<prompt> Which of the following parameter gives accurate assessment of Gestational Age?Biparietal DiameterAbdominal CircumferenceFemur LengthCrown Rump Length  <response>: Best parameters for estimation of fetal age FIRST TRIMESTER : CROWN RUMP LENGTH SECOND TRIMESTER : BIPARIETAL DIAMETER THIRD TRIMESTER : FEMUR LENGTH OVERALL : CROWN RUMP LENGTH BPD is measured in the trans thalamic view at the level of the thalami and cavum septum pellucidum. Cephalic index BPD divided by occipito frontal diameter OFD CI BPD OFD. If head shape is flattened dolichocephaly or rounded brachycephaly, then HC is more reliable than BPD. USG in Pregnancy Best time to assess gestational age by USG is 9-12 weeks by Crown rump length. Best indicator of fetal growth - Abdominal circumference. So the best USG parameter to detect IUGR is Abdominal circumference. The best USG parameter to detect Macrosomia is Abdominal circumference. 