I'm hopeful we can improve outcomes for this particularly risky group

Professor Neil Marlow, University of Nottingham

Only 308 survived. Of these, 155 had no problems. However, some problems caused by prematurity, including hyperactivity and learning difficulties, may not show up until the child is five years old.

The remaining 153 infants had developed a wide range of disabilities by the time they were two and a half years old.

Boys were more likely to have problems than girls but the chance of disability was not greater for those born at 22 weeks than for those born three weeks later.

More than half of these infants were slow to learn to speak. Others were slow developing any communication, a few could only communicate by sign and some could not communicate at all.

Improvements

Professor Neil Marlow, who led the research, said the study was the first to really let parents know what chances of life a baby born before 26 weeks has.

He said care for very premature babies was improving all the time.

"I hope that this group of babies, the most vulnerable group, will benefit as full-term babies have done over the past few years.

"I know the care is improving all the time and I'm hopeful we can improve outcomes for this particularly risky group.

"The level of care is always improving and the technology of medicine too. We would have expected to see similar figures for babies born full-term 10 to 15 years ago," he said.

The study is published in the latest issue of the New England Journal of Medicine.

Further study

Action Research, a medical research charity, said it was important that the causes of premature labour are also studied.

It is currently funding two projects. These include work on developing drugs to enable women to carry their babies to full term and another study which is trying to identify what triggers the onset of labour.

Its director general Anne Luther said tackling premature labour could ensure babies get the best start in life.

"Nowadays, much can be done to help these babies but about 7,000 of them are likely to need prolonged help in intensive care.

"Understanding what triggers off the process of labour and preventing it from happening prematurely will help to ensure that every baby gets off to the best possible start in life."