An impact of birth weight on postnatal body and organ growth capacity in infants under one year of age.

The aim of this study was to evaluate the possible impact of birth weight and other major neonatal infant characteristics on body and organ growth capacity throughout the first year of life. The study group consisted of 138 infants under one year of age, who died in St. Petersburg between 1983 and 1992 of confirmed acute respiratory infections without congenital anomalies, intrauterine infections, signs of metabolic and progressive diseases according to clinical and morphological data. By means of linear regression analysis it was revealed that birth weight was the most important influential factor among other neonatal characteristics as far as infant growth in postnatal period was concerned. For body weight, head and chest circumferences, the influence of low birth weight seemed to diminish with advancing age, whereas for the body length this effect was more persistent. Gestational age, length, and ponderal index at birth were not critical determinants as far as infant postnatal growth capacity was concerned. Organ weights in postnatal life were also dependent on infant birth weight. Brain and heart appeared to be able to recuperate from initial weight deficit within the first year of life and thus seemed to be relatively spare of the fetal growth retardation, while for the liver and kidneys, this restricting influence was more prominent.