When performed with quality and precision, ultrasound alone is more accurate than a “certain” menstrual date for determining gestational age in the first and second trimesters (≤23 weeks) in spontaneous conceptions, and it is the best method for estimating the delivery date  .The aim of this research was exploring the accuracy of ultrasonic measurement of biparietal diameter (BPD) and femur length (FL) in assessing gestational age in the third trimester of pregnancy.2.Women who participated in the study were selected on following criteria: Regular menstrual cycles, known date of last menstrual period and previous live normal neonates in multipara.
Only women with single live fetus were included in this study.
All patients were examined for any other complication.
Gravid females with single live fetus with no complication i.e., congenital anomaly, or growth restriction were included.
Material and Methods The study was conducted in 53 pregnant women who came for ultrasonography in the Maternity & Children’s Hospital in Jeddah.
Only women with 20 - 36 weeks CUA (composite ultrasonographic age) till term were included in this study.