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Could birthweight prediction models be improved by adding fetal subcutaneous tissue thickness?


Dr Giovanni Larciprete, Department of Obstetrics and Gynecology, Fatebenefratelli Hospital, Isola Tiberina 39, Rome 00186, Italy. Email:


Aim:  The aims of the study were to: (i) compare the accuracy of standard ultrasonic algorithms in the estimation of fetal weight and; (ii) test two new algorithms in order to improve the global performance of birthweight prediction by adding fetal subcutaneous tissue thickness.

Methods:  We enrolled 398 patients who were between 34 and 42 weeks' gestation. Routine ultrasonographic biometric parameters as well as subcutaneous tissue thickness ultrasound parameters were measured. Correlation matrices between ultrasound parameters, in order to evaluate the degree of multicollinearity between these parameters, were assessed to develop a stepwise multiple regression birthweight predictive model.

Results:  Contributions of single ultrasound measurements in predicting birthweight were examined, by fitting Log-transformed birthweight versus single ultrasound measurements. We found that the mid-thigh tissue area was able to significantly improve the performance of the birthweight prediction process when added to the other standard ultrasound measurements. We derived two new algorithms which appeared to be better at predicting birthweight. Furthermore there was a lower minimum absolute estimation error noted when compared to other reported formulae.

Conclusions:  Our algorithms showed that the addition of the mid-thigh tissue evaluation in birthweight prediction was valuable in comparison to birthweight prediction models which are based on routine ultrasound parameters.