Developmental outcome of very low birth weight infants as a function of biological risk and psychosocial risk.

The relative contribution of biological and psychosocial risk factors to developmental outcome of 102 very low birth weight infants (< 1500 g) was delineated through 24 months corrected age. Biological risk, assessed by the Neurobiologic Risk Score (NBRS), accounted for significant amounts of variance in Bayley Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) at the 6-, 15-, and 24-month assessment points. Psychosocial risk, reflected in maternal appraisals of daily stress, accounted for a significant increment in cognitive outcome (MDI), over and above that accounted for by the NBRS, at each assessment point. Cognitive functioning at each assessment point differed as a function of biological risk and psychosocial risk status. The findings are discussed in terms of maternal stress as a marker of, and salient intervention target for, caregiving environments that can maximize or minimize the effects of biological vulnerability.