The height-weight index of the newborn infant

Abstract

The material used in this study consisted of the records of the heights (or lengths) and weights of some 4,200 living newborn children from a number of European clinics. The lengths were all in centimeters, the weights in grams. The cases were grouped according to their lengths in centimeter intervals, the group of shortest infants including those from 47 to 48 cm. and the group of longest cases including those from 56 to 57 cm. in length. The males and females of each group were considered separately. The average weight and the standard deviation, the probable error and the coefficient of variability of the weight were determined for each group. The ponderal or height-weight index of the average weight for each group was also worked out according to the formula:

These indices were determined both on the pound-inch (avoirdupois) and the centimeter-kilogram (metric) basis. The results obtained are shown in part in the graph below and may be summarized as follows:

(1) With the increase in total body length in the latter part of prenatal life the height-weight index drops slowly, there being a decline of 1.5-2.5 per cent. (avoirdupois index) or 0.4-0.8 per cent. (metric index) between the average for 47 cm. and that for 50 cm. of total body length. In infants over 50 cm. in total body length the index declines much more rapidly, falling from an index of the average of 89.50 per cent. for males and 88.12 per cent. for females (avoirdupois) at 50 to 51 cm. to one of 79.91 per cent. for males and 80.08 per cent. for females at 56 to 57 cm. of body length. The drop in the metric index for the same period is from 25.99 per cent. to 22.94 per cent. for the males and from 25.60 per cent. to 23.24 per cent. for the females.