[Postnatal growth in very low birth weight infants: assessment with a new somatometric index].

OBJECTIVE

We have studied the postnatal growth of very low birth weight infants by using a differential index in reference to intrauterine growth evaluated by means of Lubchenko and Usher graphs.

PATIENTS AND METHODS

We analyzed the postnatal growth between birth and hospital discharge of 194 infants with birth weights less than 1500 g. No selection was made according to pathology and those newborns who died are treated as missing values. The differential index was calculated as the percentage deviation of the studied parameter and its 10th percentile and the range between the 10th and 90th percentiles.

RESULTS

The weight differential index decreased between birth and hospital discharge (20.8 +/- 33.3 versus -10.03 +/- 30.6, t = 16.97, p < 0.001), as well as that of the height differential index (30.9 +/- 39.1 versus -10.05 +/- 44.35, t = 5.65, p < 0.001), with that of cephalic growth being unchanged (23.2 +/- 43.2 versus 40.4 +/- 35.4, t = -2.29, p = NS). Newborns included in the early discharge program had a worse differential index at the final discharge than at early discharge (-19.1 +/- 27.9 versus -9.8 +/- 22.2, t = -6.1, p < 0.001). Height and cephalic growth was better at the final hospital discharge (-6.6 +/- 46.1 versus 22.7 +/- 26.1, t = -2.8, p < 0.05; 28.8 +/- 37.7 versus 50.1 +/- 27.5, t = -3.48, p < 0.01).