Cover Image
close this bookActivity, Energy Expenditure and Energy Requirements of Infants and Children (International Dietary Energy Consultative Group - IDECG, 1989, 412 pages)
close this folderLong-term developmental implications of motor maturation and physical activity in infancy in a nutritionally at risk population
View the document(introductory text...)
View the documentAbstract
View the document1. Background
View the document2. A theoretical formulation
View the document3. Purpose
Open this folder and view contents4. Methods
View the document5. Results
View the document6. Discussion
View the documentReferences
View the documentDiscussion (summarized by C.M. Super)

5. Results

Table 1 presents the results from the first two sets of analyses: (1) correlations between birth weight and the developmental test scores at 15 months of age; (2) correlations between the physical growth measurements at 15 months and the developmental test scores at 15 months. Correlations which include height and weight measures at 15 months, partialling out the covariance with birth weight, are also included. The table also presents correlations between anthropometric data and motor scores, partialling out the variance shared with the mental scale scores. The correlation between the mental and motor scales was 0.426 (N = 365; p < .000l).

Table 1. Correlations: Prenatal (birth weight) and postnatal growth measurements with development test scores (mental and motor) at 15 months

Measurement

Motor

Mental

Motor (mental partialled out)

Birth weight (BW) (N = 274)

.067

.113

.021

Z-Weight-for-age 15 mo (N = 325)

.314 **

.188 *

.317 **

Z-Weight (BW partialled out)

.307 **

.142 *

.272 "

Z-Height-for-age

.357 **

.177 **

.362 **

Z-Height (BW partialled out)

.352 **

.139*

.323 **

Z-Weight-for-height

.047

.079

.084

Z-Weight-for-height (BW partialled out)

.023

.036

.008

* p < .05
* p < .001

The correlations between birthweight and the mental and motor test scores were not statistically significant. Likewise, the correlations between weight-for-height at 15 months and the mental and motor scores were not significantly different from zero. Conversely, the correlations between weight-for-age and height-forage (with or without the shared variance with birthweight) and the mental and motor scores were statistically significant. However, the magnitude of the correlations differ between those involving the mental and motor scores. Among the correlations involving the mental test scores the highest coefficient was 0.188 with weight-forage; on the other hand, the lowest coefficient including the motor score was 0.307, with weight (partialling out birthweight effects). These two coefficients were significantly different (p < .05) from each other. Height-for-age at 15 months, the anthropometric indicator most highly correlated with motor development, explained about 13% of the motor scale variance.

Figure 3 presents the set of correlations between the measurements at 15 months of age and the verbal factor from the Preschool Battery at 36, 48, 60, 72 and 84 months of age.


Figure 3. Correlation coefficients: Developmental test scores and anthropometry with verbal factor scores at five ages (36 to 84 months).

Measurements at 15 months include height-for-age, weight-forage, and the mental and motor scale scores. The motor score at 15 months was a better predictor of verbal scores at 36 and at 48 months of age than the mental score at 15 months. However, those differences in predictive power between the mental and motor scores disappeared at 60, 72 and 84 months. Height-for-age and weight-for-age at 15 months were equally good if not better predictors of performance from 36 to 84 months than the motor scores at 15 months.

In connection with the assumptions of this paper regarding the importance of early motor maturation for later development in a population which is nutritionally at risk, the final set of analyses are of critical importance. These analyses specifically focus on the predictive power of early motor maturation on adolescent functional performance. As already indicated, it is well established that in well-nourished populations the correlations between early motor maturation and adolescent functional performance are not significantly different from zero.

Figures 4-8 are histograms reporting the magnitude of the correlations between the mental and motor scores and anthropometry at 15 months, and scores on tests of functional performance in adolescence. In all except one case (i.e., Raven Progressive Matrices), the motor test scores at 15 months predicted the scores on the outcome variable in adolescence. In particular, after controlling for mental test scores, the motor test scores predicted literacy (r = .16; p < .05; N = 220), reading scores (r = .22, p < .01; N = 173), vocabulary scores (r = .18; p < .05; N = 173), and the maximum grade attained in school (r = 14; p < .05; N = 231) in adolescence. Conversely, the mental test scores, weight-for-age and height-for-age at 15 months failed to predict any of the outcome variables in adolescence.


Figure 4. Correlation coefficients: Mental, motor, and body growth measurements at 15 months and reading score (Interamericana) in adolescence.


Figure 5. Correlation coefficients: Mental, motor, and body growth measurements at 15 months and literacy score in adolescence.


Figure 6. Correlation coefficients: Mental, motor, and body growth measurements at 15 months and score in Raven Progressive Matrices in adolescence.


Figure 7. Correlation coefficients: Mental, motor, and body growth measurements at 15 months and maximum school grade attained.


Figure 8. Correlation coefficients: Mental, motor, and body growth measurements at 15 months and vocabulary score (Interamericana) in adolescence.