Thirty years ago, no one would have expected babies born extremely prematurely—between 23 and 25 weeks’ gestation, considered the edge of viability—to survive long enough to worry about what the future might hold for them as third graders.
But times change. Treatments like surfactants and prenatal steroids, along with improvements in ventilators and nutrition, have often enabled children born in that “gray zone” to survive.
Thus, doctors and parents now can start to ask questions about the long-term development of extremely premature babies. How will he do—physically, cognitively, intellectually—in the long run? What impairments might she face, and how severe will they be?
Doctors typically answer those questions by carrying out a series of physical and cognitive assessments when the child is around 18 to 22 months old. But, as Mandy Brown Belfort, MD, MPH—a Boston Children’s Hospital neonatologist—notes, assessments at that age may make a child’s future chances look worse than they actually will be.
All about the timing
The issue is that doctors don’t really learn much at that 18- to 22-month old time frame that can tell them what a child’s future may hold.
“The language of a 2-year old is less well developed,” Belfort says. “They haven’t learned to read. They haven’t reached the kinds of academic achievement that you can measure in older children.
“Developmentally, at school age, children have a lot more abilities and do a lot more that we can measure that matter to their long term functioning,” she adds.
Which would suggest that assessing a child at a later age might be more effective, a view bolstered by a new analysis by a team from the Ottawa Hospital in Ontario. The team reviewed a group of studies documenting the outcomes of 4- to 8-year-old children who had been born in the “gray zone.”
As Belfort wrote in an accompanying editorial in JAMA Pediatrics, the Ottawa study found that about 24 percent of the 441 children included in the study who had been born at 25 weeks had some kind of moderate-to-severe impairment at school age. Put another way, “76 percent were either mildly impaired or unimpaired, an estimate that is more favorable than previously published 18- to 22-month outcomes.”
This finding means that children born at 25 weeks were less likely to have severe impairments like cerebral palsy, deafness or blindness at school age than was suggested in previous studies that only looked at toddlers.
According to the Ottawa study, children born even younger, at 23 or 24 weeks’ gestation, still don’t fare well: the rates of moderate-to-severe impairment at school age among these children were about 40 and 28 percent, respectively. But those numbers paint a much more hopeful picture when compared with assessments of toddlers, which find moderate-to-severe impairments in roughly 85 to 95 percent of children born at 23 weeks and 66 to 89 percent of those born at 24.
Different definitions of impairment
Belfort’s biggest concern with the study is that the authors grouped children with different impairments together into broad buckets.
“Someone who was profoundly deaf but was otherwise intact was counted in the same category as someone who had severe cognitive impairments and cerebral palsy and was blind,” Belfort explains. “Those are all considered ‘severely impaired outcomes,’” she continues, “but as a parent or patient or physician, they are very different” when it comes to day-to-day living and care.
But when asked whether the results of the Ottawa meta-analysis would cause her to change the advice she gives to the parents of extremely premature babies, even with its limitations, Belfort responded:
“The percentage of children with impairments at school age seems to be lower than the percentage who are considered impaired at 18- to 22- months. Some moderate-to-severe impairments may not persist into school age, and that’s important [for doctors and parents] to know.”