Relation between hand function and gross motor function in full term infants aged 4 to 8 months.

Area of Science:

• Developmental Pediatrics
• Motor Control
• Infant Development

Background:

• Reaching emerges around 4 months, followed by hand function and gross motor development (e.g., sitting).
• Despite functional links, hand and gross motor development have been studied in isolation.

Purpose of the Study:

• To examine the longitudinal changes and relationship between hand function (reaching, manipulation) and gross motor function.
• To study 13 term-born infants from 4 to 8 months, with assessments every 15 days.

Main Methods:

• Quantified reaches and manipulation time using Qualisys motion analysis from synchronized video.
• Assessed gross motor function with the Alberta Infant Motor Scale.
• Used ANOVA and hierarchical regression to analyze age effects and associations.

Main Results:

• Significant increases in reaches, manipulation time, and gross motor function were observed over time (p<0.001).
• Strong associations between reaching and gross motor function (R2=0.84; p<0.001) and manipulation and gross motor function (R2=0.13; p=0.02) were found from 4 to 6 months.
• Associations were not significant from 6 to 8 months.

Conclusions:

• The relationship between hand and gross motor function is not constant throughout development.
• The period from 4 to 6 months represents a critical window for the interdependency of hand and gross motor skill development.