Best marker of gestational age in 2nd trimester is :
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.
Biparietal diameter
Head circumference
Crown rump length
Femur length
General obstetrics