Ultrasound measurement of fetal abdominal circumference and the ratio of biparietal diameter to transverse abdominal diameter in a mixed Nigerian population.

The fetal abdominal circumference (FAC) and biparietal diameter to transverse abdominal diameter ratio (BPD/TAD) were measured by ultrasound in 219 normal pregnant Nigerian women from 20 weeks until term using the cross-sectional method. There was a progressive linear growth of the FAC and a consistent standard deviation throughout the study period. When compared to caucasian growth curves, the curve shapes were identical but the FAC values were consistently less for each week of gestation in our Nigerian sample. The BPD/TAD ratio showed a progressive fall from 20 weeks until term similar to that previously noted for fetal head circumference to abdominal circumference ratio, indicating that this parameter may also be useful for predicting abnormal fetal growth.