Optimizing Neuromotor Outcomes Among Very Preterm, Very Low-Birth-Weight Infants

In the 1980s, the outcomes of infants who were born with very low (<1500 g) or extremely low (<1000 g) birth weight were reported in terms of major neurodevelopmental consequences on motor and sensory functioning. These high-severity, relatively low-frequency disorders include the cerebral palsy syndromes of diplegia, hemiplegia, and quadriplegia, as well as neurosensory disability from retinopathy of prematurity and sensorineural hearing loss. With advances in maternal fetal medicine, high-risk obstetrics, neonatology, and ophthalmology, the combined rates of these disorders are less than 10% in those born very low birth weight, between 15% and 20% in those born extremely low birth weight, and less than 0.5% in term-born infants.^{1 - 2}

However, there is increasing recognition that absence of these major neurodevelopmental disabilities in early childhood does not guarantee that more subtle aspects of neuromotor functioning will develop smoothly and with easily mastered developmental trajectories over time.³ These so-called minor neuromotor disorders affect gross motor coordination, balance, and motor planning, as well as fine motor skills that underlie manipulation, self-care skills, and handwriting, and require both higher cortical and subcortical gray and white matter connectivity.^{4 - 5} The long-term consequences of these disorders are far from a simple maturational lag. In this context, assessment of motor skills using valid instruments can be viewed as an important early indicator of central nervous system developmental processes.

For these reasons, the meta-analysis by de Kieviet and colleagues⁶ in this issue of JAMA is so important, involving studies including 9653 children without major disability who were very or extremely low birth weight or very (28-31 weeks) or extremely (<28 weeks) premature. In systematically evaluating the motor assessments of 6848 infants and toddlers, the authors report an effect size of −0.88 z, which translates to a standard score of 13 points lower compared with typically developing term-born peers on the Bayley Scales of Infant Development II. This effect size represents more than a tripling of the expected rate of children performing at less than the 10th percentile in gross and fine motor skills. These delays increase the number of children who need to receive motor and developmental interventions in the early intervention system currently overwhelmed with addressing the complex challenges faced by many young families.

Moreover, as de Kieviet et al⁶ show, in the preschool years and in middle childhood these delays persisted, as demonstrated by the Bruininks-Oseretsky Test of Motor Proficiency, a multidimensional battery that assesses coordination, balance, running, manipulation, fine motor control, and motor planning. These impairments significantly challenge children who attend preschool and early elementary school with respect to running, jumping, drawing, copying, constructing, and spelling and also may make it difficult for these children to keep up with both academic and social activities.^{7 - 9} In addition, in later childhood, ongoing impairments continue rather than being outgrown and are highly correlated with nonverbal learning skills, math and handwriting performance, and participation in recreation and extracurricular activities.¹⁰

In interpreting these results, health professionals must realize that motor skills can be improved by intervention and practice. Developmental sports activities, playground and outdoor exercises, playing with blocks and puzzles, manipulating small toys, pretend play, drawing, coloring, and playing the piano all improve with experience. An increased risk of developmental coordination disorders in these children means that health professionals and families must be aware of the common comorbidities in attention, executive function, and perception that may be present. Appropriate accommodations and interventions can be implemented to reduce the difficulties these children have in keeping pace with school work and engaging peers in activities outside of school. A robust literature exists about interventions for perceptual motor delays in children with established developmental disorders. Even among children with cognitive impairment (IQ <70), motor performance can be enhanced by explicit teaching and intervention strategies.¹¹

Most importantly, health professionals must realize that the most common sequelae of prematurity involve reading disorders and neuropsychological disorders affecting executive function and memory.^{12 - 13} Explicit supports in the school environment can lessen the spiral of missed opportunities that result in the educational crises of grade repetition, social promotion, and special education services that do not promote the skills required in today's society.^{14 - 15}

The findings of the meta-analysis by de Kieviet et al⁶ highlight the potential for long-term adverse developmental trajectories. Opportunities for neuroprotection occur not only at a biomedical level but also at developmental and societal levels. By supporting these children and families through preschool and educational interventions, these motor indicators of central nervous system vulnerability do not inevitably need to follow a cumulative trajectory that interferes with educational, social, and community success.