On the weight increments of premature infants as compared with those of fetuses of the same gestation age and those of full-term children

One method of approaching the problem of the effect of birth and the postnatal environment on the course of human growth is by the comparison of the rates of growth of premature infants with the growth rates of fetuses of the same gestation age and with those of full-term children. If the environmental factors are the all-important ones it might be expected a priori that the rate of growth of prematures would agree, in the main, with that of full-term children. If, on the other hand, the effects of the extrauterine environment do not seriously modify the course of growth established in prenatal life, it is to be expected that the curve of rate of growth in prematures will follow in general that of the fetus of the same gestation age.

The following study was based upon the weight records of 78 premature infants. In collecting the histories all cases were included which made any gain in weight in the first month after birth. These cases were divided in four groups according to their birth weight, and the rate of growth in the form of the monthly percentage increment in weight was determined separately for each case. The mean monthly increment of each groud for each month was then determined by averaging these individual percentages. The results obtained are shown in the table below. It will be noted : first, that the percentage increment in weight of prematures in the first postnatal month is lower than in the second month, and that following the second month the rate of increment gradually decreases; and, second, the percentage increments are in a general way inversely proportional to the birth weight.

The increments thus determined were next compared with those of fetuses of the same gestation age and with those of fullterm newborn children.