You had a lot of work to do when you were in the womb, what with the business of growing from a single cell to a squalling, eight-pound human in just nine months. That’s why you needed every one of the 40 weeks of gestation you got, and why premature babies—especially extremely premature ones, born at just 23 or 24 weeks—start life at such a disadvantage.
Now, however, there’s some very good news on the preemie front. According to a study published in the ), most premature babies, including the ones at the extremes, are ready to begin kindergarten on time and perform as well as full-termers in primary and middle school. Some even score high enough on standardized tests to be considered gifted.
In general, the outlook for premature babies has improved steadily since the 1960s, with the minimum age of viability falling by at least one gestational week per decade. That means that while the survival of a preemie born at 32 weeks was once a very uncertain thing, 95% or more of those babies now make it home from the hospital healthy and well. For kids born at 25 weeks, the odds are still 76%, but they fall after that to 56% at 24 weeks, 26% at 23 weeks and just 5% at 22 weeks.
Babies who do survive may face multiple physical and developmental challenges—and cognitive ability has always been one of the hardest to parse. To help clarify things, Dr. Craig Garfield, associate professor of pediatrics and medical social sciences at Northwestern University, along with his colleagues, assembled an impressively large sample group, looking at all babies born in the state of Florida from 1992 to 2002. Florida represents an especially good laboratory to track student performance because of the state’s widely lauded tests of all pre-schoolers for kindergarten readiness and for the annual Florida Comprehensive Achievement Test (FCAT) administered to students in grades three through eight.
Of the 1.3 million baby Floridians born in the target decade whose records were complete enough to be included in the study, only 925 came into the world at the extremely premature 23 to 24 week mark. That’s a very small population compared to the overall group, but still more than large enough for statistical significance.
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When Garfield’s group crunched the gestational age and academic numbers, they got encouraging results. Of babies born in the 23 to 24 week window, 65% were considered kindergarten-ready on time, which is not terribly far off the 85% rate for full-term babies. The 23-weekers did perform worse than full-termers on the FCAT, finishing two-thirds of a standard deviation behind the rest of the population their age. On the 0 to 800 scale of the more familiar SAT, that would mean a 66-point deficit—a definite disadvantage, but hardly a fatal one. And just as survival rates can jump dramatically with even a little more time in the womb, so can cognitive performance: kids born at 29 to 30 weeks would be only 18 points behind on the 800 scale, and those born at 35 to 36 weeks would lose a negligible three points.
Discouragingly, 33.5% of extremely premature kids were ranked as low academic performers by Florida’s scoring standards, compared to just 5.8% of full term babies. Still, that means that about two-thirds of the extreme preemie group is well within the normal range—a better outcome than most parents expect. Not only do most of the littlest babies perform up to grade-level in school, but some excel brilliantly, with 1.8% earning the gifted honorific. That’s lower than the 9.5% of 40-weekers, but the fact that kids with little more than half as much time in the womb are in the game at all is a happy surprise.
None of this means that extreme preemies aren’t at a disadvantage from the beginning of life. But it does mean that their parents, doctors and teachers are learning to play that bad hand better and better all the time. That, in turn, means a better chance for a completely full life.
Jeffrey Kluger at jeffrey.kluger.