A longitudinal study of the physical growth of Japanese infants

In order to clarify the characteristics of the physical growth of Japanese infants up to 1 year of age, the data of 3183 infants from 53 hospitals in Japan were collected. Percentile values were calculated from the measurement of body weight, recumbent length, and head circumference, with some additional data interpolated to fill the gaps in the measurements. Compared to the National Center for Health Statistics (NCHS) standard, the recumbent length and head circumference of these infants were smaller throughout the observation period, while body weight was larger at 0-6 months of age, and smaller at 8-12 months of age. The cases were divided into five groups according to birth weight, to examine the influence of foetal growth. The 50th percentile curves of each group were parallel and the intervals between the 3rd and 97th percentile curves in each group became wider in the first 6 months of life, up to the interval of 2.20-3.18 Kg. There was no significant difference in body weight among three groups according to feeding methods, in any age period.