Doctors are calling for a debate over proposals for the "mercy killing" of severely disabled babies.
Recent studies said the rate of preterm babies was increasing
The Royal College of Obstetricians and Gynaecologists wants a discussion over whether "deliberate intervention" to cause death should be legalised.
Withdrawing treatment is already permitted in some cases.
The college said it was not necessarily in favour of the move, but felt it should be debated. However, some are angry it has even been suggested.
Simone Aspis, of the British Council of Disabled People, said: "We really do not know how long babies and young people will live for.
"We should not deny people the opportunity to live for as long as they are able to."
And Matthew O'Gorman, a spokesman for the Life charity, said it was "extremely worrying".
"There is a huge difference between withdrawing invasive treatment that has become futile, and taking action to intentionally end a child's life because treatment is considered to be too expensive or time-consuming."
The college made its comments in a submission to the Nuffield Council on Bioethics, which is carrying out an inquiry into the viability of life.
Nuffield will publish its report on critical care decisions in foetal and neonatal medicine next week.
A working party has been consulting on the issue on the back of improvements in medical technology which means very premature and ill babies can survive, although some with severe disabilities.
The college said: "We would like the working party to think more radically about non-resuscitation, withdrawal of treatment decisions... and active euthanasia, as they are ways of widening the management options available to the sickest of newborns."
Maggie Blott, a member of the college, said these were "very difficult decisions" that would be taken over days, weeks and even months in consultation with the parents.
She added it was a debate that needed to happen.
Doctors have mixed views over the suggestions.
John Wyatt, professor of neonatal paediatrics at University College Hospital London, said: "It changes the nature of medicine... into some kind of social engineering."
But John Harris, professor of bioethics at the University of Manchester, said it was not a question of whether or not these decisions were taken - as they already were through withdrawing treatment - but how to take them in the most humane way.