<prompt> True statement regarding this fetal parameter is?Best parameter for dating pregnancyCan be measured till 10 weeks onlyAccuracy for gestational age estimation is - 7 to 10 daysFetus is measured from head to toe  <response>: Ans. A. Best parameter for dating pregnancyCRL - Crown Rump lengtha. 1st trimester CRL is the best parameter for dating pregnancy. If carefully performed it has a variance of 3 - 5 days.b. Ideal time to perform CRL is between 7 to 10 weeks but can be done up till 14 weeks till the embryo is 85mm longc. The fetus is measured in the mid-sagittal plane from crown to the rump. 