A new publication examines in great detail the cognitive outcomes of preterm babies less than 29 weeks gestation. The group from Melbourne, the Victorian Infant Collaborative, has published another study. (Hutchinson EA, De Luca CR, Doyle LW, et al: School-age Outcomes of Extremely Preterm or Extremely Low Birth Weight Children. Pediatrics 2013) I don’t know where Lex Doyle gets the time to do everything that he does, but this study is another from an incredibly productive group that examines the outcomes at about 8 years of age for a population cohort of babies (n=189, 94% of the babies were followed up) that were less than 28 weeks or less than 1000g birth weight, and were born in 1997.
The results are extremely encouraging; the full scale IQ of the extremely preterm infants is about 0.8 SD below the term controls, actual academic achievement is about 0.5 SD worse than the term controls, and there are 15% of the babies classified as having major impairment, compared to 3% of controls. In their results they compare the numerical results, and the proportion of infants with impairments between those who are the most extremely preterm, 23-25 weeks, compared to 26-27 weeks. There are no differences between the subgroups.
As the authors rightly say, the rate of ‘neurobehavioral impairment… remains too high relative to controls’ it may be too high, but it is remarkable how well these babies are doing. Despite missing 17 to 13 weeks of intrauterine brain growth and development, the large majority are functioning well within the normal range. We still need to focus on why that period of being outside of the uterus affects brain development, though it would be very interesting to see in this cohort, what are the outcomes of those that did not get serious neonatal complications. If you take out the babies who had a late-onset infection, NEC or needed surgery, I guess you might end up with a group of babies nearly indistinguishable from the term controls.