Validation Study of Hadlock3 Model of Foetal Weight Estimation

Abstract

Aim: The aim of this study was to evaluate the validity of Hadlock 3 model of foetal weight
estimation among fetuses in a Nigerian population.
Methods: 2008 mothers with singleton term pregnancy admitted in the labour ward of Ebonyi
State University Teaching Hospital for planned delivery were recruited for the study. Subjects
who met the inclusion criteria were scanned within 24 hours prior to delivery. A greyscale
high resolution ultrasound machine, Sonoace 5500, manufactured by Medicol in Korea, with a
3.5 MHz transducer was used to obtain the sonographic measurements. The birth weights of
the fetuses were estimated using Hadlock3 model for foetal weight estimation. The actual
weights of the neonates were measured immediately after birth by an experienced midwife.
Intra-class correlation coefficient was used to compare the ultrasound estimated fetal weight
with the actual fetal birth weight.
Results: The mean actual birth weight of the neonates was 3.42 ± 0.36 kg while the mean
estimate obtained from Hadlock3 model was 3.44 ± 0.45kg. There was no statistically
significant difference between the estimated mean weight and the actual weight of the
neonates at the reference birth weight (P < 0.05). The accuracy of this model was highest at
the weight range of 3.00 to 3.99 kg, with inter-class co-efficient of 0.88 and accuracy of 86 %
within ± 10 % of actual birth weight.
Conclusion: Hadlock3 model has a high intra-class correlation coefficient of 0.88 at birth
weight of 3.00 to 3.49 kg and predicts the birth weight in 86% of cases within ± 10% of
actual birth weight.