ROLE OF FETAL THIGH CIRCUMFERENCE IN ESTIMATION OF BIRTH WEIGHT BY ULTRASOUND

Abstract

OBJECTIVE: To evaluate the accuracy and usefulness of predicting birth weight by measuring fetal thigh circumference by ultrasound. METHODS: In 110 pregnant women, fetuses without structural or chromosomal anomalies were studied prospectively and cross-sectionally. Thigh circumference (TC) was determined at the mid level of the thigh. Biparietal diameter (BPD), Head circumference (HC), Abdominal circumference (AC), and Femur length (FL) were measured using standard techniques. Fetal weights were estimated within a week prior to delivery. Statistical analysis of various ultrasound birth weight formulae in different weight categories was done and compared with each other and also with clinical methods. RESULTS: Estimated fetal birth weight using TC correlated well with actual birth weights in all categories and was superior to clinical and birth weight formulae using BPD, HC, AC and FL measurements. CONCLUSIONS: There was a good correlation between ultrasound measurement and actual postnatal measurements of thigh circumference (r2=0.89, p<0.01). Thigh circumference measurement was simple and there was better accuracy when it was combined along with BPD, HC, AC and FL measurements.