Babies who are born at 25 weeks' gestation or earlier and survive early life have a "substantial likelihood" of having a very low IQ or other neurodevelopmental problems in childhood, researchers said today.
In a review of nine past studies, they found between 24 and 43 percent of extremely premature infants went on to have moderate or severe impairment, depending on just how early the babies were born.
Dr. Henry Lee, from the Division of Neonatal & Developmental Medicine at Stanford University and Lucile Packard Children's Hospital in California, said it's a "very difficult circumstance for the family" when a baby is born between 22 and 25 weeks.
Normal gestation is 37 to 42 weeks. Twenty-two weeks is considered the earliest a baby can be born and still have a chance of surviving. But the odds can be so low, and the risks so high, that some hospitals might not even offer aggressive care to preemies delivered at 22 to 23 weeks, said Lee, who wasn't involved in the new research.
"First of all, they're at high risk of not even surviving, even when everything is done to help them," he told Reuters Health. "Even when they do survive, they have high rates of disability."
By 25 weeks in the womb, a baby's chances of surviving and going on to lead a normal life are thought to be significantly better.
Lee said the new data could be used to help counsel families of extremely premature infants.
"It's hopefully an informed decision that the family makes in terms of how they're going to proceed, whether to try to provide very aggressive, intensive care to these infants or potentially to provide palliative and comfort care," he said.
"The hard part too is there is still uncertainty. Even though there is this risk, there are some infants at each of these gestational ages that will survive and not have disability."
For their analysis, researchers led by Dr. Gregory Moore from The Ottawa Hospital in Ontario, Canada, pooled the results of nine studies that assessed kids born between 22 and 25 weeks' gestation when they were four to eight years old. Most of the studies were conducted in Europe and together they included close to 900 children.
Moderately or severely impaired children were those scoring in the lowest 2 to 3 percent on IQ tests, children with cerebral palsy and those who were fully or mostly deaf or blind.
Studies varied widely in the frequency of impairment they reported, likely based in part on different practices in different regions, the researchers said.
They found that across the board, children were at risk of neurodevelopmental problems - although those risks declined for every extra week in the womb.
Among babies born at 22 weeks, 43 percent were impaired. That compared to 40 percent of those born at 23 weeks, 28 percent born at 24 weeks and 24 percent born at 25 weeks' gestation, the study team reported Monday in JAMA Pediatrics.
About 4 to 5 percent of full-term babies go on to have some type of developmental problem, Moore said, but that includes children with milder impairment as well.
"Although substantial numbers of extremely preterm infants go on to develop moderate to severe (neurodevelopmental impairment), the results are not completely bleak in that over half of the children studied did not go on to develop moderate to severe impairment," Dr. Kimberly Noble, a pediatrician who studies child brain development at Columbia University in New York, said.
Noble, who wasn't involved in the new research, told Reuters Health in an email that it's unclear whether rates of impairment would be similar for U.S. babies born very early.
Moore, also from The Children's Hospital of Eastern Ontario, said the findings were limited by the small number of children born at the earliest gestations included in the studies.
"We don't want these (data) to make a physician automatically say, ‘There's no hope' or, ‘There's no chance,'" he told Reuters Health.
But, he added, "Many parents do think of long-term impairment as a major concern for them, and some parents think of it as a bigger concern than death, for example. For some parents knowing this data and knowing the limitations of it and speaking with a caring neonatologist about it, we would hope that that would help them in their decision making."