Fetal Biparietal Diameters in Normal Pregnant Southern Thai Women

Abstract

The Thai population has different anthropometric parameters from the Western standard. In order to utilize ultrasonographic data on fetal biparietal diameter (BPD) for prediction of fetal gestational age (GA) and growth monitoring, it is necessary to establish local standards. The objective of this study was to create our own normogram by ultrasonography and growth rate of the fetus at different gestational ages. 

A total of 901 normal pregnant women, residing in the Southern provinces of Thailand, between 12 to 40 weeks of pregnancy were measured for BPD by real time ultrasonography. All of the subjects delivered normal fetuses. BPD curve versus gestational age showed two straight lines that joined at BPD 70 mm. Corres pondingly, the growth rate of BPD is higher when GA or BPD is small and be comes lowest near term with a relatively rapid decline at the 28th week or BPD = 70 mm. 

It is concluded that BPD can be easily measured by ultrasonography and helps in predicting the gestational age and growth rate of the fetus. (Thai J Obstet Gynaecol 1991;3:71-77.)