Impact of gestational age on preterm motor development at 4 months chronological and adjusted ages.

ABSTRACT

A cohort of 62 low-risk preterm infants was identified and followed prospectively through the first 4 months of life to assess whether motor development is determined by biological maturity or the duration of the extrauterine experience. After identification, the cohort was subdivided into two groups according to gestational age at birth less than 32 weeks gestation (n = 23) and greater than or equal to 32 weeks gestation (n = 39). Neuromotor assessments were performed on every infant at both 4 months chronological and 4 months adjusted ages. Analyses revealed that (1) the two groups of infants differed significantly at 4 months chronological age in terms of tone, primitive reflexes and volitional movement, but not in automatic reactions, and (2) the two groups of infants differed significantly at 4 months adjusted age in terms of primitive reflexes, but not in tone, automatic reactions or volitional movement. These findings suggest that the development of volitional movement and tone appear to evolve according to biological maturity alone. In contrast, primitive reflexes and automatic reactions in the preterm infant may be influenced by both biological maturation and environmental experience.