In order to evaluate eventual advantages a modified cow milk (Alprem^, a controlled prospective trial was done comparing two groups of newborn babies whose birthweights ranged between 1.200 and 1.700 g. Fifteen babies.in the study group were fed with Alprem and 12 babies in the control group were fed with a different formula (Nan©). Clinical, biochemical and anthiopometric parameters were determined serially in both groups. Tolerance to feedings, serum calcium, phosphorus, alcaline phosphatase and proteins showed no differences between both groups. There was no difference either in urinary density nor in the incidence of haemotytic signs. Weight gain was slightly higher in the study group (33.04 ± 4.85 g/day vs 27.4 ± 5.28 g/day) but this difference was not significant. Babies who received Alprem had significantly lower incidence of late metabolic acidosis: 9.1% vs. 45.1 % in the control group (p < 0.001), nevertheless acidotic babies in both groups had normal weight gains and their acidosis normalized without any treatment nor change in their formula. Alprem appears to be a good alternative to feed low birthweight babies when there in no chance to give breastmilk. (Key words: Cow milk, modified, low birthweight, neonates, newborn infants).Los recien nacidos de bajo peso, tanto los que nacen con un peso adecuado como aquellos que tienen un peso bajo para su edad gestacional, determinan un desafio nutricional cuyo ultimo objetivo es lograr un desarrollo normal en el corto y en el largo plazo. La leche materna aparece como el alimento ideal, por lo cuai se ban desarrollado variados sistemas para su recoleccion tanto en bancos de leche como en lactarios, aun cuando se discute si cumple con todas las exigencias nutricionales y mincrales para el recien nacido de bajo peso (RNBP) 1 -2 -3 . La leche materna debe ser sustituida en numerosos casos y entre las alternativas nutricionales se ha ensayado las mas diversas tecnicas y formulas para" lograr cubrir los requerimientos nutritives. Se pretende emplear una formula homogenea en su composicion quimica, que permita una buena tolerancia digestiva, evite la esteatorrea secundaria y logre en los RNBP una curva pondoestatural semej ante al ritmo de crecimiento intrauterino.4,5,6.7

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