Assessment of gestational age of the Asian fetus by the sonar measurement of crown-rump length and biparietal diameter.

Two populations of pregnant Asian and European women were scanned using linear array real-time ultrasound machines. Measurements were made of fetal crown-rump length (CRL) up to 14 weeks gestational age and of biparietal diameter (BPD) up to 20 weeks gestational age. Polynomial growth curves relating CRL and BPD measurements to their gestational ages were fitted to the data by the method of unweighted least squares. There were no significant differences between the Asian and European parameters for the CRL and BPD curves. European nomograms may be used to establish Asian fetal gestational age up to 20 weeks.