Abstract
The newborn is markedly underdeveloped for the duration of human gestation. If birth weights are plotted against gestation times on double-log paper a straight line relationship is found except for a slight deviation in the case of the heaviest animals. The time required for the differentiation of man in utero is out of all proportion to all animal species. Yet the product is about one-fourth of the expected birth weight because of the adjustment to the human female. This high degree of underdevelopment makes the newborn's supervision all the more urgent to meet potential pathology with delicate desideratum.
The neonatal growth gradient continues unaltered during the postnatal period. Analysis of the growth of the body and its organs in the fetal period reveals that the course of the growth of all is essentially the same. If the prenatal growth be compared with the postnatal growth by bringing them together on an equivalent scale the characteristic form of growth of the fetal period continues for several months after birth. Therefore loss in weight is exogenous in nature.
Animal species of all sizes, of varied gestation periods, of all scales in evolution receiving no scientific supervision after birth or hatching appear to thrive either immediately or at the utmost after the second day of extrauterine life. Loss of weight in a newborn infant is therefore unnecessary when compared phylogenetically with similar processes in the entire animal kingdom.
Universality of loss of weight in the newborn without exception has glorified the phenomenon into a so-called physiologic law. A century of literature has led early investigators far afield until recent metabolic studies have indicated that the loss of weight is a result of semi-starvation and dehydration.
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