Hypoxia in Preterm Babies May Lead to Cognitive Defects

A study has found that reduced blood oxygen levels soon after birth, especially in preterm babies, are associated with lower intelligent quotients (IQs) and language skills later on. The study was published in the January 2003 issue of Neuropsychology.

The study also revealed that the risk threshold for brain damage in preterm babies could be lower than previously thought. In the study, psychologists compared the intellectual and language development of 52 children five and six years old born prematurely. Half were at slight-to-moderate risk for hypoxia. The other half had no such risk. Despite the small difference between the groups in the degree of risk, the researchers found that the two groups "diverged significantly” in their development.

This finding contradicts established thinking that regards severe oxygen deprivation as the threshold for brain damage as an all-or-nothing matter. For example, the preterm group, with mild to moderate acidosis, scored about 10-11 points lower on verbal and visuospatial tests than the low-risk preterm group.

"Most neonatologists would probably not expect to find a statistically significant relationship between degree of acidosis measured soon after birth and performance on cognitive tests in preschool and early school-age children, when acidosis is only mild to moderate at worst,” said Sarah Raz, Ph.D., a co-author from Wayne State University (Detroit, MI, USA).

Knowledge of how early risk factors affect cognitive abilities should help doctors evaluate the effectiveness of medical interventions that support preterm infants during and after birth, say the researchers.




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