Infant growth after preterm birth and neurocognitive abilities in young adulthood.

Objectives: To examine whether faster growth from birth to term (40 postmenstrual weeks) and during the first year thereafter was associated with better neurocognitive abilities in adults born preterm with very low birth weight (VLBW; <1500 g).

Study Design: Weight, length, and head circumference data of 103 VLBW participants of the Helsinki Study of Very Low Birth Weight Adults were collected from records. Measures at term and at 12 months of corrected age were interpolated. The participants underwent tests of general neurocognitive ability, executive functioning, attention, and visual memory at mean age of 25.0 years.

Results: Faster growth from birth to term was associated with better general neurocognitive abilities, executive functioning, and visual memory in young adulthood. Effect sizes in SD units ranged from 0.23-0.43 per each SD faster growth in weight, length, or head circumference (95% CI 0.003-0.64; P values <.05). After controlling for neonatal complications, faster growth in head circumference remained more clearly associated with neurocognitive abilities than weight or length did. Growth during the first year after term was not consistently associated with neurocognitive abilities.

Conclusions: Within a VLBW group with high variability in early growth, faster growth from birth to term is associated with better neurocognitive abilities in young adulthood. Neurocognitive outcomes were predicted, in particular, by early postnatal head growth.