Infants with low rate of weight gain. I. A study of organic factors and growth patterns.

To evaluate the clinical significance of low rate of weight gain 81 infants wer investigated with a deviation of weight corresponding to a decrease of at least one S.D.-score of weight attained in the current Swedish growth chart. In 28 patients this decrease was of organic origin, notably intestinal disease. Three different growth variables were compared: attained weight (transformed to S.D.-score), change in S.D.-score of attained weight per time unit (= rate of change of deviation in S.D.-score/year) and rate of weight gain in kg/year (transformed to S.D.-score). Twenty-two of 28 infants with organic diseases had a subnormal rate of weight gain whereas only 12 attained subnormal weight for age. The use of rate of weight gain is the most sensitive growth variable and is far better than the use of attained weight as an indicator of ill-health. Change in S.D.-score of attained weight for screening purposes give good agreement with rate of weight gain, provided that age is taken into account.