Risk factors associated to low birth weight

Abstract

In Chile there exists a percentage of children with low weight at birth which is very similar to the rate in developed countries. These children are in greater risk of neurologic, metabolic and cognitive capacity development deficit, also requiring special care during their development. The present paper seeks to appraise the risk factors of low weight at birth, so as to detect them in time and thus avoid their occurrence. Our study was centered on live-born babies with birth weights below 2.500 grams (n = 334), in the Maternity of the University of Chile Clinical Hospital during the years 200I and 2002. The information was obtained during prenatal attention and delivery; newborns with very low birth weight ( < 2.000 grams) were compared with those weighing 2000 grams or more. The statistical analysis considered the evaluation of the quality and consistency of the data obtained, for which purpose the Stata 8.0 program was used. It was observed that the main factor associated with very low birth weight is prematurity ( 89% ), followed by extreme age of the mother (50. 7%) and, in the third place, preeclampsia ( 44.5% ). This study concludes that the risk factors of very low weight at birth have varied in the last decade. This is explained by the change in the epidemiologic profile which the Chilean population has experienced during the last years, changing the problems of malnutrition due to deficit for those of excess and the ministerial programs that centered their efforts on the populations in nutritional risk, thus reducing malnutrition due to deficit. The low birth weight of a premature child can be explained by the gain in weight of between 200 and 300 grams as an average for each week of permanence within the uterus, specially toward the end of gestation. As respects the extreme age of the mother, it can be confirmed that adolescent girls present a greater risk of premature delivery or low weight full-term delivery due to a pre-conceptional deflcitary nutritional state (low weight gain during

pregnancy and bad controls). In women of over 35 years of age, the point is raised that the existence of chronic pathology (diabetes, hypertension, etc.) would provide the grounds for an earlier delivery. Preecclampsia is a known risk factor for low weight at birth, which produces alterations of placentation. This leads us to consider that it is possible to forestall the appearance of these factors and thus diminish the number of infants with very low birth weights.