Siggelkow et al reported an equation for estimating the weight of a term fetus based on ultrasonographic measurements. The authors are from Johannes Gutenberg University, LMU (Munich) and University of Mainz.
Patient selection: term fetus
Mean time between the ultrasound exam and delivery was 7.2 days.
Parameters by ultrasonography:
(1) biparietal diameter in cm (BPD)
(2) thoracic diameter in cm (THD)
(3) femur length in cm (FL)
sum of the 3 parameters =
= SUM(measurement of the 3 parameters)
predicted birth weight in grams as published =
= (2.57 * (sum of the 3 parameters)) - 3,3330
predicted birth weight in grams as postulated=
= (2.57 * (sum of the 3 parameters)) + 3,3330
where:
• The units for 2.57 is g per cm.
• The paper says that the constant is -3,330, but this gives results that are suspect.
Performance:
• The mean absolute error was between 312 and 344 grams.
