Medical staff who treat very premature babies intensively have failed to raise survival rates, new figures revealed.
Researchers from Newcastle looked at data from the last 15 years and concluded that rates for those less than 24 weeks had not improved.
Previous studies suggested that infants born under 26 weeks experience better survival rates.
The team wanted to find out if babies had a better chance of living if they spent more time in intensive care or were resuscitated, compared to those who underwent less intrusive treatment in previous years.
Many parents wanted their baby resuscitating if it was born very premature, but this treatment did not improve chances of survival, they found.
The experts analysed infant deaths among 229 babies born alive at 22 or 23 weeks' gestation in Newcastle from 1993 to 2007.
These babies were born at a time-point that is considered to be the "margins of viability".
Of the babies, 210 died, of which one in three lived (34%) for more than six hours.
The length of time the babies lived gradually increased between 1993 and 2007, reflecting lengthier and more active treatment such as resuscitation and surgery.
But chances of survival did not improve over the same time-frame, the researchers said.
Six babies survived between 1993 and 1997, six survived between 1997 and 2002 and seven survived between 2003 and 2007.
Writing in the journal Archives of Disease in Childhood, the experts concluded: "An improved understanding of societal and parental attitudes and perceptions towards either the withholding or the withdrawing of active treatment at the margins of viability is needed."