Committee on Fetus and Newborn

A WORKSHOP MEETING of the Committee on Fetus and Newborn and Consultants was held in Chicago on October 22, 1966, to consider standard terms for the classification of newborn infants with respect to duration of gestation, birth weight, and intra-uterine growth. INTRODUCTION Liveborn infants have usually been classified according to weight at birth because of the close association between ponderal size and the risk of death in the first hours and days of life. This simple classification has been useful in developing uniform national and international vital statistics and the data have been used to plan public health programs aimed at reducing the incidence and the high mortality of neonates who are small at birth. However, the classification based on weight alone and the international definition of prematurity (≤2,500 gm), which equated birth size and fetal age, have had the effect of obscuring medically important differences between likesize infants of dissimilar gestational ages. In view of the evidence indicating that many of the neonates included within the limits of the international definition are not born prematurely (37 weeks), the Expert Committee on Maternal and Child Health of the World Health Organization recommended that the concept of "prematurity" in the definition should give way to that of "low birth weight." Although the primary axis of classification (birth weight) remained unchanged, the new recommendation emphasized the need to use terms which make a clear distinction between size at birth and duration of gestation. In the past few years careful appraisal of newborn infants has revealed a growing number of associations between specific disorders in the neonatal period (e.g., antenatal infections, hypoglycemia, chromosomal abnormalities, respiratory distress syndrome) and either gestational age or aberrant intra-uterine growth.