Mental and motor development in preterm infants: the issue of corrected age.

This paper addresses the question of whether corrected age needs to be applied to both the mental and motor development of preterm infants during the whole of the first year. A neglected problem in this respect is that a precise developmental index cannot be found with very low or very high raw scores. Using an alternative measure of performance (age equivalent deviation score), 36 preterm infants without serious medical or neurological problems were compared with 21 full-term infants on the Dutch version of the Bayley Mental Scale at the corrected ages of 12, 18, 24, 39 and 52 weeks and the Psychomotor Scale at 24, 39 and 52 weeks. Our findings suggest that full correction should be used in assessing the mental development of relatively healthy preterm infants during the second half of the first year. Assessments at earlier ages seem to overestimate the mental abilities of preterm infants, thus indicating that partial correction should be applied at these ages. For motor development during the second half of the first year a partial correction would seem more appropriate. The clinical implications of our findings are discussed.