Ultrasonic fetal measurements: new Australian standards for the new millennium.

In over 30 years of ultrasound assessment of the fetus, Australian researchers have only produced growth curves for the biparietal diameter (BPD) and occipito-frontal diameter (OFD) for general use. The overseas curves used for other fetal parameters are up to 25 years old and based on predominantly white middle class sample populations. In the last decade the ethnicity in Australia has changed significantly, putting into question the accuracy of the existing charts. This 3-year study of 3,800 pregnancies has resulted in the production of fetal measurement charts for the BPD, OFD, head circumference (HC), abdominal circumference (AC), crown rump length (CRL), femur and humerus lengths. Using over 11,600 measurements collected from diverse ethnic, social and economic groups within the Australian population, rigorous statistical analysis was performed. The results showed that statistically significant differences occur between the curves currently in regular use and those for the OFD, HC, AC, CRL and humerus length obtained from our data.