Ultrasonic Measurements of Fetal Biparietal Diameter in Normal Pregnant Northern Thai Women

Abstract

Fetal biparietal diameters (BPD) were measured by two perinatologists, who were well-trained for obstetric ultrasound, using Aloka models SSD 630 and 650. The measurements were performed on 1230 occasions in 452 women during normal pregnancies between 14 - 40 weeks (ages range 17-38 years), 205 of whom having had one examination while the remaining 247 had 1025 examinations. For each week of gestational age, the measurements were done at least on 35 occa sions. The gestational ages were based on the history of the last menstrual period, first trimester antenatal care clinic, and consistent with Dubowitz scores in every case. The mean increase in BPD between 14 - 30 weeks, 31 - 36 weeks and 37 - 40 weeks were 3.1, 1.9 and 1.3 mm/week respectively. The values of BPD for each gestational week in this study are baseline data for evaluation of fetal BPD growth in the northern part of Thailand. (Thai J Obstet Gynaecol 1990; 2: 73-79.)