Children born extremely prematurely are twice as likely to suffer serious problems as they grow up as had been thought, researchers reported yesterday.

Children born extremely prematurely are twice as likely to suffer serious problems as they grow up as had been thought, researchers reported yesterday.

The biggest long-term study of babies born at less than 26 weeks' gestation shows that almost half have a learning or other disability that interferes with their lives.

Babies born at this gestational age are intensely fragile and vulnerable with gelatinous skin, immature organs and under-developed lungs. The study, by researchers from Nottingham and London, is intended to help parents and doctors who face agonising decisions over how hard to struggle to keep the babies alive and when to withdraw care .

But the area is controversial with different policies among the premature baby units in the UK. Parents are relieved when there is no obvious physical disability. But problems with learning take longer to emerge yet can have an equally damaging effect on the child's chances of forging an independent life.

There were 1,289 babies born alive in the UK and Ireland below 26 weeks' gestation in 1995, of whom 308 survived, a death rate of 76 per cent.

The researchers followed the survivors from birth and assessed them at two and a half and six and a half years of age. The two and a half year assessment, published four years ago, showed one in four of the babies had a severe disability but half were unaffected.

The finding at age six and a half, shows 22 per cent of the children had a severe disability such as inability to walk caused by cerebral palsy, very low cognitive ability, blindness or deafness. A further 24 per cent were moderately disabled with cerebral palsy, had IQ scores in the special needs range and lesser problems with hearing and vision. In the normal population, these problems occur in less than 1 per cent of babies born at term. Only 20 per cent of the very premature babies had no problems.

Neil Marlow, professor of neonatal medicine at Nottingham University who led the study, published in the New England Journal of Medicine, said: "One in five had no disability and one in three had a mild disability such as wearing glasses. So 54 per cent had a satisfactory outcome. But 46 per cent had a disability likely to cause them problems as they grow through childhood. This almost doubles the risk assessed at two and a half."

Boys were at more than twice the risk of girls with more than a third suffering severe or moderate disability compared with 13 per cent of girls.

However, it was important not to be too gloomy, Professor Marlow said. Specialists had pointed out that any children surviving and growing up after being born so early in pregnancy was a modern miracle. "Disability rates have grown as the children have got older but half are free of disability. This is a message parents are anxious to get across," he said.

There are 40,000 premature babies born each year in the UK and those born at less than 26 weeks are a very small proportion, Rob Williams, chief executive of Bliss, the premature baby charity, said.

In Holland, babies born at less than 25 weeks are not offered intensive care, under a national policy. But researchers rejected this option, saying the decision should be left to parents and doctors. Most premature baby units in Britain do not routinely offer resuscitation at 23 weeks, though some do.

Mr Williams said: "We hope this study will help understanding of what the implications are of going hell for leather to keep these babies alive."