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% of extremely premature infants went on to have moderate or
severe impairment, depending on just how early the babies were born.
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 at
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.
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.
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
Pooled results for analysis
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 at 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% 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.
babies born at 22 weeks, 43% were impaired. That compared to 40% of those born
at 23 weeks, 28% born at 24 weeks and 24% born at 25 weeks' gestation, the
study team reported Monday in JAMA Pediatrics. About 4% to 5% of full-term
babies go on to have some type of developmental problem, Moore said, but that
includes children with milder impairment as well.
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 paediatrician who studies child
brain development at Columbia University in New York, said.
Analysing the study
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 US babies born very
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.
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."