Reappraisal of fetal abdominal circumference in an Asian population: analysis of 50,131 records.

OBJECTIVE Fetuses from different populations may show different growth patterns. In obstetrics, fetal abdominal circumference (AC) is a very useful index for assessing fetal growth. In this study, we attempted to establish the normal fetal growth curves of AC in an Asian population in South Taiwan. MATERIALS AND METHODS We reviewed our computer ultrasound database of fetal AC records from January 1991 to December 2006. During the study period of 16 years, only the fetuses examined by ultrasonography with gestational age between 14 and 41 weeks were included. We excluded extreme bilateral records after initial analysis. Eventually, 50,131 records of AC were included for final analysis. RESULTS The observed gestation-specific AC values and the predicted AC values were calculated. The best-fit regression equation of AC versus gestational age is a second-order polynomial equation. In general, fetal AC values in our population showed similar patterns to those in Western populations. Besides, we established a table of the predicted AC values based on specific gestational age, including the 5 th , 10 th , 50 th , 90 th and 95 th centiles, for clinical reference. CONCLUSION To the best of our knowledge, our series is the largest sample of AC reported in the medical literature. We believe that the gestational age-specific nomogram of fetal AC is important for further clinical assessment of fetal growth.