Postnatal growth and neuropsychological performance in preterm-birth preschoolers

Compromised postnatal growth is an important risk factor accounting for poorer neuropsychological performance of preterm children during the preschool years, yet its unique contribution to explaining outcome variance within this high risk group has yet to be determined. Therefore, we examined within a large preterm sample (1) the relationships between head growth, measured either at birth or preschool age, and outcome; (2) the relationships of binary versus dimensional head growth measures and performance; and (3) the unique contribution of preschool-age head growth, after adjustment for general physical development (indexed by stature), to variance in neuropsychological functioning.

We evaluated 264 preterm (<36 weeks) preschoolers, without severe handicaps, using cognitive, language, and motor skill measures. Multiple regression analyses, adjusting for sociodemographic factors and pre-, peri-, and postnatal confounds, were used to study associations between growth indices and performance.

While suboptimal head growth classification at birth was significantly associated only with motor performance, suboptimal head growth at preschool age explained a significant portion of variance in intellectual and language measures (g = .46 to .60). Treating preschool head size as a continuous dimension yielded null results, however, with body-height explaining a significant portion of the variance across several domains.

Among postnatal anthropometric indices, preschool stature, rather than head circumference, remains a consistent correlate of preschool outcome in preterm children, highlighting the contribution of general physical development to neuropsychological performance. Further investigation of the underlying mechanisms likely involves exploration of complex relationships between postnatal nutrition, growth hormone levels, body and brain development, and neuropsychological functioning.