Current status of fetal age and growth assessment.

Reliable fetal age assessment is now possible using antenatal sonography. Crown-rump length, biparietal diameter, head perimeter and femur length are the most widely used parameters, while biocular distance and humerus length are of ancillary value. Techniques of sonographic measurement and clinical applications are reviewed and nomograms relating these parameters to gestational age are presented. Multiple sonographic parameters have been used to diagnose altered fetal growth. Clinical applications and pitfalls in the diagnosis of IUGR are discussed when biparietal diameter, abdominal perimeter, head to abdomen ratio, total intrauterine volume, qualitative amniotic fluid determination, fetal urine production rate and estimated fetal weight are used.