear relationship with GA. The highest predictability (R²) was found with TCD (0.95) followed by FCD (0.89). The overall model predictability (R²) for all novel fetal parameters was 0.970 which was almost equal to the model predictability of routine fetal parameters (0.973).</p> Conclusion <p>Our study was the first of its kind done to determine the role of four novel fetal parameters in assessment of GA in the same setting. Linear relation was observed between GA and all the novel fetal parameters (FCD, FKL, FPL, TCD). The correlation coefficient was statistically significant, and regression analysis shows a strong significant relationship for GA prediction using all the novel fetal parameters. Our study concluded that measurement of FCD, FKL, FPL, TCD along with other routine parameters can give a better prediction of GA in late trimester.</p>