[Multicenter study of fetal weight estimation in term pregnancies].
OBJECTIVE
The aim of this study was to evaluate the utility of the Johnson and Toshach technique to predict the fetal weight in patients who went on to deliver after full term pregnancies in four hospitals of second level.


METHODS
At the hospitals participating in the study for one year, 504 pregnant patients, with or without signs of labor in pelvic or cephalic presentation were randomly selected from among the total number of pregnant patients admitted. An obstetric history and examination were performed and a questionnaire designed specially for the trial was filled out. The body mass index (BMI kg/m2) was calculated in order to allocate the patient into three groups (< 25, 25-29.9, > 30), the hemoglobin values were determinate and the patients were then allocated into further group Hb > 10.5 y Hb < or = 10.5 The measurement of the fundus was determinate for the initial observer and after that corroborated by a second observer in a blind test. Then the calculation of the fetal weight was carried out using the Johnson and Toshach formula which was compared with the immediate neonatal weight. The Student's t test and the Mann-Whitney test were used when necessary for the comparison of means. The statistical analysis was carried out with SPSS V 10.0 program.


RESULTS
The estimated global weight calculation in the new born using the Johnson and Toshach technique which was determinate from the average of both observers (1 and 2) and its correlation with the immediate neonatal weight were 3,115.4 g vs 3,055.6 g, with a p-value without significant differences and t-value was 0.0094; the global standard deviation +/- 450.7 g vs 448.7 g with p-value without significant differences and a confidence intervals of 95%.


CONCLUSIONS
Predicting the clinical fetal weight using the Johnson and Toshach technique is an accurate, non-invasive, and essentially easy way of determining fetal weight that yields results with minimal variation between observers and holds a very high predictive value. This technique allows us to accurately predict the fetal weight in term pregnancies with or without labor.
Sauceda González
Luciano Francisco
LF
Hospital General de Zona 2 A Troncoso, IMSS, D.F.
Ramírez Sordo
Jorge
J
Rivera Flores
Salvador
S
Falcón Martínez
Juan Carlos
JC
Zarain Llaguno
Fernando
F
D000328:Adult; D001724:Birth Weight; D015992:Body Mass Index; D005260:Female; D020567:Fetal Weight / Q000502:physiology*; D006801:Humans; D015337:Multicenter Studies as Topic; D011237:Predictive Value of Tests; D011247:Pregnancy; D012016:Reference Values