Comparison of ultrasound fetal biometry of singleton fetuses with a reference chart in pregnant women with normal nutritional and health status

Objetives The aim of this study was to compare fetal biometry of singleton fetuses in pregnant women with normal nutritional and health status in the Ampara district, with a commonly used reference chart. Methods A cross sectional study was carried out in the Ampara District. Women with normal nutritional and health status and minimal environmental constraints on fetal growth (n=714) were enrolled during the first trimester and gestational age was confirmed by fetal crown-rump length measurement between 11 weeks + 0 days and 13 weeks + 6 days. For this study, each mother was considered only once for measurement of fetal biometry, at gestations between 11 and 41 weeks. Fetal bi-parietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL) were measured using standard techniques, and separate regression models were fitted to estimate the means and standard deviations and derive gestation specific centiles for each parameter, assuming that the measurements have a normal distribution at each gestational age. The fetal biometry results obtained from the current study were compared with a commonly used reference chart. Results The fitted 10th, 50th and 90th centiles at 40 weeks of gestation were, 87.9 mm, 93.2 mm and 98.5 mm for BPD, 313.8 mm, 328.9 mm and 344.0 mm for HC; 298.2 mm, 322.5 mm and 346.9 mm for AC and 69.7 mm, 75.0 mm and 80.2 mm for FL. When compared with the reference chart, significant differences of fetal biometry were seen in the third trimester but not in the second trimester. Conclusions Ultrasound fetal biometry of singleton fetuses in pregnant women with normal nutritional and health status in the Ampara District were significantly different in the third trimester, from a routinely used reference chart.