Extremely Preterm Infants, long term outcomes

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.

About Keith Barrington

I am a neonatologist and clinical researcher at Sainte Justine University Health Center in Montréal
This entry was posted in Neonatal Research and tagged . Bookmark the permalink.

3 Responses to Extremely Preterm Infants, long term outcomes

  1. William Meadow says:

    hi Keith:

    you are very much a ‘glass half-full’ kind of guy;

    when you read the article, it doesn’t have nearly as positive a spin as you describe;

    now, I actually agree with you, but i’d be interested in Lex’ take on the data;

    how are you?

    love, to Annie and the kids


    • Hi Bill,
      I don’t think I mis-stated anything in their results, a glass which is half empty really is also half-full! And this glass looks a lot more like 4 fifths full. Now that means it is also 1 fifth empty and we need to do whatever we can to find out why, find out how to change that, and to get services for our graduates.
      If we forget the metaphor, yes the babies have definitely poorer development than the term controls, but they really aren’t that bad. About the same developmental progress as children who need major cardiac surgery in the neonatal period, for example.
      I wrote the post on the background of my concerns with the Canadian Pediatric Society over their atrocious new position statement about counseling mothers who might deliver extremely prematurely. I don’t think that results like the new ones presented in this article can be used to justify non-initiation of intensive care for the most immature babies, I am more and more thinking that the only really ethically relevant reason to not intervene in the delivery room is a very high risk of death, rather than the incredibly unpredictable risk of severe impairment, which this study shows is actually rather uncommon.

      And the kids and Annie are great. I had an awful trip to Atlanta yesterday, delayed flights, missed connection, but managed to blog a bit! Looking forward to the conference tomorrow
      Fond regards

  2. Namasivayam Ambalavanan MD says:

    On the one hand, I would agree with Bill. The authors were rather pessimistic. Even if the % of ex-preterm survivors with severe impairment is a small fraction, the WISC-IV differential of almost 10 points on most measures is rather worrisome. A 3 point differential is probably enough to influence college admissions and long-term earning. I am more concerned with a moderate reduction in cognitive performance in the majority of preterm infants (which may not reach the threshold for “impairment”) rather than a major reduction in a minority.
    On the other hand, I would also agree with you that these results should not be used to justify non-initiation of care. Our willingness to provide care for more immature infants is associated with better outcomes for more mature infants, without increasing mortality or the number of impaired survivors (e.g. PMID 22641761)
    This study also demonstrates the importance of having a “normal term cohort” for comparison. The incidence of learning difficulties is quite high (>10%) even in the controls.
    Best regards – keep up the good work on your blog.

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