Growth and proportionality in early childhood. I. Within population variations.

Data on the postnatal growth patterns of 238 small-for-gestational age (SGA) and 241 large-for-gestational age (LGA) babies are presented. Three proportionality ratios were selected; and their changes in shape, by these indices, during the first 7 years are compared with a random sample of 284 children drawn from the same population. Highly significant differences (P less than 0.001) were found between the mean head-chest and head-length ratios for both sexes at birth; but mean chest-length ratios did not differ. Our findings show that these three measures of proportionality differ in their patterns of change over time; in the influence of birthweight group on their absolute values at each age; and the influence of sex within birthweight groups. At 7 years SGA children still had the highest and LGA children the lowest head-chest and head-stature ratios, and the differences were significant (P less than 0.01) for girls. This was mainly due to the relatively small heads of LGA girls. 46% of our sample had a head-chest ratio above unity at the age of 2 years. The "rule of thumb" criterion for the identification of malnourished children, based on the general principle that mean chest circumference overtakes head circumference by the age of 12 months, should not be too strictly applied.