The estimation of fetal birth weight is an important factor in the management of high risk pregnancies. The information and knowledge gained through this study, comparing a combination of various fetal parameters using computer assisted analysis, will help the obstetrician to screen the high risk pregnancies, monitor the growth and development, and determine the gestational age and weight of fetuses more accurately. A prospective ultrasonic study of 120 booked pregnant patients, with singleton pregnancies, at term, without any chronic illness was done 1 - 20 days prior to delivery. Measurements of their head and abdominal circumference (HC and AC), biparietal diameter (BPD) and femur length (FL) were obtained to calculate the fetal birth weight. Computerized statistical evaluation was done using various internationally recognized models and results were compared with actual birth weight at delivery. The gestational age at delivery was between 37 - 42 weeks. The age range of patients was between 16 - 41 years, with a mean of 30.7 years. The actual range of birth weights was 2500 - 4700 g, with a mean of 3390 g (SD 381). This study showed that regression models incorporating HC and AC were not as good as those using AC and BPD. The use of femur length and abdominal circumference, AC/FL, did not improve accuracy. The use of multiple parameters, gives the most accurate prediction of fetal weight.

 

Key words: Sonography, birth weight, head, abdominal circumference, biparietal diameter, femur length.