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It has long been established that premature infants are at higher risk of developmental problems. These problems are linked to the fact that biological functions (such as the central nervous system and lungs) were unable to reach complete maturity during pregnancy. Incidentally, after birth, the interaction between this biological immaturity and the physical and social environment of the child plays a crucial role in his or her development.
Biological vulnerability
Generally, the lower the gestational age, the higher the impact on biological functions will be. VLBW infants (born at 32 weeks or earlier and weighing less than 1500 grams) are medically fragile and can suffer from many complications. Early studies focused on neurodevelopmental issues, such as cerebral palsy and cognitive delay. Premature infants are also at increased risk for congenital malformations, hearing and visual deficits, reactive airway disease, growth failure and behaviour problems. Among VLBW infants, about 10% will have cerebral palsy and 15% will have an IQ in the mentally deficient range.
Premature children with very low birthweights or significant medical complications show more problems with temperament in infancy and toddlerhood. These infants give their caregivers behavioural cues that are faint and much more difficult to interpret than cues given by term-born infants. They demonstrate less adaptability, rhythmicity, activity, attention and persistence than full-term infants. They also tend to be more intense in their moods, more difficult to soothe, more passive and less socially responsive. At preschool age and in the early school years, increased activity and intensity, and lack of persistence remain. This difficult temperament may lead to delayed or impaired self-regulation. However, these temperamental problems seem to be less present in children born at more than 32 weeks of gestational age.
As well, VLBW children have been found to exhibit a variety of emotional and behavioural problems, such as anxiety disorders, excessive shyness and withdrawal, social problems, poor adaptive skills and especially attention deficit hyperactivity disorder, Almost 30% will have clinically significant behaviour problems, generally related to attention deficit. In fact, these children are at more than twice the risk for developing attention deficit hyperactivity disorder, and 25% to 60% will experience difficulty in school, leading to grade repetition or requiring special education services. However, they do not appear to be at risk for developing conduct disorders.
Interaction between biological and socio-environmental factors
It is uncertain whether morbidity from neonatal complications is entirely attributable to prematurity per se. Most researchers think the consequences of prematurity are due to the interaction between the impact on neurological maturation (i.e. the brain has not had a chance to develop fully) and early parent-child problems (caused, for example, by the strain of caring for a very fragile infant or by difficulty in recognizing certain behavioural signs that are harder to identify in premature infants) that consequently affect the development of the child’s social and cognitive functions. The initial hospitalization of premature infants may result in extended separation from parents, increased anxiety and possible interference with parent-infant attachment. Moreover, children born prematurely often continue to experience physical health problems that may require frequent medical visits and re-hospitalization. This may limit their participation in regular childhood activities, which in turn may affect their development of social skills. As well, continuing parental worry that the prematurely born infant is at risk for medical and developmental problems may reflect “vulnerable child syndrome”. This syndrome may be associated with less effective parental behaviour, such as overprotectiveness, maternal separation anxiety and failure to set limits, as well as child behaviour problems, such as social withdrawal, somatic complaints, and aggressive and destructive behaviour.
The impact of adverse environmental conditions such as poverty, maternal depression and family stress on behavioural problems may be greater in premature children. On the other hand, when the mother is more responsive to the child’s cues (which are more difficult to detect in these children), VLBW children do better in terms of intellectual and social competence in early childhood.
Unfortunately, we still do not know enough to accurately anticipate the developmental trajectories of these children. More research in neurology and clinical neuropsychology would give us a better understanding of the impact of prematurity on the evolution of various neurological functions. As well, extended research on associated psycho-social factors seems equally important.
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