Can we improve the birth weight prediction? The effect of normal BMI using a multivariate model.
OBJECTIVE
The construction of a predictive model that improves the estimation of the fetal weight (EFW).


METHODS
a comparative, descriptive study. One hundred forty pregnant women were recruited at two-stage sample in health department in Spain. They were classified in four groups depending on the pre-gestational BMI. Fetal weight at term was estimated by ultrasound at 33-35 weeks (EFW40w) by one gynecologist. A regression model was created with the variables that reacted to the newborn's weight, symphysis-fundal height (SFH), EFW40w, gestational age (GA), ferritin level and cigarettes smoked.


RESULTS
A multivariate model was created for the NW group to estimate the fetal weight (EFWme), resulting in R2=0.727 (p<0.001). The differences of the averages obtained between EFW40w and EFWme, with the newborn's weight were significant (p<0.001). EFWme underestimates birth weight by 0.07 g (mean error 0.53%), and EFW40w overestimates it by 300.89 g (mean error 10.12%). In order to evaluate the predictive model and verify the predictions we used the Bland-Altman analysis. The average error in estimating the birth weight with EFWme was 1.94% underestimating the result, whereas the ultrasound error overestimated the result 10.93%.


CONCLUSIONS
The multivariate model created for the NW group improves the accuracy of the ultrasound.
PhD, Midwifery, Hospital Universitario de la Ribera, Spain. Director of Department of Nursing, Universidad Católica de Valencia.. rvila@hospital-ribera.com.
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Vila-Candel
MD, PhD, DrPH is a Full Professor at the Department of Preventive Medicine and Public Health, Universitat de Valencia, Spain. Director, Programme Management World Health Organization-EUROPE.. jose.maria.martin@uv.es.
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Martin-Moreno
PhD, Senior Nursing Lecturer, Universidad Católica de Valencia, Spain.. santiago.alamar@ucv.es.
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Alamar
Midwifery, Hospital LLuis Alcanyis, Spain. Senior Nursing Lecturer, Universidad Católica de Valencia.. francisco.soriano@ucv.es.
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Soriano-Vidal
MD, PhD, Director of Department of Obstetric and Gynaecology, Hospital Universitario de la Ribera, Spain. Associate Professor at Universidad Católica de Valencia.. fnaranjo@hospital-ribera.com.
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Naranjo de la Puerta
Nursing, MSc, Senior Nursing Lecturer, Universidad Católica de Valencia, Spain.. mt.murillo@ucv.es.
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Murillo
D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D015992:Body Mass Index; D005260:Female; D005293:Ferritins / Q000097:blood; D005333:Fetus / Q000033:anatomy & histology; D005544:Forecasting; D005865:Gestational Age; D006801:Humans; D008954:Models, Biological; D015999:Multivariate Analysis; D011247:Pregnancy; D011446:Prospective Studies; D011631:Pubic Symphysis / Q000033:anatomy & histology; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D013030:Spain; D016216:Ultrasonography, Prenatal; D014599:Uterus / Q000033:anatomy & histology; D055815:Young Adult
D005293:Ferritins