Patterns of mental, motor, and language development in very low-birthweight infants

Forty-two preterm infants (10 less than 1500 grams at birth, 32 greater than 1500 grams) and 24 fullterm infants were followed between six and 24 months of age. Mental and motor development were assessed at 6, 9, 12, 15, 18, and 24 months adjusted age with the Bayley Scales of Mental Development (MDI) and the Bayley Scales of Motor Development (PDI). Comprehensive and expressive language development were assessed on the Receptive-Expressive Emergent Language Scale (REEL) at 6, 9, 12, 15, 18, 21, and 24 months adjusted age. A discriminant analysis utilizing nine perinatal factors was used to confirm the groupings of the infants. Two functions were identified which defined three groups of infants: fullterm, heavier preterm, and very low birthweight (VLBW). The first function differentiated the fullterm and preterm groups. Gestational age, the number of drugs received during the perinatal period, the rate of growth of head circumference from birth to six months and from birth to nine months, and anoxia scores were significant variables on this function. In the second function, which differentiated the heavier preterm and VLBW infants, the growth rate of head circumference between birth and six months and anoxia scores were the only significant variables. Analyses of variance revealed significant differences between the three infant groups with developmental delays in motor skills at 9, 12, and 24 months; in mental skills, at 15, 18, and 24 months; and in comprehensive language skills, at 12, 15, and 21 months. There were no significant differences between the three groups in expressive language development. None of the preterm infants caught up to fullterm performance levels during this period when preterm age equivalent scores and percentiles were compared to fullterm scores