Downloaded From: http://archpedi.jamanetwork.com/ by a Oakland University User on 06/02/2015 the increments were corrected to express growth for 12 weeks within each interval.f The analyses reported here involved long intervals as the term children were seen only three times. The corrected increments, therefore, represented the mean 12-week growth rate during either the first year of life or during the inter¬ val between 1 and 2Y¿ years of life.Statistical Analyses.-The data on each sex were analyzed separately. In obtaining the mean and stand¬ ard deviations, the data on the prematurely born children were further divided into either birth weight groups (up to 1250 gm, 1,251-1,750 gm, and 1,751-2,100 gm) or into groups based on the presence or absence of neurological abnormalities (19% of the children were noted to have abnormalities at 2Y¡. years of age).13 No birth-weight breakdown was made for the term children. Furthermore, all the term children examined at 2Yi years were neurologically normal. Classification into three birth-weight groups and two neurological categories simultaneously was not feasible, as the number of subjects in some of the subgroups would have been too small for meaningful statistical analyses.Pearson product-moment correlations were obtained both for the measurements and for the increments t Example : The difference between the weight of a child seen at 55 weeks after birth and that of the same child seen at 133 weeks after birth was multi¬ plied by 12/(133-55). The product represented the mean rate of growth in weight per 12 weeks for the 1to 2i/2-year interval. 1 16 1,087.0 115.0 .0 -11.0 52 1,654.8 • The time in weeks from birth at which the observations were made are presented in the text.t Weight is expressed in grams through the fifth examination (1 year) and thereafter in kilograms. } CA is the chronological age or time from birth; CCA is the chronological age corrected for the number of weeks of prematurity as de¬ termined from birth weight. Since the gestational age of premature infants is less than that for full-term infants taken as 40 weeks, the cor¬ rected ages at the earlier examinations are expressed as negative numbers. § The mean birth weight of those examined at 2 y¿ years of age was 1,624 gm for the neurologically impaired males and 1,818 gm for the nor¬ mal males (i = 2.67, <0.01). | Total applies both for groups classified by birth weight and by neurological diagnosis. The mean weight of the normal boys was significantly greater than that of the impaired boys (f = 3.50, <0.01). # The mean birth weight of those examined at 2 years of age was 1,611 gm for the neurologically impaired females and 1,722 gm for the normal females (Í = 1.17).Downloaded From: http://archpedi.jamanetwork.com/ by a Oakland University User on 06/02/2015 t The mean height of the boys of higher birth weight 1,751-2,100 gm) was significantly greater than that of the boys of lower birth weight (up to 1,750 gm) (Í = 2.50, <0.05). § The mean birth weight of those examined at 2 years of age was 1,624 ...
