Babies born at or before 22 weeks should not be resuscitated or given intensive care, a report says.
The report says babies born at 22 weeks should not be resuscitated
The recommendation is being put forward by the Nuffield Council on Bioethics, which considers ethical questions raised by advances in medical research.
For those born after 23 weeks, the recommendation is that doctors should review the situation with the parents and take their wishes into account.
But doctors warned no two babies born at 22 or 23 weeks would be the same.
The report has been released after two years of research.
It also gives guidance on how parents should resolve arguments with doctors over the fate of their babies.
The report comes against a backdrop of medical advances which have been able to sustain the lives of very premature babies.
However, research shows that many of these babies do not live very long, or go on to develop severe disability.
Part of the problem is that despite advances in modern medicine, it is not always obvious to doctors which babies will survive and thrive.
Professor Margaret Brazier, who chaired the committee that produced the guidelines, said: "Natural instincts are to try to save all babies, even if the baby's chances of survival are low.
"However, we don't think it is always right to put a baby through the stress and pain of invasive treatment if the baby is unlikely to get any better and death is inevitable."
The inquiry also looked at longer-term support for families, and resource implications for the NHS.
But it rejected suggestions that active steps be taken to end life - so-called baby euthanasia - in certain circumstances.
Born before 22 weeks: No intensive care
22-23 weeks: No intensive care, unless parents request it after a thorough discussion of the risks and doctors agree
23-24 weeks: Parents, after a thorough discussion with the healthcare team, should have the final say
24-25 weeks: Give intensive care, unless the parents and the doctors agree there is no hope of survival, or the level of suffering is too high
Above 25 weeks: Intensive care as standard
Bliss, the premature baby charity, is campaigning for one-to-one neonatal intensive care, and for decisions to made based on clinical reasoning, and not financial constraints.
The charity said the UK had the highest rate of low birth weight babies in Western Europe.
About 300 babies are born in the UK each year at 23 weeks.
They have a 17% survival rate, compared with 50% for those born at 25 weeks.
Figures suggest that no baby survives at 21 weeks, while only 1% survive to leave hospital at 22 weeks.
Andy Cole, Bliss chief executive, said: "While only a small percentage of infants in the UK are born at 24 weeks or less, it is essential that every baby should be treated as an individual and given the best and most appropriate care at the point of life.
"We strongly endorse the recommendation that assessment of care for the most vulnerable infants needs to be a joint decision between parents and clinicians."
All babies different
Dr Tony Calland, chairman of the medical ethics committee of the British Medical Association (BMA), said much of the report echoed "existing best practice".
But he added: "The BMA believes that blanket rules do not help individual parents or their very premature babies.
"Each case should be considered on its merits and its own context. While we believe that not all patients, including babies, benefit from medical intervention if survival is unlikely, it is important that each patient's circumstances are assessed independently.
"We therefore cannot agree with stringent cut-off points for treatment."
Bert Massie, chairman of the Disability Rights Commission, said: "The decision to treat or not treat should be based on individual assessment.
"To fail to do so would potentially be discriminatory and breach human rights legislation."
There are about 250 units in the UK offering neonatal intensive care, high dependency and special care.
Earlier this month the Royal College of Obstetricians and Gynaecologists said it wanted a discussion over whether "deliberate intervention" to cause death in severely disabled babies should be legalised.
But the report recommends the active ending of the life of newborn babies should not be allowed, no matter how serious their condition.
The Nuffield Council on Bioethics was established in 1991 to examine ethical questions raised by advances in biological and medical research.