Best marker of gestational age in 2nd trimester is :: (A) Biparietal diameter, (B) Head circumference, (C) Crown rump length, (D) Femur length
Answer is A. In the second trimester the BPD most accurately reflects the gestational age, with a variant of 7-10 days. Prediction of gestational age by USG: 8-12 weeks - Crown rump length measurement Second trimester -BPD, HC Third trimester - Femur length Ref: Williams Obs 24e pg 198.