A prospective study was conducted at Obafemi Awolowo University
Teaching Hospital Complex, Ile-Ife, Nigeria, between 3 January and
31May 2004, to compare the accuracy of clinical and ultrasonographic
estimation of foetal weight at term. One hundred pregnant women who
fulfilled the inclusion criteria had their foetal weight estimated in
dependently using clinical and ultrasonographic methods.Accuracy was
determined by percentage error, absolute percentage error,and
proportion of estimates within 10% of actual birth-weight (birth-weight
of +10%). Statistical analysis was done using the paired t-test, the
Wilcoxon signed-rank test, and the chi-square test. The study sample
had an actual average birthweight of 3,255+622 (range 2,150-4,950) g.
Overall, the clinical method overestimated birth-weight, while
ultrasound underestimated it. The mean absolute percentage error of the
clinical method was smaller than that of the sonographic method, and
the number of estimates within 10% of actual birthweight for the
clinical method (70%) was greater than for the sonographic method
(68%); the difference was not statistically significant. In thelow
birth-weight(<<2,500g)group, the mean errors of sonographic
estimates were significantly smaller, and significantly more
sonographic estimates (66.7%) were within 10% of actual birth-weight
than those of the clinical method (41.7%). No statistically significant
difference was observed in all the measures of accuracy for the normal
birth-weight range of 2,500-<4,000 g and in the macrosonic group
( 654,000 g), except that, while the ultrasonographic method
underestimated birth-weight, the clinical method overestimated it.
Clinical estimation of birth-weight is as accurate as
routineultrasonographic estimation, except in low-birth-weight babies.
Therefore, when the clinical method suggests weight smaller than 2,500
g, subsequent sonographic estimation is recommended to yield a better
prediction and to further evaluate foetal well-being