Postnatal growth curves of very low birthweight Japanese infants.

To construct standard growth curves for Japanese infants of very low birthweight, longitudinal data provided by 47 neonatal centers in Japan were reviewed. Data were collected on the growth of infants admitted to those units during 1986 and 1987 and who survived beyond 3 years of age. A total of 379 singleton infants, who were free of neurological sequelae and appropriate for gestational age, were enrolled. Those whose birthweights were more than 600 g and less than 1,500 g were grouped into nine weight categories separated by increments of 100 g. Data on the increase in weight and head circumference were compiled and analyzed until more than half the infants in each weight category had been discharged from each site. Growth curves of bodyweight and head circumference in the nine groups were constructed using polynomial regression analysis to define the curve of best fit. With increasing prematurity, significant trends of greater weight loss (P < 0.05), longer time to reach the lowest weight (P < 0.01) and a longer time to regain birthweight (P < 0.01) were observed. In addition, there was a significantly higher incidence of chronic lung disease in such groups (P < 0.0001). Growth curves were characterized by the average clinical profiles in each of the nine groups. We believe that these data will be useful in evaluating the growth of very low birthweight infants being cared for in modern neonatal intensive care units in Japan.