Influence of additional weight in the reaching behavior of full-term and preterm infants: Analysis of categorical variables of movement

Abstract

Objective: The aim of this work is to investigate the effects of additional weight in the proximal and distal adjustments of the reaching behavior of full-term and preterm infants. Method: We evaluated 10 full-term and 9 low risk preterm infants from 5 to 7 months age. The following variables were analyzed: a) proximal adjustments: unimanual or bimanual; b) distal adjustments: hand opening (open, closed, semi-open) and hand orientation (horizontal, vertical, oblique). Variables were analyzed in two procedures: P1 (baseline) and P2 (addition of 20% of the total mass of the infant’s upper limb). To verify the association between procedures and dependent variables was applied Chi-Square Test (p<0,05). Results: Additional weight decreased of bimanual frequency for the preterm group at 5 and 7 months old, increased vertical hand frequency and decreased open hand frequency at 6 months. In the full-term group, additional weight increased the vertical hand frequency at the initiation and at the end of the movement at 5 months and at the end of the movement at 7 months. It also decreased open hand frequency at the initiation and at the end of the reaching at 6 months. Conclusion: Additional weight favored a more mature movement in the majority of variables analyzed, more expressively in the preterm group. Therefore, it can become an instrument of training this skill in the beginning of the reaching, when looking for verticalized hand unimanual reaching stimulation.