Objective: The purpose of this work was to examine the relations among neuromaturation, mother-infant relationship, and cognitive development in small-for-gestational-age premature infants and to assess the interactive effects of birth weight and intrauterine growth restriction on developmental outcomes.
Methods: We studied 120 singleton premature infants (birth weight: 530-1790 g; gestational age: 25-35 weeks). In group 1, 40 small-for-gestational-age infants (22 girls) were case-matched with group 2 (n = 40) for birth weight (appropriate for gestational age matched for birth weight) and group 3 (n = 40) matched for gestational age (appropriate for gestational age matched for gestational age). Exclusion criteria included intraventricular hemorrhage grade 4, perinatal asphyxia, central nervous system infections, and genetic conditions. Infants were further divided into those born below and above 1000-g subgroups. Neonatal state organization was observed for 4 consecutive hours. Neuromaturation was assessed with the Neonatal Behavioral Assessment Scale. At 3 and 24 months' corrected age, mother-infant interaction was evaluated. At 1 and 2 years' corrected age, the infants' cognitive development was tested with the Bayley Scale of Infant Development, 2nd edition.
Results: Small-for-gestational-age infants showed less organized state and less mature neurobehavioral profiles, particularly in the orientation and motor domains. Mother-infant interactions were characterized by maternal intrusiveness and miscoordination and negative infant engagement. Cognitive outcomes at 1 and 2 years were lower for the small-for-gestational-age group. Small-for-gestational-age infants born < 1000 g showed the poorest neurodevelopmental, social, and cognitive development of all of the groups. Cognitive outcomes at 2 years were predicted by small-for-gestational-age status, the interaction of actual birth weight and small-for-gestational-age status, neonatal state organization, and maternal intrusive behavior.
Conclusion: Small-for-gestational-age premature infants are at higher risk for developmental and cognitive delays, as well as difficulties in the mother-infant relationship across infancy. Those born at extremely low birth weight are at a double risk. This group should receive special clinical attention and care.